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Developmental Science 7:5 (2004), pp 550–559
© Blackwell Publishing Ltd. 2004, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA.
T553Blackwell Publishing, Ltd.
REPORT
Maturation of fetal responses to music
Maturation of fetal responses to music
B.S. Kisilevsky,1 S.M.J. Hains,1 A.-Y. Jacquet,2 C. Granier-Deferre2 and
J.P. Lecanuet2
1. Queen’s University and Kingston General Hospital, Kingston, Canada
2. Université Paris V, Paris, France
Abstract
Maturation of fetal response to music was characterized over the last trimester of pregnancy using a 5-minute piano recording
of Brahms’ Lullaby, played at an average of 95, 100, 105 or 110 dB (A). Within 30 seconds of the onset of the music, the
youngest fetuses (28–32 weeks GA) showed a heart rate increase limited to the two highest dB levels; over gestation, the threshold
level decreased and a response shift from acceleration to deceleration was observed for the lower dB levels, indicating attention
to the stimulus. Over 5 minutes of music, fetuses older than 33 weeks GA showed a sustained increase in heart rate; body movement
changes occurred at 35 weeks GA. These findings suggest a change in processing of complex sounds at around 33 weeks GA,
with responding limited to the acoustic properties of the signal in younger fetuses but attention playing a role in older fetuses.
Introduction
In recent years, parents as well as scientists have become
increasingly interested in fetal perception and cognition.
In a cross-cultural survey of maternal knowledge and
beliefs concerning fetal development conducted in France
and Canada, investigators (Kisilevsky, Beti, Hains &
Lecanuet, 2001) found that many mothers-to-be believe
that all perceptual systems are developed by about 25
weeks gestational age (GA). The majority of the re-
spondents also believe that fetuses react to music about
1 week later and about half believe that fetuses have
emotions and thoughts. Moreover, there is a common
belief that playing music to fetuses and infants increases
intelligence. The evidence for a positive effect of music
on infant development is mostly anecdotal and is perhaps
reinforced by a plethora of commercial audio-recordings
(e.g. music, heart sounds) and devices purported to
enrich the fetal environment and increase infant IQ.
Although it is difficult to find any scientific evidence
for the ‘music for a better brain’ claim, Gray et al. (2001)
argue that there is a biological and evolutionary origin
of musical ability, and according to Tramo (2001), all of
us are born with the capacity to apprehend emotion and
meaning in music. If so, then this capacity should be
present in near-term fetuses. We know that fetuses can
hear by the last trimester of pregnancy (e.g. Kisilevsky,
Pang & Hains, 2000) and that music played in the
external environment is recognizable in utero (Querleu,
Renard, Boutteville & Crepin, 1989). There is some evid-
ence that term fetuses can distinguish between voices
(mother versus stranger, Kisilevsky et al., 2003; male
versus female, Lecanuet et al., 1993) and musical notes
(piano D4 versus C5, Lecanuet, Granier-Deferre, Jacquet
& DeCasper, 2000) as well as habituate to a brief piano
sequence with changing melodic contour (Granier-Deferre,
Bassereau, Jacquet & Lecanuet, 1998).
While there has been very little work in the area of
fetal perception of music per se, fetal auditory percep-
tion is well described. By about 30 weeks GA, fetuses
begin to respond to brief episodes (2–3 seconds) of relat-
ively loud (110 dB sound pressure level [SPL]) airborne
sounds with heart rate acceleration and body movement
responses (Kisilevsky et al., 2000). As gestation advances,
the frequency and magnitude of responses increases and
the threshold for a response decreases. At term, the com-
plexity of the stimulus (pure tone, white noise, speech) as
well as its intensity and frequency regulate the threshold
and magnitude of a response (see Lecanuet, Granier-
Deferre & Busnel, 1995 and reviews by Lecanuet &
Schaal, 1996 and Kisilevsky & Low, 1998). Clearly, by
late gestation the fetus can hear, and fetal auditory
perceptual abilities become more sensitive with the
maturation of the auditory system.
