ArticlePDF AvailableLiterature Review


Preterm infants in the neonatal intensive care unit (NICU) often close their eyes in response to bright lights, but they cannot close their ears in response to loud sounds. The sudden transition from the womb to the overly noisy world of the NICU increases the vulnerability of these high-risk newborns. There is a growing concern that the excess noise typically experienced by NICU infants disrupts their growth and development, putting them at risk for hearing, language, and cognitive disabilities. Preterm neonates are especially sensitive to noise because their auditory system is at a critical period of neurodevelopment, and they are no longer shielded by maternal tissue. This paper discusses the developmental milestones of the auditory system and suggests ways to enhance the quality control and type of sounds delivered to NICU infants. We argue that positive auditory experience is essential for early brain maturation and may be a contributing factor for healthy neurodevelopment. Further research is needed to optimize the hospital environment for preterm newborns and to increase their potential to develop into healthy children.
Ann. N.Y. Acad. Sci. ISSN 0077-8923
Issue: The Neurosciences and Music IV: Learning and Memory
Auditory brain development in premature infants:
the importance of early experience
Erin McMahon,1Pia Wintermark,2and Amir Lahav1,3
1Department of Newborn Medicine, Brigham and Women’s Hospital, Boston, Massachusetts. 2Division of Newborn Medicine,
Montreal Children’s Hospital, McGill University, Montreal, Quebec, Canada. 3Department of Pediatrics, MassGeneral Hospital
for Children, Harvard Medical School, Boston, Massachusetts
Address for correspondence: Amir Lahav, ScD, PhD, The Neonatal Research Lab, Department of Newborn Medicine, 75
Francis Street, Boston, Massachusetts 02115.
Preterm infants in the neonatal intensive care unit (NICU) often close their eyes in response to bright lights, but they
cannot close their ears in response to loud sounds. The sudden transition from the womb to the overly noisy world
of the NICU increases the vulnerability of these high-risk newborns. There is a growing concern that the excess noise
typically experienced by NICU infants disrupts their growth and development, putting them at risk for hearing,
language, and cognitive disabilities. Preterm neonates are especially sensitive to noise because their auditory system
is at a critical period of neurodevelopment, and they are no longer shielded by maternal tissue. This paper discusses
the developmental milestones of the auditory system and suggests ways to enhance the quality control and type of
sounds delivered to NICU infants. We argue that positive auditory experience is essential for early brain maturation
and may be a contributing factor for healthy neurodevelopment. Further research is needed to optimize the hospital
environment for preterm newborns and to increase their potential to develop into healthy children.
Keywords: auditory; brain; prematurity; newborns; noise; plasticity
Prematurity is the leading cause of death in the first
month of life and a major cause of long-term disabil-
ity.1Advances in neonatal care have increased the
survival rate of ailing premature newborn infants.2
However, despite these advances, premature infants
are still prone to developmental problems that may
persist throughout their lifetime.3–5 These include
deficits in hearing, attention, memory, speech, lan-
guage, social behavior, and self-regulation.6–8 Be-
cause these problems are too often seen in neonatal
intensive care unit (NICU) graduates, it is possible
that the origin of these problems may be attributed
to environmental factors, such as the acoustic envi-
ronment in the NICU. This article is not an exhaus-
tive review, but is intended to highlight the concept
that preterm newborns are at a critical period for au-
ditory development and therefore must be provided
with appropriate auditory input and careful protec-
tion against overstimulation during their prolonged
stay in the NICU. The current design of most NICUs
Auditory developmental milestones
To better understand the need for auditory pro-
tection and the importance of early auditory ex-
perience, it is necessary to point out some of the
most important developmental milestones of audi-
tory development in the fetal and neonatal periods.
The development of the auditory system is an elab-
orate process that begins very early in gestation.9All
major structures of the ear, including the cochlea,
are in place between 23 and 25 weeks gestational
age (GA).9–11 Thus, unless a congenital abnormality
is present, most preterm infants can already hear
when first admitted to the NICU. The human fe-
tus can perceive and react to auditory information
starting at approximately week 26 of life.12 Begin-
ning between 26 and 30 weeks GA, hair cells in
the cochlea are fine tuned for specific frequencies
and can translate vibratory acoustic stimuli into an
doi: 10.1111/j.1749-6632.2012.06445.x
Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences. 17
Auditory development in preterm infants McMahon et al.
electrical signal that is sent to the brainstem.13 Be-
yond 30 weeks GA, the auditory system is mature
enough to permit complex sounds and distinguish
between different speech phonemes,10,14,15 which is
presumably the beginning of language and speech
development.16 Finally, by 35 weeks GA, auditory
processing facilitates learning and memory forma-
tion.17,18 Therefore, there is a need early on to pro-
tect preterm newborns from auditory stimuli they
are not yet ready to handle.19
Many of the sounds that are audible in the womb
are generated internally by the mother’s respira-
tion, digestion, heart rhythm, and physical move-
ments.20–22 Fetuses, however, can also respond to
sounds originated outside of the womb, such as
music and voice. These sounds stimulate the in-
ner ear through a mechanism of bone conduction.
The sound frequencies heard within the womb par-
allel the course of frequency development within
the cochlea,23 making the womb an optimal and
sheltered environment for auditory maturation. Be-
cause maternal tissue and fluid act as filters for high-
frequency sounds, the developing cochlear hair cells
are protected from potentially damaging noise.24 A
gradual exposure to low-frequency sounds first per-
mits the necessary fine tuning of the hair cells. As
the auditory system matures, it can process more
high-frequency patterns of human speech, such as
pitch, intonation, and intensity, which provide the
exogenous stimulation necessary to develop a neo-
cortical relationship with the cochlea.14 Being able
to hear these high-frequency sounds, in fact, wires
the fetus for language processing soon after it is
After birth, infants seem to prefer their mother’s
voice over an unknown female voice. This has been
demonstrated in several studies showing that new-
borns selectively respond to their mother’s speech
with detectable changes in heart rate25,26 and orient-
ing movements toward27 the source of the sound.
The fact that newborn infants show a clear prefer-
ence for their mother’s voice within only hours after
birth can be taken as evidence for the significance of
prenatal hearing experience,28 suggesting that audi-
tory attention, learning, and memory begin while
in the womb.
Auditory brain plasticity
Auditory brain plasticity is intimately linked with
early sensory experience. Functions of the cerebral
cortex and the sensory systems are mostly estab-
lished during a sensitive period in the neonatal
period when neural circuitry is first generated.29
This initial neural architecture leads to different
functional areas that systematically represent dif-
ferent environmental information, and appears to
constrain further plasticity later.30 Following this
critical period, the cerebral cortex and the audi-
tory system will only be refined and reorganized
during childhood and adulthood to optimize sen-
sory processing and adaptation to environmental
The development of the auditory cortex is heavily
dependent on the acoustic environment, as demon-
strated by both human and animal studies.30 For ex-
ample, rearing rat pups under various noise condi-
tions significantly affects the maturation time of au-
ditory cortical areas.32,33 Similarly, continuous ex-
posure to loud noise negatively affects the develop-
ment of auditory-related functions, including vocal
learning and spatial localization.34–37 These animal
studies demonstrate that changes in sensory input
can have profound effects on the functional organi-
zation of the developing cortex. Furthermore, they
implicate noise as a risk factor for abnormal sen-
sory development, and provide a basis for our con-
cerns regarding the adverse effects of NICU noise
on neonatal brain development in humans.
Deprivation of maternal sounds
Infants born prematurely spend their first weeks and
even months of life in the NICU. During this time,
they are deprived of the biological maternal sounds
they would otherwise be hearing in utero. These
sounds mainly include the low-frequency bands of
mother’s voice and the continuous, rhythmic stim-
ulation of the maternal heartbeat. Deprivation of
these sounds when the auditory system is at a crit-
ical period for development can have a profound
effect on auditory brain maturation and subsequent
speech and language acquisition.38–40
A deprived auditory cortex cannot mature nor-
mally.41 Evidence coming mainly from animal stud-
ies suggests that the functional development of the
auditory system is largely influenced by environ-
mental acoustic inputs in early life.42,43 For exam-
ple, depriving juvenile birds of normal auditory
experience delayed the emergence of topographic
brain circuitry.44 Similarly, prolonged auditory
deprivation has been shown to decrease the
18 Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences.