Address for correspondence: B.S. Kisilevsky, 90 Barrie Street, Kingston, ON K7L 3N6, Canada; e-mail: kisilevb@post.queensu.ca
Maturation of fetal responses to music 551
© Blackwell Publishing Ltd. 2004
The studies on the development of fetal hearing have
used brief bursts of noise emitted over seconds rather
than prolonged noise over a period of time as would be
more typical of environmental sounds such as music.
However, some previous studies have examined the
effects of music on fetal behaviour using longer episodes
of stimulation. Sontag, Steele & Lewis (1969) played a
10-minute tape-recorded passage of the mother’s favour-
ite piece of music through two floor speakers placed at
the foot of a bed; intensity averaged 75 dB (range 65 dB
to 100 dB) measured at the mother’s head. In fetuses
from 28 weeks GA to term (n = 11), they found that a
significant cardiac acceleration (about 5 beats per
minute) occurred 90 seconds after music onset. There
were no changes in fetal body movements and no change
in maternal heart rate. Fetal heart rate returned to base-
line within 2 minutes of music onset. Because the onset
of the response was delayed and there was no change in
activity, the authors speculated that fetal response was
mediated through the emotional reaction of the mother.
Similarly, Zimmer et al. (1982) posited that changes in
fetal behaviour were mediated by maternal hormonal
changes when they played music via headphones to
pregnant women at 34 – 40 weeks gestation (i.e. masked
to the fetus). They found that fetuses showed decreased
breathing activity and increased body movements if the
mother listened to a preferred type of music (classical
versus rock).
Other early attempts to characterize the effects of
music on fetal behaviour were unsuccessful. Olds (1985a,
1985b) played various classical music pieces to fetuses
from 30 weeks GA via headphones placed on the mater-
nal abdomen. He noted that variability in fetal heart rate
occurred during the music. However, fetal responses
were not uniform, with heart rate increasing for some
and decreasing for others, and statistical tests were not
reported. It may be that Olds’ fetal results were con-
founded by maternal responses, for Olds did not mask
the music to the mother so that fetal behaviour could
have been influenced by maternal emotional response.
While the results of Olds’ work are equivocal, Hepper
(1991) demonstrated limited fetal and newborn response
to music in a series of studies examining learning before
and after birth. For fetuses and newborns the procedure
was similar: a no-music baseline period followed by a 3-
minute music period with statistical comparisons between
either a 30-second baseline and the last 30 seconds of
the music period (newborns) or a 1-minute baseline and
the last minute of the music period (fetuses). An increase
in body movements was elicited by the theme song of a
television soap opera in a group of 36–37 weeks GA
fetuses whose mothers had watched the programme
throughout their pregnancies, but not in a group of
younger fetuses, 29–30 weeks GA, or a group whose
mothers had not watched the programme. Two- to 4-
day-old newborns showed the opposite response, a
decrease in movement and heart rate and the adoption
of an alert state. However, they showed no change in
behaviour when the theme song was played backwards
or when a theme song of a programme their mother
had not watched during pregnancy was played. At 21
days of age, infants whose mothers had not watched the
programme since delivery showed no response to the
theme tune. Taken together, these findings indicate that
fetal response to a particular piece of music is experience-
dependent, and experience with the music must be con-
tinued after birth for the response to continue.