McMahon et al. Auditory development in preterm infants
expression levels of selective NMDA receptors in the
rat auditory cortex during early postnatal develop-
ment.45,46 In contrast, exposing infant rat pups to
an enriched auditory environment—either with47
or without48 music stimulation—has been shown
to enhance auditory discrimination and learning
abilities. In addition, infant rat pups raised under
sensory deafness conditions have been shown to
develop abnormal synaptic morphology in the pri-
mary auditory cortex in terms of dendrite shape,
length, and spine density.49 These studies demon-
strate a high inclination for auditory brain plasticity
in the neonatal period.
Taken together, these animal studies lend sup-
port to our concerns about the possibly harmful
auditory deprivation experienced by preterm in-
fants, even in the seemingly quiet and protected
environment of the incubator. It is, therefore, rea-
sonable to assume that the lack of sufficient oppor-
tunities to perceive maternal speech sounds during
NICU hospitalization can alter brain structure and
subsequently account for some of the hearing, lan-
guage, and attention deficits often seen in NICU
Effects of noise exposure
Unquestionably, the type of sounds and levels of
noise typically present in the NICU are very different
from those heard in the womb.9,50 Low-frequency
placental sounds in the amniotic environment are
replaced by unpredictable noise coming from venti-
lators, cardiac monitors, infusion pumps, pagers,
and alarms.24 This accumulation of background
noise,51–53 even within the seemingly protected in-
cubator,54–56 well exceeds the recommended levels
set by the American Academy of Pediatrics.57 Thus,
the current environment available to preterm in-
fants during their hospitalization is not optimal.24
NICU noise can result in detrimental health out-
comes.58–60 Loud noise can produce unwarranted
physiological changes in heart rate,61–63 blood pres-
sure,62 respiration, and oxygenation.64,65 Noise also
appears to cause hyperalertness, increased crying,
and reduced deep sleep.66 Our recent review pa-
per on this topic67 suggests that excessive exposure
to noise during the neonatal period can negatively
affect the cardiovascular and respiratory systems,
which can increase the risk for a variety of develop-
mental problems.
Clinical implications: what we can do
There are many things that can be done to improve
the auditory environment in the NICU. Our pri-
mary target should be the quality and quantity of
sounds surrounding NICU infants in order to guar-
antee optimal conditions for their growth and de-
velopment. The two main problems that should be
addressed are the high levels of noise in the NICU
and the lack of meaningful acoustic input during a
critical time for auditory brain development. Here,
we propose a number of evidence-based suggestions
that can be implemented into routine NICU care to
potentially improve health outcomes of infants born
How to address the problem
of environmental noise?
Improve NICU design
The concept of individual rooms for NICU patients
is still evolving.68 However, there seems to be a
consensus among both parents69 and care givers70
that the private-room NICU design is highly pre-
ferred. A recent model suggests that the transition
from an open-bay NICU to a private-room NICU
can potentially improve developmental outcomes
through mediating factors such as developmental
care, family-centered care, parental stress, staff be-
havior, and medical practices.71,72
Modify equipment
The default volume settings on many of the NICU’s
alarm systems are often unnecessarily high. Alarm
volumes should be reduced, especially at night. Re-
ducing the volume of pagers, alarms, telephones,
and intercoms should improve overall noise pollu-
tion.73 In addition, noise-making equipment, such
as metal trashcans, should be replaced with qui-
eter alternatives. Motorized paper towel dispensers
should be cautiously avoided in spite of their poten-
tial to reduce infection rates.74
Consider a silent alarm system
Substituting audible ringtones of telephones and
pagers with a silent vibration should also be con-
sidered. In this case, monitors will text events to
all the nurses in the NICU pod through a wireless
device rather than alarming at the infant’s bedside.
Previous studies taking this approach have reported
positive results.75
Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences. 19
Auditory development in preterm infants McMahon et al.
Change staff behavior
It is important to educate NICU staff, including
physicians, nurses, respiratory therapists, and par-
ents, about the negative impact of noise on devel-
opmental outcomes. Increasing staff awareness can
lead to significant changes in attitude and behavior,
such as redirecting loud conversations away from
patient areas and gently closing incubator doors.
Research has shown that staff behavior alone can
have an impact on the overall noise levels in the
NICU, making it a more positive environment for
growth and development.72,76
Routinely measure noise levels
Considering the evidence regarding the negative ef-
fects of noise on neonates, it is somewhat surpris-
ing that noise levels are not routinely measured in
most NICUs. Noise level meters should be placed at
the bedside to maintain quiet and ensure compli-
ance with the recommendations set by the Amer-
ican Academy of Pediatrics.57 Periodic monitoring
of noise levels is necessary to identify new sources
efficacy of noise-reduction strategies.75
Avoid earmuffs
filter noxious sounds, evidence for their effective
use in NICU infants has been rather limited.77 The
use of ear protection in the NICU may carry risks
that outweigh the benefits. The constant contact
with earmuffs may present tactile overstimulation
that the infant’s sensory system is too immature to
process.78 In addition, earmuffs actually increase the
risk for auditory deprivation by blocking the already
limited human speech sounds that are available to
the infant.
How to address the problem of auditory
Provide kangaroo care
Kangaroo care is a common evidence-based method
for “maternalizing” the NICU experience for
preterm infants soon after birth.79–81 During kan-
garoo care, the infant is placed in a supine position
on the mother’s (or father’s) chest to have direct
skin-to-skin contact.82 The infant can then presum-
ably hear and feel the low-frequency sounds of the
maternal voice heartbeat through the skin. Kan-
garoo care has been associated with a decreased
risk of mortality83 and has been shown to pro-
mote maternal–infant bonding.84,85 However, from
an auditory perspective, kangaroo care also pro-
vides the infant with important opportunities to
process meaningful maternal sounds that would
otherwise not be available, especially in the case of
low birth-weight infants who experience prolonged
Play the mother’s voice inside the
Although kangaroo care is strongly encouraged, in
reality, there are times when the mother cannot be
present in the NICU or the infant is too sick to be
held outside the incubator. During those times, ex-
posing the infant to audio recordings of the mother’s
voice will benefit both the mother and the baby: it al-
lows the mother to be with her infant virtually, even
when she is not there physically, and can provide the
infant with a wide range of maternal vocalizations,
including singing lullabies, reading books, and im-
provisational speaking. This should supply the ap-
propriate language stimulation that is believed to
promote hearing, speech, and social development.
Studies have shown that preterm infants who were
exposed to an audio recording of their mother’s
voice achieved full enteral feed quicker86 and showed
meaningful changes in heart rate87 compared to
age-matched controls receiving routine care (for re-
view, see Ref. 88). While this approach has great
potential, further research is needed to determine
its optimal dose and long-term effects on child
Introduce vocal music
Exposing preterm infants to vocal music, such as
lullabies, has been shown to increase oxygen satura-
tions, improve weight gain, and nonnutritive suck-
ing, and shorten overall hospital stay.89–95 Voc a l mu -
sic is comprised of a large spectrum of intonations
and vocalizations, both rhythmic and melodic,96
which can provide adequate exposure to language
stimuli when the live mother’s voice is not avail-
able.97 Vocal music, in particular, may also be bi-
ologically meaningful when sung by the mother.
Combining live singing with kangaroo care may thus
offer a perfectly viable way to warmly immerse the
infant with soothing maternal sounds.98,99 Any at-
tempt to play other forms of music, such as purely
instrumental pieces, must be taken with caution as
this type of auditory stimulation cannot properly
address the problem of maternal sound deprivation.
20 Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences.