The results of studies examining the effects of music
on newborns and premature infants could indicate the
capabilities of fetuses of equivalent GA. Findings from
studies of the development of active cochlear mechan-
isms in premature infants demonstrate that otoacoustic
emissions (OAE) indicating outer hair cell activity begin
at about 30 weeks conceptual age (Morlet et al., 1995)
with functional maturation nearly complete by 33 weeks
(Morlet, Collet, Salle & Morgon, 1993). A lack of activity
in the medial olivocochlear system indicates functional
immaturity in the auditory pathway relaying information
to the cortex (Morlet et al., 1993). Thus, it is unlikely that
fetuses of less than 33 weeks GA are capable of the
higher order processing necessary for complex auditory
stimuli and music in particular. Nevertheless, music has
been shown to have positive effects on premature infant
behaviour. From 31 weeks GA, premature infant behavi-
ours (i.e. heart rate, state-of-arousal, facial expressions
of pain) returned to baseline more rapidly when Brahms’
Lullaby (vocal or piano) was played immediately follow-
ing heel lance (Butt & Kisilevsky, 2000) than in a no-
music comparison condition. The results of non-contingent
music in the premature nursery environment are equivo-
cal. Playing 10 minutes of non-contingent music in the
isolette, Lorch, Lorch, Diefendorf and Earl (1994) found
that premature infants were excited (increased heart
rate) or quieted (decreased heart rate) by different music
pieces. In contrast, when female vocalist recordings of
lullabies were delivered via headphones for 20 minutes
over three consecutive days, Standley and Moore (1995)
found that oxygen saturation increased during music on
day 1 only and decreased in the post-music period on
days 2 and 3. While the outcome of playing non-contingent
music in the premature nursery is equivocal, Kaminski
and Hall (1996) suggest that it is beneficial in the normal
newborn nursery (i.e. full-term infants). During a 6-
hour observation, including both a no-music and a music
period, they found fewer high arousal states and fewer
state changes during music compared to no-music.
552 B.S. Kisilevsky et al.
© Blackwell Publishing Ltd. 2004
Kaminski and Hall chose Brahms’ Lullaby for their
study because the tempo approximated the rate of the
maternal heartbeat, 65–80 beats per minute, which
DeCasper and Sigafoos (1983) had shown to be an effect-
ive reinforcer for infants in an operant learning task,
presumably because of their previous experience. DeCasper
and Carstens (1981) also found that newborns modulate
their sucking to elicit music if they have had prior con-
tingent experience with it (i.e. previous experience with
producing vocal music by increasing the inter-burst
interval of non-nutritive sucking) but not if the experi-
ence was non-contingent.
Although music has a number of characteristics that
affect adult response (e.g. pitch, rhythm, tempo; Parsons,
2001), little is known about how they affect fetal re-
sponses. Lecanuet and colleagues have demonstrated
that fetuses can discriminate two low-pitched musical
notes (Lecanuet et al., 2000) and two different tempi
(Lecanuet, unpublished data). In older infants, a higher
pitch is more effective in capturing and holding atten-
tion (Trainor & Zacharias, 1998) while variations in
tempo can excite (fast) or soothe (slow) (Trehub, Hill &
Kamenetsky, 1997).
In summary, while it appears that near-term fetuses
respond to a music stimulus which has been repeatedly
presented in the environment and that fetuses can dis-
criminate some characteristics of music (e.g. notes, tempi)
that affect adult responses, no studies have systematic-
ally examined fetal perception of a music stimulus over
gestational age. Thus, third trimester development of
auditory perception using a music stimulus will be exam-
ined in the present study as well as the effects of vari-
ations in tempo on fetal behaviour. For this first step in
characterizing the maturation of fetal perception of a
music stimulus, we chose to use Brahms’ Lullaby because
of its successful use with premature and full-term infants
as noted above.