McMahon et al. Auditory development in preterm infants
According to a recent review by Neal and Lindeke,100
there is still controversy about the use of music as
a developmental care strategy in the NICU, espe-
cially in infants <32 weeks GA. More controlled
and rigorous studies are needed to definitively test
the long-term effects of this therapeutic approach.
Be sensitive to the infant’s state
When providing auditory stimulation in the NICU,
whether it is vocal music or the mother’s voice, it is
critically important to pay attention to the infant’s
behavioral cues and modulate the stimulation ac-
cordingly. Preterm infants have limited capacity to
defend themselves against sensory stimulation that
is age-inappropriate with respect to duration, com-
plexity, and intensity.101 Infants will exhibit stress
signals in autonomic, motor, and self-regulatory
systems in response to irritating stimulation.102 In
accordance with the developmental care guidelines
proposed by Heidi Als,19,103 we recommend that
both parents and caregivers should develop the nec-
essary skills required to understand and respond
to the infant’s behavioral cues, and any automated
systems that provide infants with auditory stimula-
tion at a potentially inappropriate time should be
Carefully select audio equipment
Commercially available audio equipment, such as
speakers, digital players, and cables, must be care-
fully tested for safety before it is used inside an in-
cubator or a crib as these products are not typi-
cally designed for NICU use. Testing must ensure
that the audio equipment delivers sound at a safe
decibel level for preterm newborns, does not cre-
ate electrical interference with medical equipment
such as cardiac monitors and ventilators, is resistant
against high temperature (36C) and humidity
(75%) levels typically present inside the incuba-
tor, and can be routinely cleaned with disinfectant
to ensure compliance with infection control regula-
tions. For a full description of recommended tests
and audio equipment, see Ref. 104.
The primary auditory stimulation infants receive in
the NICU is ambient noise. Thus, the prolonged
hospitalization experienced by preterm infants may
compromise development. This should no longer be
ignored or devalued. Emphasis must be placed on
making the NICU a more conducive environment
for positive auditory experience. This early auditory
experience occurs at the most critical period for
neural wiring and subsequent neurodevelopment.
Efforts should be made to envelop the preterm in-
fants with more womb-like sounds to compensate
for the loss of exposure to the maternal voice and
heartbeat and to protect them from potentially ad-
verse noise effects.
This work was supported by the following founda-
tions: Christopher Joseph Concha, Hailey’s Hope,
Capita, Waterloo, Heather on Earth, Christopher
Douglas Hidden Angel, and Peter and Elizabeth C.
Tower, as well as by the John Alden Trust, Lifespan
Healthcare, and Philips Healthcare.
Conflicts of interest
The authors declare no conflicts of interest.
1. Elder, D.E., A. Wong & J.M. Zuccollo. 2009. Risk factors for
and timing of death of extremely preterm infants. Aust. N Z
J. Obstet. Gynaecol.49: 407–410.
2. Wilson-Costello, D. 2007. Is there evidence that long-term
outcomes have improved with intensive care? Semin. Fetal
Neonatal Med.12: 344–354.
3. Msall, M.E. & J.J. Park. 2008. The spectrum of behavioral
outcomes after extreme prematurity: regulatory, attention,
social, and adaptive dimensions. Semin. Perinatol.32: 42–
4. Marlow, N., L. Roberts & R. Cooke. 1993. Outcome at 8
years for children with birth weights of 1250 g or less. Arch.
Dis. Child.68: 286–290.
5. Marlow, N. et al. 2005. Neurologic and developmental dis-
ability at six years of age after extremely preterm birth. N.
Engl. J. Med.352: 9–19.
6. Huang, L., K. Kaga & K. Hashimoto.2002. Progressive hear-
ing loss in an infant in a neonatal intensive care unit as
revealed by auditory evoked brainstem responses. Auris .
Nasus. Larynx .29: 187–190.
7. McCormick, M.C., K. Workman-Daniels & J. Brooks-
Gunn. 1996. The behavioral and emotional well-being of
school-age children with different birth weights. Pediatrics
97: 18–25.
8. Xoinis, K. et al. 2007. Extremely low birth weight infants
are at high risk for auditory neuropathy. J. Perinatol.27:
9. Hall, J.W., 3rd. 2000. Development of the ear and hearing.
J. Perinatol.20: S812–S820.
10. Cheour-Luhtanen, M. et al. 1996. The ontogenetically earli-
est discriminative response of the human brain. Psychophys-
iology 33: 478–481.
11. Eldredge, L. & A. Salamy. 1996. Functional auditory devel-
opment in preterm and full term infants. EarlyHum.Dev.
45: 215–228.
Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences. 21
Auditory development in preterm infants McMahon et al.
12. Ruben, R.J. 1992. The ontogeny of human hearing. Acta
Otolaryngol.112: 192–196.
13. Querleu, D. et al. 1989. Hearing by the human fetus? Semin.
Peri natol .13: 409–420.
14. Hepper, P., D. Scott & S. Shahidullah. 1993. Newborn and
fetal response to maternal voice. J. Reprod. Infant Psychol.
11: 147–153.
15. Johansson, B., E. Wedenberg & B. Westin. 1964. Measure-
ment of tone response by the human foetus. A preliminary
report. Acta Otolaryngol.57: 188–192.
16. Mehler, J. et al. 1988. A precursor of language acquisition
in young infants. Cognition 29: 143–178.
17. Birnholz, J.C. & B.R. Benacerraf. 1983. The development of
human fetal hearing. Science 222: 516–518.
18. Moon, C.M. & W.P. Fifer. 2000. Evidence of transnatal au-
ditory learning. J. Perinatol.20: S37–S44.
19. Als, H. et al. 2005. The assessment of preterm infants’ be-
havior (APIB): furthering the understanding and measure-
ment of neurodevelopmental competence in preterm and
full-term infants. Ment. Retard. Dev. Disabil. Res. Rev.11:
20. Gerhardt, K.J., R.M. Abrams & C.C. Oliver. 1990. Sound
environment of the fetal sheep. Am. J. Obstet. Gynecol .162:
21. Querleu, D. et al. 1988. Fetal hearing. Eur. J. Obste t. Gynecol.
Reprod. Biol.28: 191–212.
22. Armitage, S.E., B. A. Baldwin & M.A. Vince. 1980. The fetal
sound environment of sheep. Science 208: 1173–1174.
23. Fifer, W.P., Moon, C. 1988. Auditory Experience in the Fe-
tus. In Behavior of the Fetus. W.P. Smotherman, S.R. Robin-
son, Eds: 175–188. Telford Press. Caldwell, NJ.
24. Graven, S.N. 2000. Sound and the developing infant in the
NICU: conclusions and recommendations for care. J. Peri-
natol.20: S88–S93.
25. Ockleford, E.M. et al. 1988. Responses of neonates to par-
ents’andothers’voices.Early Hum. Dev.18: 27–36.
26. Kisilevsky, B.S. et al. 2009. Fetal sensitivity to properties of
maternal speech and language. Infant B ehav. Dev.32: 59–71.
27. Querleu, D. et al. 1984. Reaction of the newborn infant less
than 2 hours after birth to the maternal voice. J. Gynecol.
Obstet.Biol.Reprod.(Paris)13: 125–134.
28. DeCasper, A.J. & W.P. Fifer. 1980. Of human bonding:
newborns prefer their mothers’ voices. Science 208: 1174–
29. Sanes, D.H. & S. Bao. 2009. Tuning up the developing au-
ditory CNS. Curr. Opin. Neurobiol.19: 188–199.
30. Dahmen, J.C. & A.J. King. 2007. Learning to hear: plasticity
of auditory cortical processing. Curr. Opin. Neurobiol.17:
31. Yan, J. 2003. Canadian Association of Neuroscience Review:
development and plasticity of the auditory cortex. Can. J.
Neurol. Sc i.30: 189–200.
32. de Villers-Sidani, E. et al. 2008. Manipulating critical pe-
riod closure across different sectors of the primary auditory
cortex. Nat. Neurosci.11: 957–965.
33. Chang, E.F. & M.M. Merzenich. 2003. Environmental noise
retards auditory cortical development. Science 300: 498–
34. Philbin, M. K., D.D. Ballweg & L. Gray. 1994. The effect of an
intensive care unit sound environment on the development
of habituation in healthy avian neonates. Dev. Psychobiol.
27: 11–21.
35. Marler, P. et al. 1973. Effects of continuous noise on avian
hearing and vocal development. Proc. Natl. Acad. Sci. USA
70: 1393–1396.
36. Chin, B.B. et al. 2002. Standardized uptake values in 2-
deoxy-2-[18F]fluoro-D-glucose with positron emission to-
mography. Clinical significance of iterative reconstruction
and segmented attenuation compared with conventionalfil-
tered back projection and measured attenuation correction.
Mol. Imaging. Biol.4: 294–300.
37. Withington-Wray, D.J. et al. 1990. The maturation of the
superior collicular map of auditory space in the guinea pig
is disrupted by developmental auditory deprivation. Eur. J.
Neurosci.2: 693–703.
38. Fifer, W.P. & C.M. Moon. 1994. The role of mother’s voice
in the organization of brain function in the newborn. Acta
Paediatr. Suppl.397: 86–93.
39. Shahidullah, S. & P.G. Hepper. 1994. Frequency discrimi-
nation by the fetus. Early Hum Dev.36: 13–26.
40. deRegnier, R.A. et al. 2002. Influences of postconceptional
age and postnatal experience on the development of au-
ditory recognition memory in the newborn infant. Dev.
Psychobiol.41: 216–225.
41. Neville, H. & D. Bavelier. 2002. Human brain plasticity:
evidence from sensory deprivation and altered language
experience. Prog. Brain. Res.138: 177–188.
42. Klinke, R. et al. 2001. Plastic changes in the auditory cortex
of congenitally deaf cats following cochlear implantation.
Audiol. Neurootol.6: 203–206.
43. Kral, A. et al. 2002. Hearing after congenital deafness: central
auditory plasticity and sensory deprivation. Cereb. Cortex
12: 797–807.
44. Iyengar, S. & S.W. Bottjer. 2002. The role of auditory expe-
rience in the formation of neural circuits underlying vocal
learning in zebra finches. J. Neurosci.22: 946–958.
45. Lu, al . 2008. Early auditory deprivation alters expression
of NMDA receptor subunit NR1 mRNA in the rat auditory
cortex. J. Neurosci. Res.86: 1290–1296.
46. Bi, C. et al. 2006. The effect of early auditory deprivation
on the age-dependent expression pattern of NR2B mRNA
in rat auditory cortex. Brain Res.1110: 30–38.
47. Xu, J. et al. 2009. Early auditory enrichment with music
enhances auditory discrimination learning and alters NR2B
protein expression in rat auditory cortex. Behav. Brain Res.
196: 49–54.
48. Cai, R. et al. 2009. Environmental enrichment improves be-
havioral performance and auditory spatial representation of
primary auditory cortical neurons in rat. Neurob iol . Learn.
Mem.91: 366–376.
49. Bose, M. et al. 2010. Effect of the environment on the den-
dritic morphology of the rat auditory cortex. Synapse 64:
50. Abrams, R. M. & K.J. Gerhardt. 2000. The acoustic environ-
ment and physiological responses of the fetus. J. Perinatol.
20: S31—S36.
51. Darcy, A.E., L.E. Hancock & E.J. Ware. 2008. A descriptive
study of noise in the neonatal intensive care unit: ambient
levels and perceptions of contributing factors. Adv. Neonatal
Care 8: S16–S26.
22 Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences.
McMahon et al. Auditory development in preterm infants
52. Williams, A. L., W. van Drongelen & R.E. Lasky. 2007. Noise
in contemporary neonatal intensive care. J. Acoust. Soc. Am.
121: 2681–2690.
53. Lasky, R.E. & A.L. Williams. 2009. Noiseand lig ht exposures
for extremely low birth weight newborns during their stay
in the neonatal intensive care unit. Pediatrics 123: 540–546.
54. Antonucci, R., A. Porcella & V. Fanos. 2009. The infant
incubator in the neonatal intensive care unit: unresolved
issues and future developments. J. Perinat. Med.37: 587–
55. Kirchner, L. et al. 2011. In vitro comparison of noise levels
produced by different CPAP generators. Neonatology 101:
56. Altuncu, E. et al. 2009. Noise levels in neonatal intensive
care unit and use of sound absorbing panel in the isolette.
Int. J. Pediatr. Otorhinolaryngol.73: 951–953.
57. Committee on Environmental Health. 1997. Noise: a haz-
ard for the fetus and newborn—American Academy of Pe-
diatrics. Pediatrics 100: 724–727.
58. Brown, G. 2009. NICU noise and the preterm infant. Neona-
tal Netw.28: 165–173.
59. Bremmer, P., J.F. Byers & E. Kiehl. 2003. Noise and the
premature infant: physiological effects and practice impli-
cations. J. Obstet. Gynecol. Neonatal Nurs.32: 447–454.
60. Blackburn, S. 1998. Environmental impact of the NICU on
developmental outcomes. J. Pediatr. Nurs.13: 279–289.
61. Field, T. et al. 1979. Cardiac and behavioral responses to
repeated tactile and auditory stimulation by preterm and
term neonates. Develop. Psychol.15: 406–416.
62. Vranekovic, G. et al. 1974. Heart rate variability and cardiac
response to an auditory stimulus. Biol. Neonate 24: 66–73.
63. Zahr, L.K. & S. Balian. 1995. Responses of premature infants
to routine nursing interventions and noise in the NICU.
Nurs. Re s.44: 179–85.
64. Johnson, A.N. 2001. Neonatal response to control of noise
inside the incubator. Pediatr. Nurs. 27: 600–605.
65. Wharrad, H.J. & A.C. Davis. 1997. Behavioural and auto-
nomic responses to sound in pre-term and full-term babies.
Br.J.Audiol.31: 315–329.
66. Strauch, C., S. Brandt & J. Edwards-Beckett. 1993. Imple-
mentation of a quiet hour: effect on noise levels and infant
sleep states. Neona tal . Netw.12: 31–35.
67. Wachman, E.M. & A. Lahav. 2010. The effects of noise on
preterm infants in the NICU. Arch.Dis.ChildFetal.Neonatal
Ed 96: 305–309.
68. White, R.D. 2011. The newborn intensive care unit envi-
ronment of care: how we got here, where we’re headed, and
why. Semin. Perinatol. 35: 2–7.
69. Carter, B.S., A. Carter & S. Bennett. 2008. Families’ views
upon experiencing change in the neonatal intensive care
unit environment: from the ‘baby barn’ to the private room.
J. Perinatol.28: 827–829.
70. Stevens, D.C. et al. 2010. Neonatal intensive care nursery
staff perceive enhanced workplace quality with the single-
family room design. J. Perinatol.30: 352–358.
71. Lester, B.M. et al. 2011. Infant neurobehavioral develop-
ment. Semin. Perinatol.35: 8–19.
72. Philbin, M.K. & L. Gray. 2002. Changing levels of quiet in
an intensive care nursery. J. Perinatol.22: 455–460.
73. Philbin, M.K. 2004. Planning the acoustic environment of
a neonatal intensive care unit. Clin. Perinatol.31: 331–352,
74. Brandon, D.H., D.J. Ryan & A.H. Barnes. 2008. Effect of
environmental changes on noise in the NICU. AdvNeonatal.
Care 8: S5–S10.
75. Laudert, S. et al. 2007. Implementing potentially better
practices to support the neurodevelopment of infants in
the NICU. J. Perinatol.27(Suppl 2): S75–S93.
76. Milette, I. 2010. Decreasing noise level in our NICU: the im-
pact of a noise awareness educational program. Adv. Neona-
tal Care 10: 343–351.
77. Zahr, L.K. & J. de Traversay. 1995. Premature infant re-
sponses to noise reduction by earmuffs: effects on behav-
ioral and physiologic measures. J. Perinatol.15: 448–455.