Method
Participants
A total of 122 fetuses of women experiencing a low-risk,
uneventful pregnancy were tested on one occasion. Gesta-
tional age was determined from last menstrual period
if periods were reliable (accuracy rate 75–85%) and/or
from early ultrasound scan (SD = ±1 week). Forty-seven
28–38 weeks GA fetuses were recruited from antenatal
clinics at a teaching hospital in southern Ontario, Can-
ada. The data from two fetuses were eliminated because
of preterm birth. The remaining 45 fetuses were born
healthy at term (i.e. 5-minute Apgar score of 8 –10, birth-
weight > 10th percentile for gestational age and healthy
on physical examination). There were 26 male and
19 female infants with an average birthweight of 3582
grams (SD ± 459 grams). Maternal age averaged 28.5
years (SD = 4.3 years); 56% were primiparous; and 84%
had vaginal deliveries. Seventy-five term fetuses (38–41
weeks GA) were recruited from prenatal information
sessions at the Port-Royal University Clinic of Paris,
France. All fetuses were born healthy at term (i.e. birth-
weight > 10th percentile for gestational age). There were
44 male and 31 female infants, with an average birth-
weight of 3361 grams (SD ± 447 grams). Maternal age
averaged 30.3 years (SD = 5.3); 87% were primiparous;
and 80% had vaginal deliveries. Sixty-nine had complete
data and were included in analyses. At both sites, gender
was determined at delivery and studies were carried out
following institutional research ethics board approval.
Equipment/stimuli
The 5-minute piano music stimuli consisted of three tape
recordings of Brahms’ Lullaby (Op. 49, No. 4 in D flat
major) generated for the study. In Kingston, a tape of
the music at a tempo of 69 beats per minute was played
on a TASCAM DAT 20 system, amplified (University
amplifier) and delivered through a Auratone 5C Super-
Sound Cube loudspeaker. Instantaneous sound levels
were measured in-air, at a distance of 10 centimetres
from the loudspeaker, using the A scale of a Bruel &
Kjaer Impulse Precision Sound Level Meter model
2235. Fetal heart rate was recorded continuously using a
Hewlett Packard 1040 A cardiotachograph, with an
event marker to indicate trial onset. To obtain a fetal
heart rate for each second, records were scored using an
Abaton Macintizer ADB digitizing tablet connected to a
Macintosh computer (for details see Coleman, Kisilevsky
& Muir, 1993). The sampling rate was set at 10 times per
second with the average of the 10 scores becoming the
fetal heart rate for that second. Body movements were
ultrasonographically visualized using an ATL Ultramark
4 and video-recorded.
In Paris, two tapes of the music, one at 69 beats per
minute and one at 118 beats per minute, were played on
a JVC TD-W118BK dual cassette player through a BST
Stereo Mixer – MR60 and delivered via a loudspeaker
(AUDAX HR37) supported by a movable C-shaped table
placed 20 centimetres above the maternal abdomen.
Average sound levels (Leq) were measured in-air, at a
distance of 20 centimetres from the loudspeaker, using
an ACLAN Sound Level Meter model SDH80. Ana-
logic fetal heart rate data were collected from a Hewlett
Packard series 50 A cardiotacograph via a combined
interface module (J10) connected to a PC Lab A/D
Maturation of fetal responses to music 553
© Blackwell Publishing Ltd. 2004
board to be sampled at a rate of 10 values/s and stored
into an IBM compatible computer. Fetal heart rate in
beats per minute computed by the cardiotacograph was
continuously displayed in digital and analogic formats.
Body movements were ultrasonographically visualized
using an ALOKA SSD 500 and video-recorded.
The cardiotacographs and real-time ultrasound equip-
ment at both sites are comparable and yield similar data.
Instantaneous and averaged sound level measurements
in Kingston comparing the Bruel & Kjaer and ACLAN
instruments (A scale) showed both stimulus measure-
ments to be similar: instantaneous 95 dB = 95.2 dB Leq
over 1 minute; instantaneous 105 dB = 105 dB Leq over
1 minute; instantaneous 110 dB = 109.8 dB Leq over 1
minute. The principal investigator conducted all studies
in Kingston and testing of the first 43 subjects in Paris.