78. Aita, M. & C. Goulet. 2003. Assessment of neonatal nurses’
behaviors that prevent overstimulation in preterm infants.
Intensive Crit. Care Nurs.19: 109–118.
79. Ferber, S.G. & I.R. Makhoul. 2004. The effect of skin-to-skin
contact (kangaroo care) shortly after birth on the neurobe-
havioral responses of the term newborn: a randomized,
controlled trial. Pediatrics 113: 858–865.
80. Charpak, N. et al. 2005. Kangaroo mother care: 25 years
after. Acta. Paediatr.94: 514–522.
81. Gale, G., L. Franck & C. Lund. 1993. Skin-to-skin (kanga-
roo) holding of the intubated premature infant. Neonatal
Netw .12: 49–57.
82. Anderson, G.C. 1991. Current knowledge about skin-to-
skin (kangaroo) care for preterm infants. J. Perinatol.11:
83. Conde-Agudelo, A., J.M. Belizan & J. Diaz-Rossello. 2011.
Kangaroo mother care to reduce morbidity and mortality
in low birthweight infants. Cochrane Database Syst. Rev.
84. Tessier, R. et al. 1998. Kangaroo mother care and the bond-
ing hypothesis. Pediatrics 102: e17.
85. Nyqvist, K.H. et al. 2011. Towards universal Kangaroo
mother care: recommendations and report from the First
European Conference and Seventh International Workshop
on Kangaroo Mother Care. Acta Paediatr.99: 820–826.
86. Krueger, C. et al. 2010. Maternal voice and short-term
outcomes in preterm infants. Dev. Psychobiol.52: 205–
87. Segall, M.E. 1972. Cardiac responsivity to auditory stimu-
lation in premature infants. Nurs. Res.21: 15–19.
88. Krueger, C. 2010. Exposure to maternal voice in preterm
infants: a review. Adv. Neonatal. Care 10: 13–18; quiz 19–
89. Cevasco, A.M. & R.E. Grant. 2005. Effects of the pacifier
activated lullaby on weight gain of premature infants. J.
Music Ther .42: 123–139.
90. Standley, J.M. et al. The effect of music reinforcement for
non-nutritive sucking on nipple feeding of premature in-
fants. Pediatr. Nurs. 36: 138–145.
91. Caine, J. 1991. The effects of music on the selected stress
behaviors, weight, caloric and formula intake, and length
of hospital stay of premature and low birth weight neonates
in a newborn intensive care unit. J. Music Ther.28: 180–
Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences. 23
Auditory development in preterm infants McMahon et al.
92. Chapman, J.S. 1975. The relation between auditory stimu-
lation of short gestation infants and their gross motor limb
activity. New York University. New York.
93. Coleman,J.M.,R.R.Pratt,R.A.Stoddard,D.R.Gerstmann,
& H. Abel. 1997. The effects of male and female singing and
speaking voices on selected physiological and behavioral
measures of premature infants in the intensive care unit.
Inter. J. Arts Medi. 5: 4–11.
94. Collins, S.K. & K. Kuck. 1991. Music therapy in the neonatal
intensive care unit. Neonatal Netw.9: 23–26.
95. Malloy, G. 1979. The relationship between maternal and
musical auditory stimulation and the developmental be-
havior of premature infants. Birth Defects: Original Article
Series 15: 81–98.
96. Trehub, S.E. 2001. Musical predispositions in infancy. Ann.
N.Y. Acad. Sci.930: 1–16.
97. Loewy, J.V. 1995. The musical stages of speech: a develop-
mental model of pre-verbal sound making. Music Ther. 13:
98. Lai, H.L. et al. 2006. Randomized controlled trial of music
during kangaroo care on maternal state anxiety and preterm
infants’ responses. Int. J. Nurs. Stud .43: 139–46.
99. Schlez, A. et al. 2011. Combining kangaroo care and live
harp music therapy in the neonatal intensive care unit set-
ting. Isr. Med. Assoc. J .13: 354–358.
100. Neal, D.O. & L.L. Lindeke. 2008. Music as a nursing inter-
vention for preterm infants in the NICU. Neonatal Netw.
27: 319–327.
101. Field, T. 1990. Alleviating stress in newborn
infants in the intensive care unit. Clin. Perinatol.17:
102. Symington, A. & J. Pinelli. 2003. Developmental care
for promoting development and preventing morbid-
ity in preterm infants. Cochrane Database Syst. Rev.
103. Als, H. et al. 1986. Individualized behavioral and environ-
mental care for the very low birth weight preterm infant at
high risk for bronchopulmonary dysplasia: neonatal inten-
sive care unit and developmental outcome. Pediatrics 78:
104. Panagiotidis, J. & A. Lahav. 2010. Simulation of prenatal
maternal sounds in NICU incubators: a pilot safety and
feasibility study. J. Matern Fetal Neonatal Med 23(Suppl 3):
24 Ann. N.Y. Acad. Sci. 1252 (2012) 17–24 c
2012 New York Academy of Sciences.
... morphofunctional development of all sensory systems of a premature baby, and the auditory system is no exception. This is due, firstly, to the immaturity of the hearing organ at birth, early exposure to the extrauterine environment, as well as the high vulnerability of immature auditory structures to damaging factors [8][9][10][11]. Apart from prematurity itself, a number of other factors have been associated with neurodevelopmental impairment including peripheral hearing loss and auditory processing disorders (APDs) in preterm children. These include perinatal and neonatal hypoxia-ischemia, extended stays in the neonatal intensive care unit (NICU), neonatal hyperbilirubinemia requiring exchange transfusion, a longer period of assisted ventilation and prolonged respiratory support, acquired hypoxicischemic encephalopathy, and others [12][13][14][15][16].The coexistence of many perinatal adverse factors can negatively affect the development of the auditory system of a premature baby with the formation of insufficiency at any level. ...
... Thus, any damaging factor affecting the developing sensory system in a certain period of time can further contribute to disorders of auditory processing in premature children and lead to delays or disorders in the CANS maturation process [8,29]. These abnormalities can persist for a long time and, even in the absence of peripheral auditory impairment, lead to central auditory processing deficits that may affect different levels of the auditory system and be present at different ages. ...
... In the 6-7-year-old subgroup, only one child with SNHL and one child with ANSD successfully completed RGDT; in the subgroup of 8-9 year-olds, only five children with ANSD and two children with SNHL successfully performed the test. One child with SNHL from the subgroup of 6-7 year-olds and two children (one with SNHL and one with ANSD) from the subgroup of [8][9] year-olds demonstrated normal gap detection thresholds (two of them had mild hearing loss and one had a moderate degree of hearing loss). ...
Full-text available
Prematurity is one of the most crucial risk factors negatively affecting the maturation of the auditory system. Children born preterm demonstrate high rates of hearing impairments. Auditory processing difficulties in preterm children might be a result of disturbances in the central auditory system development and/or sensory deprivation due to peripheral hearing loss. To investigate auditory processing in preterm children, we utilized a set of psychoacoustic tests to assess temporal processing and speech intelligibility. A total of 241 children aged 6–11 years old (136 born preterm and 105 healthy full-term children forming the control group) were assessed. The preterm children were divided into three groups based on their peripheral hearing status: 74 normal hearing (NH group); 30 children with bilateral permanent sensorineural hearing loss (SNHL group) and 32 children with bilateral auditory neuropathy spectrum disorder (ANSD group). The results showed significantly worse performance in all tests in premature children compared with full-term children. NH and SNHL groups showed significant age-related improvement in speech recognition thresholds in noise that might signify a “bottom-up” auditory processing maturation effect. Overall, all premature children had signs of auditory processing disorders of varying degrees. Analyzing and understanding the auditory processing specificity in preterm children can positively contribute to the more effective implementation of rehabilitation programs.
... [1][2][3][4][5][6][7] The neonate's auditory system is developed and functional from 20 -25 weeks of gestational age; therefore, in the absence of a congenital abnormality, most preterm neonates can hear when admitted to the NICU. [8] An intense noise may startle the neonate and result in adverse physiological effects, such as increased blood pressure, heart rate or respiratory rate, decreased oxygen saturation and sleep disorders. [3,5,[8][9][10] Overexposure to constant high levels of noise, particularly at high frequencies, can adversely affect neurodevelopmental outcomes and auditory development, resulting in delayed speech and learning acquisition, which is often seen in the preterm population. ...
... [8] An intense noise may startle the neonate and result in adverse physiological effects, such as increased blood pressure, heart rate or respiratory rate, decreased oxygen saturation and sleep disorders. [3,5,[8][9][10] Overexposure to constant high levels of noise, particularly at high frequencies, can adversely affect neurodevelopmental outcomes and auditory development, resulting in delayed speech and learning acquisition, which is often seen in the preterm population. [8,10] In addition to noise, neonates in the NICU are exposed to other risk factors for hearing loss, such as prematurity, very low birth weight, intensive care treatment with mechanical ventilation, hypoxia, hyperbilirubinaemia and exposure to HIV and ototoxic medication, with a higher occurrence in developing countries. ...
... [3,5,[8][9][10] Overexposure to constant high levels of noise, particularly at high frequencies, can adversely affect neurodevelopmental outcomes and auditory development, resulting in delayed speech and learning acquisition, which is often seen in the preterm population. [8,10] In addition to noise, neonates in the NICU are exposed to other risk factors for hearing loss, such as prematurity, very low birth weight, intensive care treatment with mechanical ventilation, hypoxia, hyperbilirubinaemia and exposure to HIV and ototoxic medication, with a higher occurrence in developing countries. [6] The well-documented effects of noise that are seen in preterm neonates emphasise the need for investigating and reducing noise in the NICU. ...
Full-text available
Background. Noise is a known environmental stressor in the neonatal intensive care unit (NICU), as it may result in adverse effects on preterm neonates because of the unique vulnerability and physiological immaturity of their central nervous systems. Objective. To investigate noise levels in public sector NICUs in the eThekwini District, KwaZulu-Natal Province, South Africa. Methods. An analytical observational study design with purposive sampling of public sector hospitals was used. Noise was continuously measured with a sound level meter in a central location for 48 hours on 2 consecutive days (Sunday and Monday) in the four NICUs. A sample of noise sources, as well as their frequency of occurrence, was identified through direct observation and a frequency spectrum analysis using one-third octave bands. Data were analysed using descriptive and inferential statistics. Results. This study included one tertiary hospital and three regional hospitals in the eThekwini District. Mean noise levels exceeded international recommendations of an A-weighted equivalent continuous sound level (LAeq) of 45 A-weighted decibel (dBA) and an A-weighted maximum sound level (LAmax) of 65 dBA in all four hospitals. The most frequently occurring sources of noise were staff conversations (30.9%, Hospital A), device alarms (21.0%, Hospital B) and closing metal pedal bins (20.0%, Hospital B). Mean LAeqs >45 BA were found in the mid and high frequencies (250 Hz - 6 300 Hz) in all hospitals, particularly during the afternoon. Conclusion. The findings emphasise the need for continuous noise monitoring, awareness and education among healthcare professionals in the NICU. Future research should expand on existing findings and focus on interventions for noise control in NICUs.
... Responses to higher frequencies (>1000 Hz) are observed after 34 weeks. GA, as speech patterns are recognizable and learning and memory formations begin [41,42]. Development of the inner cells of the cochlea is a pre-determined, ordered process with specific topography of hair cells. ...
... Repeat stimulation leads to maladaptive behaviors, exaggerated pain, and a startle response. As the topography of neonatal neuronal pain pathways is developing, the long-term responses show hyperactivity, inability to "center" oneself, and exaggerated stress response to future minor stimuli [39,41,42]. ...
Full-text available
In utero, the growing fetus is subject to low-frequency noises. However, the high-risk neonate experiences much harsher sounds in the extrauterine environment. Despite many advances, modern Neonatal Intensive Care units cannot mimic the womb environment for preterm infants. Neonates are exposed to a stressful noisy environment where sleep is frequently interrupted and physiologic consequences alter development. Undesirable noise can be generated from simple conversation, use of equipment, overhead announcements, surrounding objects, and vibration. Noise levels above the American Academy of Pediatrics (AAP) recommendation (under 35–45 decibels [dB]) are associated with adverse outcomes and hearing loss. Noise level in the NICU is an important patient safety issue and should be regularly addressed by healthcare providers. Understanding modifiable and non-modifiable noise can influence daily practices, NICU design, staff education, and unit-specific quality improvement programs.
... 6 During a critical period of brain development, preterm infants in the neonatal intensive care unit (NICU) are exposed to abnormal sensory experiences and simultaneously deprived of customary sensory experiences, which may affect their long-term development. [7][8][9] To promote optimal brain development after preterm birth, researchers have suggested that developmentally relevant stimuli exposure, such as parental speaking and singing, should be offered routinely during NICU care. 10,11 Early maternal voice and music interventions in the NICU have shown beneficial short-term effects on physiological and behavioural stabilisation and brain development in preterm infants. ...
Full-text available
Aim: Studies examining the long-term effects of neonatal music interventions on the cognition of children born preterm are scarce. We investigated whether a parental singing intervention before term age improves cognitive and language skills in preterm-born children. Methods: In this longitudinal two-country Singing Kangaroo randomised controlled trial, 74 preterm infants were allocated to a singing intervention or control group. A certified music therapist supported parents of 48 infants in the intervention group to sing or hum during daily skin-to-skin care (Kangaroo care) from neonatal care until term age. Parents of 26 infants in the control group conducted standard Kangaroo care. At 2-3 years of corrected age, the cognitive and language skills were assessed with the Bayley Scales of Infant and Toddler Development, Third Edition. Results: There were no significant differences in cognitive and language skills between the intervention and control groups at the follow-up. No associations between the amount of singing and the cognitive and language scores were found. Conclusion: Parental singing intervention during the neonatal period, previously shown to have some beneficial short-term effects on auditory cortical response in preterm infants at term age, showed no significant long-term effects on cognition or language at 2-3 years of corrected age.
Background: With technological advancement, Neonatal Intensive Care Units (NICU) have become noisier than ever. Studies have shown the detrimental effects of increasing noise in NICU on growing pre-term and sick neonates. The present study aimed to survey the amount of noise in one of the NICU blocks of a government tertiary care centre and explore ways to control it when dealing with these sick babies. Methods: A detailed noise survey was carried out, for February 2023, in one of the two blocks of NICU in a government tertiary-care centre. The noise measurements were performed using two "Sound Ear 3" noise meters. The analyses were done in Leq (equivalent continuous sound levels) A-weighted decibels (dBA). Results: The extracted data analysis revealed that the NICU block was exposed to a mean Leq of 67.78 dBA noise with a maximum of 89.0 dBA. There was a significant difference between the values noted in devices at different locations and across different periods. There were certain instances (57 and 42 for two devices) when there were sudden spikes in the noise levels beyond 80 dBA. It was also seen that noise was more than 65 dBA most of the time (72% and 66% for the two devices). Conclusion: The noise survey carried out over one month revealed a considerable amount of noise in the NICU of a government tertiary-care centre. The study also explored ways such as environmental modification, human behavior modification, awareness programs, and neonatal-centered modifications to reduce the noise and lower its detrimental effects on the growth of neonates.