Procedure
Each fetus received one or two episodes of a 5-minute
piano recording of Brahms’ Lullaby, preceded and fol-
lowed by 5 minutes of a no-sound control period. The
music was delivered at an average sound level of 95 dB,
100 dB, 105 dB or 110 dB (A) through a loud speaker
located about 10 (Kingston) or 20 (Paris) centimeters
above the maternal abdomen. In Paris, two variations in
tempo (‘normal’, 69 beats per minute, and ‘fast’, 118
beats per minute) were included; tempo was counter-
balanced over subjects. Fetal heart rate was recorded
continuously for all subjects. Body movements were
video-recorded from a cross sectional view of the fetal
abdomen which may or may not have contained limbs.
Movement data were collected for all Kingston subjects
and for the first 31 subjects recruited in Paris, where
technical difficulties precluded the video-recording of
body movements for subsequent subjects. During the
procedure, mothers wore headphones through which
either vocal country (Kingston) or guitar (Paris) music
was used as an effective mask.
Data manipulation
In keeping with our previous work, for analyses by age
the following age groupings were used: 28 weeks 0 days
to 32 weeks 6 days; 33 weeks 0 days to 34 weeks 6 days;
35 weeks 0 days to 36 weeks 6 days; and greater than
37 weeks. The number of participants in each condition
by age group are displayed in Table 1. Although data
for most fetuses was recorded for 300 seconds in each
period, some variability existed in recording time, hence
data for only 280 seconds were analysed for each period.
Fetal body movements were scored from the video-
tapes and included any observed movement of the body
or limbs. The latency to the first movement following
the onset and offset of the music was determined. The
number of body movements and their duration within
each 30 seconds of each period were calculated. Because
there is no precedent to guide us in the analyses of fetal
heart rate, all data for every participant were used in the
initial analysis ignoring GA and sound level to find if
there is an overall effect of music. In an effort to replicate
the analyses performed on vibroacoustic (e.g. Kisilevsky,
Muir & Low, 1992) and white noise (Kisilevsky et al.,
2000) stimuli in previous studies, the data for the first 30
seconds following music onset and offset were compared
to the data for the previous 30 seconds to examine the
short-term effects of the music. To examine longer-term
effects, following the example of Kisilevsky et al. (2003)
who used the second-by-second heart rate data for the
complete period following the onset and offset of the
maternal voice, the heart rates for each second were used
in the analyses of the present data.
Results
Movement
When all available data were considered using a 1 between
(age: three levels) 2 within (three periods, ten 30-second
time intervals) ANOVA, more of the younger fetuses
(< 35 weeks GA) moved than the older fetuses, F(1, 88)
= 7.81, p < .01, although there were no significant differ-
ences in duration of movement or latency to the first
movement between the three periods, neither was there
an immediate movement response in the first 30 seconds
after stimulus onset. When each age group was exam-
ined separately, the younger fetuses did not show any
change in the duration of movements across periods
(4.21 seconds, 4.28 seconds, 4.48 seconds). However,
as shown in Figure 1, during the music period, older
fetuses (> 35 weeks GA), showed a change in the number
of fetuses demonstrating a body movement from 32%
at onset to 55% after 3 minutes, before dropping to 27%
Table 1 The number of participants in each decibel by
age group
Sound level
Age group Tempo 95 dB 100 dB 105 dB 110 dB
28–32 weeks GA normal 5 6 6
33–34 weeks GA normal 6 6 6
35–36 weeks GA normal 14 8 8
Term normal 11 12 11
1/3rd faster 12 12 11
554 B.S. Kisilevsky et al.
© Blackwell Publishing Ltd. 2004
by the end of the period (quadratic change over time,
F(1, 54) = 19.75, p < .01). The duration of movements
changed from 2.7 to 5.3 seconds after 3 minutes before
dropping to 2.5 seconds by the end of the period (quad-
ratic change over time, F(1, 54) = 8.67, p < .01). No effects
of sound level or tempo were seen.
Heart rate preliminary analyses
As there is a correlation between body movement and
fetal heart rate accelerations, it is possible that any
increase in fetal heart rate could be attributed to
increased body movement. To test this possibility, the
average heart rate for each 30 seconds of the music
period was analysed using the presence or absence of a
body movement in the same 30 seconds as a covariate.