Full-text available
Background: Preterm birth interferes with brain maturation, and subsequent clinical events and interventions may have additional deleterious effects. Music as therapy is offered increasingly in neonatal intensive care units aiming to improve health outcomes and quality of life for both preterm infants and the well-being of their parents. Systematic reviews of mixed methodological quality have demonstrated ambiguous results for the efficacy of various types of auditory stimulation of preterm infants. A more comprehensive and rigorous systematic review is needed to address controversies arising from apparently conflicting studies and reviews. Objectives: We assessed the overall efficacy of music and vocal interventions for physiological and neurodevelopmental outcomes in preterm infants (< 37 weeks' gestation) compared to standard care. In addition, we aimed to determine specific effects of various interventions for physiological, anthropometric, social-emotional, neurodevelopmental short- and long-term outcomes in the infants, parental well-being, and bonding. Search methods: We searched Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PsycINFO, Web of Science, RILM Abstracts, and ERIC in November 2021; and Proquest Dissertations in February 2019. We searched the reference lists of related systematic reviews, and of studies selected for inclusion and clinical trial registries. Selection criteria: We included parallel, and cluster-randomised controlled trials with preterm infants < 37 weeks` gestation during hospitalisation, and parents when they were involved in the intervention. Interventions were any music or vocal stimulation provided live or via a recording by a music therapist, a parent, or a healthcare professional compared to standard care. The intervention duration was greater than five minutes and needed to occur more than three times. Data collection and analysis: Three review authors independently extracted data. We analysed the treatment effects of the individual trials using RevMan Web using a fixed-effects model to combine the data. Where possible, we presented results in meta-analyses using mean differences with 95% CI. We performed heterogeneity tests. When the I2 statistic was higher than 50%, we assessed the source of the heterogeneity by sensitivity and subgroup analyses. We used GRADE to assess the certainty of the evidence. Main results: We included 25 trials recruiting 1532 infants and 691 parents (21 parallel-group RCTs, four cross-over RCTs). The infants gestational age at birth varied from 23 to 36 weeks, taking place in NICUs (level 1 to 3) around the world. Within the trials, the intervention varied widely in type, delivery, frequency, and duration. Music and voice were mainly characterised by calm, soft, musical parameters in lullaby style, often integrating the sung mother's voice live or recorded, defined as music therapy or music medicine. The general risk of bias in the included studies varied from low to high risk of bias. Music and vocal interventions compared to standard care Music/vocal interventions do not increase oxygen saturation in the infants during the intervention (mean difference (MD) 0.13, 95% CI -0.33 to 0.59; P = 0.59; 958 infants, 10 studies; high-certainty evidence). Music and voice probably do not increase oxygen saturation post-intervention either (MD 0.63, 95% CI -0.01 to 1.26; P = 0.05; 800 infants, 7 studies; moderate-certainty evidence). The intervention may not increase infant development (Bayley Scales of Infant and Toddler Development (BSID)) with the cognitive composition score (MD 0.35, 95% CI -4.85 to 5.55; P = 0.90; 69 infants, 2 studies; low-certainty evidence); the motor composition score (MD -0.17, 95% CI -5.45 to 5.11; P = 0.95; 69 infants, 2 studies; low-certainty evidence); and the language composition score (MD 0.38, 95% CI -5.45 to 6.21; P = 0.90; 69 infants, 2 studies; low-certainty evidence). Music therapy may not reduce parental state-trait anxiety (MD -1.12, 95% CI -3.20 to 0.96; P = 0.29; 97 parents, 4 studies; low-certainty evidence). The intervention probably does not reduce respiratory rate during the intervention (MD 0.42, 95% CI -1.05 to 1.90; P = 0.57; 750 infants; 7 studies; moderate-certainty evidence) and post-intervention (MD 0.51, 95% CI -1.57 to 2.58; P = 0.63; 636 infants, 5 studies; moderate-certainty evidence). However, music/vocal interventions probably reduce heart rates in preterm infants during the intervention (MD -1.38, 95% CI -2.63 to -0.12; P = 0.03; 1014 infants; 11 studies; moderate-certainty evidence). This beneficial effect was even stronger after the intervention. Music/vocal interventions reduce heart rate post-intervention (MD -3.80, 95% CI -5.05 to -2.55; P < 0.00001; 903 infants, 9 studies; high-certainty evidence) with wide CIs ranging from medium to large beneficial effects. Music therapy may not reduce postnatal depression (MD 0.50, 95% CI -1.80 to 2.81; P = 0.67; 67 participants; 2 studies; low-certainty evidence). The evidence is very uncertain about the effect of music therapy on parental state anxiety (MD -0.15, 95% CI -2.72 to 2.41; P = 0.91; 87 parents, 3 studies; very low-certainty evidence). We are uncertain about any further effects regarding all other secondary short- and long-term outcomes on the infants, parental well-being, and bonding/attachment. Two studies evaluated adverse effects as an explicit outcome of interest and reported no adverse effects from music and voice. Authors' conclusions: Music/vocal interventions do not increase oxygen saturation during and probably not after the intervention compared to standard care. The evidence suggests that music and voice do not increase infant development (BSID) or reduce parental state-trait anxiety. The intervention probably does not reduce respiratory rate in preterm infants. However, music/vocal interventions probably reduce heart rates in preterm infants during the intervention, and this beneficial effect is even stronger after the intervention, demonstrating that music/vocal interventions reduce heart rates in preterm infants post-intervention. We found no reports of adverse effects from music and voice. Due to low-certainty evidence for all other outcomes, we could not draw any further conclusions regarding overall efficacy nor the possible impact of different intervention types, frequencies, or durations. Further research with more power, fewer risks of bias, and more sensitive and clinically relevant outcomes are needed.
A multilayered bidirectional associative memory neural network is proposed to account for learning nonlinear types of association. The model (denoted as the MF-BAM) is composed of two modules, the Multi-Feature extracting bidirectional associative memory (MF), which contains various unsupervised network layers, and a modified Bidirectional Associative Memory (BAM), which consists of a single supervised network layer. The MF generates successive feature patterns from the original inputs. These patterns change the relationship between the inputs and targets in a way that the BAM can learn. The model was tested on different nonlinear tasks, such as the N-bit, Double Moon and its variants, and the 3-class spiral task. Behaviors were reported through learning errors, decision zones, and recall performances. Results showed that it was possible to learn all tasks consistently. By manipulating the number of units per layer and the number of unsupervised network layers in the MF, it was possible to change the level of nonlinearity observed in the decision boundaries. Furthermore, results indicated that different behaviors were achieved from the same set of inputs by using the different generated patterns. These findings are significant as they showed how a BAM-inspired model could solve nonlinear tasks in a more cognitively plausible fashion.
Full-text available
Background An increasingly 24/7 connected and urbanised world has created a silent pandemic of noise-induced hearing loss. Ensuring survival to children born (extremely) preterm is crucial. The incubator is a closed medical device, modifying the internal climate, and thus providing an environment for the child, as safe, warm, and comfortable as possible. While sound outside the incubator is managed and has decreased over the years, managing the noise inside the incubator is still a challenge. Method Using active noise cancelling in an incubator will eliminate unwanted sounds (i.e., from the respirator and heating) inside the incubator, and by adding sophisticated algorithms, normal human speech, neonatal intensive care unit music-based therapeutic interventions, and natural sounds will be sustained for the child in the pod. Applying different methods such as active noise cancelling, motion capture, sonological engineering. and sophisticated machine learning algorithms will be implemented in the development of the incubator. Projected Results A controlled and active sound environment in and around the incubator can in turn promote the wellbeing, neural development, and speech development of the child and minimise distress caused by unwanted noises. While developing the hardware and software pose individual challenges, it is about the system design and aspects contributing to it. On the one hand, it is crucial to measure the auditory range and frequencies in the incubator, as well as the predictable sounds that will have to be played back into the environment. On the other, there are many technical issues that have to be addressed when it comes to algorithms, datasets, delay, microphone technology, transducers, convergence, tracking, impulse control and noise rejection, noise mitigation stability, detection, polarity, and performance. Conclusion Solving a complex problem like this, however, requires a de-disciplinary approach, where each discipline will realise its own shortcomings and boundaries, and in turn will allow for innovations and new avenues. Technical developments used for building the active noise cancellation-incubator have the potential to contribute to improved care solutions for patients, both infants and adults. Code available at: 10.3389/fped.2023.1187815 .