This 2 between (GA, dB), 1 within (10 levels of time)
analysis showed an effect of body movement on fetal
heart rate, F(1, 36) = 6.49, p < .05, but there was also a
main effect of time, F(9, 36) = 2.03, p < .05, indicating
that the increase in fetal heart rate over time cannot be
attributed to fetal movements alone.
The immediate effect of music was examined by com-
paring the second-by-second data for the last 30 seconds
pre-music with the first 30 seconds following music
onset, using a 2 between (age, dB), 2 within (two periods,
30 seconds) ANOVA. There was a significant time ×
period effect, F(29, 3509) = 3.27, p < .01; and a time ×
period × dB triple interaction, F(87, 3509) = 1.33, p < .01.
Music had an immediate effect on fetal heart rate.
A second-by-second data analysis for all fetuses in
each period using repeated measures (280 seconds)
ANOVA showed that the music had some effect on fetal
heart rate. For the pre-music (control) and post-music
periods, there was no overall change in fetal heart rate
over time, but in the analysis for the music period, as
shown in Figure 2, an effect of time was found,
F(279, 35 712) = 1.60, p < .01, that included a linear
increase, F(1, 128) = 7.50, p < .01. Variability was stable
over periods; the SD varied from 9.7 and 13.7 in the first
no-stimulus period to 9.7 and 13.4 in the music period
and 10.7 to 14.9 following the offset of the music.
Figure 1 Body movement in each 30-second interval
in response to hearing Brahms’ Lullaby by fetuses greater
than 35 weeks GA: (A) percentage of fetuses showing a
body movement, and (B) the mean duration of movement in
seconds.
Figure 2 Mean heart rate change for all fetuses and
sound levels over 5 minutes after the onset of Brahms’
Lullaby.
Maturation of fetal responses to music 555
© Blackwell Publishing Ltd. 2004
Maturation of heart rate responding: music period
Fetuses 28–32 weeks GA
A 1 between (dB), 1 within (time) ANOVA was con-
ducted for each age group separately, using the first
30 seconds following music onset. For the 28–32 weeks
GA group, it showed a significant time × dB interaction,
F(58, 348) = 2.26, p < .01; there was no effect on fetal
heart rate for the music played at 95 dB while there was
a linear increase for 105 dB, F(29, 116) = 2.32, p < .01;
and a rapid increase over 12 seconds followed by a
return to baseline for 110 dB, F(29, 116) = 2.59, p < .01,
as shown in Figure 3A. There was no further effect of
music on fetal heart rate for this group.
Fetuses 33–34 weeks GA
Figure 3B shows a change in heart rate during the
onset of music. The analysis of the first 30 seconds
following music onset showed a significant time × dB
interaction, F(58, 435) = 2.48, p < .01. Again, there was
no effect on fetal heart rate of music played at
95 dB, while there was a reduction in fetal heart rate
for 105 dB, F(29, 174) = 1.96, p < .01, and a gradual
increase followed by a decrease for 110 dB, F(29, 174)
Figure 3 Mean fetal heart rate change during Brahms’ Lullaby as a function of time and decibel level for preterm fetuses at:
(A) 28 – 32 weeks GA, (B) 33–34 weeks GA, and (C) 35– 36 weeks GA.
556 B.S. Kisilevsky et al.
© Blackwell Publishing Ltd. 2004
= 2.12, p < .01. Over the 5 minutes of the music period,
33–34 weeks GA fetuses showed an increase in
heart rate, F(279, 4185) = 1.23, p < .01, that had a
linear component, F(1, 15) = 4.33, p < .05, but no effect
of dB.
Fetuses 35–36 weeks GA
In the first 30 seconds after music onset there was a quad-
ratic effect for 95 dB, F(29, 203) = 2.01, p < .01, and for
110 dB, F(29, 203) = 1.80, p < .01. Over the 5-minute music
period, the 35–36 weeks GA preterm fetuses showed an
increase in heart rate, F(279, 7533) = 2.15, p < .01, that
had a linear component, F(1, 27) = 4.33, p = .05.
Term fetuses, from 37 weeks GA
The data analysis for the first 30 seconds after music
onset was performed for each tempo separately.
In the normal tempo, shown in Figure 4A, over the
first 30 seconds after onset there was a time effect,
F(29, 899) = 3.5, p < .01, that was linear, F(1, 31) = 8.1,
p < .01, with no effect of dB level. The increase peaked
at about 30 seconds followed by a return to baseline.
Over the 5-minute music period, there was no overall
increase in fetal heart rate for this group.
When the music was played a third faster, as shown in
Figure 4B, during the first 30 seconds of music there
was a main effect of time, F(29, 899) = 2.53, p < .01, and
a time × dB interaction, F(58, 899) = 1.99, p < .01. These
fetuses showed a decline in fetal heart rate followed by
an increase. The minimum occurred at about 28 seconds
for the 95 dB stimulus and at about 7 seconds for the
100 dB and 105 dB stimuli. Also, for this group, there
was an overall increase in fetal heart rate over the whole
period, F(279, 8370) = 1.43, p < .01, that had a linear
component, F(1, 30) = 4.62, p < .01.
Discussion
In this study, we demonstrated a maturation of music
perception over the last trimester of pregnancy using
both movement and heart rate measures. Body move-
ment responses were not observed until 35 weeks GA,
when both the number of fetuses showing body move-
ments and the duration of the movements increased to a
maximum after about 3 minutes of stimulation. These
findings are similar to those of Hepper (1991). In his
fetal learning study, he demonstrated an increase in body
movements over baseline at 3 minutes after the onset of
a familiar piece of music for near-term fetuses, 36–37
weeks GA, but not for a group of younger fetuses, 29 –
30 weeks GA, or for fetuses to whom the music was not
familiar. What is clear from these two studies is that
near-term fetuses can show an increase in body move-
ments when hearing music; the specific aspect of music
eliciting the increase in movements or learned by the
fetus is unknown at this time.
Fetuses in all age groups (28 weeks GA to term)
showed some heart rate response to the music stimulus,
summarized in Table 2. The maturation of cardiac
response was shown by changes in the direction of the
response as a function of fetal age and sound intensity.
Over the first 30 seconds, music at the highest sound
level generally elicited a heart rate acceleration (thought
to indicate arousal) while lower intensities elicited a
deceleration until by term all of the sound levels tested
elicited a deceleration at music onset (thought to indic-
ate attention).
Over the course of the 5-minute music period, fetuses
from 33 to 37 weeks GA showed a gradual heart rate
acceleration that did not differ over sound levels. The
term fetuses showed an increase in heart rate to the
faster tempo, whereas the lullaby played at the normal
tempo had little effect on heart rate. Both Sontag et al.
(1969) and Kisilevsky et al. (2003) examined fetal heart
rate response to continuous, prolonged airborne sounds
using music and voice stimuli respectively. In Sontag’s
music study, fetuses of varying ages responded with a
heart rate acceleration within two minutes of music
onset played at an average of 75 dB SPL. In the voice
study, term fetuses responded with an increase in heart
rate over a 2-minute period to their mothers’ voices and
a similar decrease to a stranger’s voice, both delivered at
Table 2 Direction of significant fetal heart rate changes over
age and sound level during the music period
Direction of fetal heart rate change*
Tempo
Gestational
age
Sound
level (dB)
30 s after
onset
5 min music
(all dB)
Normal 28–32 weeks 95
105 ↑
110 ↑
Normal 33–34 weeks 95 ↑
105 ↓
110 ↑
Normal 35–36 weeks 95 ↓↑
105
110 ↑
Normal Term 95 ↑
100 ↑
105 ↑
Fast Term 95 ↓↑
100 ↓
105 ↓
Note: * only statistically significant changes in fetal heart rate are shown.