Aim: To investigate whether rightward attention to the mouth during audiovisual speech perception may be a behavioral marker for early brain development, we studied very preterm and low birthweight (VLBW) and typically developing toddlers (TD). Methods: We tested the distribution of gaze points in Japanese-learning TD and VLBW toddlers when exposed to talking, silent, and mouth moving faces at 12, 18, and 24 months (corrected age). Each participant was categorized based upon the area they gazed at most (Eye-Right, Eye-Left, Mouth-Right, Mouth-Left) per stimulus per age. A log-linear model was applied to three-dimensional contingency tables (region, side, group). Results: VLBW toddlers showed fewer gaze points than TD toddlers. At 12 months, more VLBW toddlers than TD toddlers showed left attentional bias toward any one face; however, this difference in attention asymmetry receded somewhat by 24 months. In talking condition, TD toddlers showed right attentional bias from 12 to 24 months, whereas VLBW toddlers showed such bias upon reaching 24 months. Additionally, more TD toddlers than VLBW toddlers attended to the mouth. Conclusion: Delays in exhibiting the attentional bias for an audiovisual face or general faces displayed by typically developing children might suggest differential developmental timing for hemispheric specialization or dominance.
Synopsis According to the World Health Organization, ∼15 million children are born prematurely each year. Many of these infants end up spending days to weeks in a neonatal intensive care unit (NICU). Infants who are born prematurely are often exposed to noise and light levels that affect their auditory and visual development. Children often have long-term impairments in cognition, visuospatial processing, hearing, and language. We have developed a rodent model of NICU exposure to light and sound using the Mongolian gerbil (Meriones unguiculatus), which has a low-frequency human-like audiogram and is altricial. To simulate preterm infancy, the eyes and ears were opened prematurely, and animals were exposed to the NICU-like sensory environment throughout the gerbil’s cortical critical period of auditory development. After the animals matured into adults, auditory perceptual testing was carried out followed by auditory brainstem response recordings and then histology to assess the white matter morphology of various brain regions. Compared to normal hearing control animals, NICU sensory-exposed animals had significant impairments in learning at later stages of training, increased auditory thresholds reflecting hearing loss, and smaller cerebellar white matter volumes. These have all been reported in longitudinal studies of preterm infants. These preliminary results suggest that this animal model could provide researchers with an ethical way to explore the effects of the sensory environment in the NICU on the preterm infant’s brain development.
Full-text available
in order to explore and understand the forces that shape early cognitive, social and emotional processes, increasing numbers of researchers are eavesdropping on the fetus evolving interaction between the fetus and the maternal environment / maternal voice sound in the fetal environment and early auditory responsiveness function of prenatal experience / neural development / speech perception and voice recognition / cognitive development / social/emotional development methodological issues / method for measurement of newborn auditory discrimination, based on differential contingent sucking patterns (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Full-text available
Auditory stimuli (a buzzer and rattle) and a tactile stimulus (a plastic filament) were repeatedly presented to 18 term and 18 preterm infants. Both groups initially responded to all stimuli with increased limb movements and heart rate acceleration. However, only the term infants responded to stimulus repetition by decreasing both cardiac and behavioral responses. In addition, they differentially responded to the 3 stimuli and showed response recovery in both systems. Since a behavioral response decrement was observed without a cardiac response decrement in the preterm group, a 2nd experiment was conducted. Heart rate change during the sucking activity of Exp II revealed an integration between autonomic and motor responsivity of preterm infants comparable to that of term newborns. The lack of cardiac–behavioral response integration during Exp I is discussed in the context of state differences between preterm and term infants as well as potential immaturity or some insult experienced by the preterm infants. The stimulus discrimination and habituation demands of Exp I may have overtaxed the preterm infants' ability to maintain response integration. (23 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The internal sound pressure levels within the intact amnion of pregnant ewes surgically implanted with a hydrophone was determined during conditions of quiet and during sound field exposures to broadband and octave-band noise. Measurements were made of sound pressures outside and inside the ewe, and sound attenuation through maternal tissues and fluids was calculated. Sound pressures generated by low frequencies (less than 0.25 kHz) were 2 to 5 dB greater inside than outside the ewe. Above 0.25 kHz, sound attenuation increased at a rate of 6 dB per octave. For 4.0 kHz, sound attenuation averaged 20 dB. The sound pressure recorded at different locations within the amnion with respect to the sound source varied by up to 6 dB. The internal noise floor in the absence of externally generated sounds was as low as 50 dB (spectrum level) above 0.2 kHz. Thus the fetus is developing in an environment that is rich with internal and external sounds.
The development of language has classically been under­ stood within a cognitive context. Yet the musical elements of speech represent perhaps the most personal part of human expression. Expressive sounds impact the content of spoken words and characterize distinct feelings. This article presents a rationale for the musical development of speech and a means of understanding the level of vocal activity that occurs in a pre-verbal context. The Model identifies three Musical Stages of Speech: Stage I, Cry­ ing/Comfort Sounds; Stage II, Babbling, Lalling, and In­ flected Vocal Play; Stage III, Single­ and Double-Word Utterances. At each stage of language acquisition, specific techniques that enhance vocalizing are offered in order to sequentially build upon each developmental level. The Musical Stages of Speech integrate the cognitive, physical, and emotional components of development through the identification of musical elements that stratify levels of pre-verbal speech.
The intrauterine environment presents a rich array of sensory stimuli to which the fetus responds. The maternal voice is perhaps the most salient of all auditory stimuli. The following experiments examined the movement response of the fetus and newborn to its mother's voice and a strange female's voice and to voices speaking normally and speaking 'motherese'. Newborns (2-4 days of age) discriminated, as measured by the number of movements exhibited to the presentation of the stimuli, between their mother's voice and a stranger's voice and between normal speech and 'motherese', in both cases the former being preferred. Fetuses, 36 weeks of gestational age, evidenced no ability to discriminate between their mother's and a stranger's voice played to them via a loudspeaker on the abdomen but did discriminate between their mother's voice when played to them by a loudspeaker on the abdomen and the mother's voice produced by her speaking. The results are further evidence of the ability of the fetus to learn prenatally and indicate a possible role for prenatal experience of voices in subsequent language development and attachment.
Purpose: To evaluate the clinical significance of differences in 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) lymph node standardized uptake values (SUV) in human immunodeficiency virus (HIV) infection using iterative reconstruction with segmented attenuation correction (IR SAC) compared to filtered back-projection with measured attenuation correction (FBP MAC).Procedures: Seven patients with HIV infection and multiple focal lymph node abnormalities were investigated with whole-body FDG-PET. Mean and maximum SUVs from lymph node regions of interest (n = 961) were compared for quantitative differences between reconstruction techniques.Results: IR MAC resulted in significantly lower mean SUV [0.06; 95% (confidence interval (CI)) = 0.04–0.07] and maximum SUV (0.82; 95% CI = 0.77–0.88) values compared to FBP MAC. With IR, segmentation of attenuation correction (AC) resulted in significantly higher mean SUV (0.12; 95% CI = 0.11–0.13) and maximum SUV (0.21; 95% CI = 0.18–0.23) values compared to IR MAC. The overall effect of both IR and SAC was a slight but significant increase in mean SUV (0.06; 95% CI = 0.06–0.08; bias = 2.1%) and a significant decrease in maximum SUV (0.62; 95% CI = 0.56–0.67) compared to FBP MAC.Conclusions: With our reconstruction parameters, significant differences in mean and maximum SUV values were observed. The magnitude of the mean SUV difference, however, was small. IR SAC is a promising method to accurately quantify standardized uptake values for clinical use.
Continuous loud noice was used to mask auditory feedback from vocal behavior of male canaries. Single unit techniques demonstrate partial deafness after noise exposure. Longer exposure caused greater deficits, with losses of high-frequency sensitivity. Males raised in noise to 40 days of age, then deafened surgically, thus totally deprived of auditory feedback from vocalization, developed significantly fewer song syllables than birds similarly raised but left intact, to mature in quiet sound-insulated chambers. Males left longer in noise, to sexual maturity at 200 days of age, sang at first like surgically deafend birds, but then increased their song syllable repertoire after noise termination. Thus, in spite of the considerable deafness resulting from noise exposure, the deficit in syllable repertoire was corrected, presumably as a result of restoration of the birds' ability to hear their own song.