Maturation of fetal responses to music 557
© Blackwell Publishing Ltd. 2004
95 dB. The sustained heart rate acceleration response to
music observed in the previous study and in this study,
as well as to the mothers’ voices (Kisilevsky et al., 2003),
may represent the influence of experience.
In adults, auditory experience changes the make-up
of areas in the cerebral cortex that are involved in the
processing of complex sounds, including music, and the
changes in auditory cortical representations are based
on activity-dependent modifications of synaptic circuitry
(Rauschecker, 2001). However, fetal music response is
probably not cortical in origin as, at this time, mature
axons are present only in the most superficial layer of
the cortex (Moore, 2002). However, processing of musi-
cal elements such as frequency (e.g. Giraud et al., 2000)
and pitch (e.g. Braun, 2000) probably occurs in the infe-
rior colliculus in adults, so that it is possible that the
fetal behaviour observed here signifies the onset of these
abilities. The maturational changes observed here may
reflect maturation of the peripheral auditory system and
physiological development of the different brainstem
auditory nuclei that will transmit basilar coding up to
the inferior colliculi (Frisina, 2001). The neural basis of
hearing begins with maturation of cochlear hair cells
over early to mid-gestation (e.g. Pujol, Lavigne-Rebillard
& Uziel, 1991; Rubel & Fritzsch, 2002). Beyond the
cochlea, there is a complexity of overlapping cell layers
in the pathways leading to the auditory cortex. In the
brain stem, path length increases (Moore et al., 1996)
and axonal conduction time reaches maturity by 40
weeks GA (Ponton, Moore & Eggermont, 1996).
The effect of tempo on the responses of the term
fetuses can be explained in terms of arousal. A faster
tempo gives rise to more activation of the cochlea and
auditory fibres, so that the differential response to tempo
by term fetuses might reflect a difference in arousal
levels as a result of more stimulation of the reticular forma-
tion. Alternatively, it may provide evidence that tempo is
a salient stimulus for term fetuses, suggesting continuity
in pre- and post-natal music perception. If the assump-
tion is made that there is continuity from fetus to new-
born, then it is also feasible that changes in the direction
of the fetal heart rate response over late gestation rep-
resent a change in processing from simple discrimination
of the signal to attention, reflecting primitive cognitive
function.
Continuity of responding before and after birth has
been demonstrated previously with brief duration (2.5
seconds) sound and vibration (e.g. Kisilevsky & Muir,
1991) and with short musical melodies (Granier-Deferre
et al., 1998). Finding a systematic change in fetal heart
rate following the onset of the music suggests that the
fetuses were aware that the music was different from
the ongoing background uterine sounds that have a
rhythmic quality (e.g. discriminating the music from the
maternal heart rate) or that the music masks these back-
ground sounds.
In summary, our findings add to the small body of
knowledge concerning fetal cognitive abilities. Although
it is difficult to demonstrate the same abilities in the
fetus that have been demonstrated with newborns, this
study has explored the time course of the origins of these
abilities. It seems that near-term fetuses are able to make
simple discriminations (i.e. renew responding or respond
differently to a change in stimulus parameter) based on
a number of dimensions (e.g. tempo, reported here; loud-
ness and pitch, Lecanuet et al., 2000), and have some
Figure 4 Mean fetal heart rate change in term fetuses as a
function of time and decibel level for Brahms’ Lullaby played
at: (A) normal tempo, and (B) one third faster.
558 B.S. Kisilevsky et al.
© Blackwell Publishing Ltd. 2004
rudimentary memory of music (Hepper, 1991) and short
speech sequences (i.e. child’s rhyme, DeCasper et al.,
1994). Also, not only can they distinguish between some
complex auditory stimuli (voices) but also respond differ-
entially to variations. Our findings characterize the mat-
uration of responding to a complex auditory stimulus
and provide evidence that higher order auditory percep-
tion begins before birth.
Acknowledgements
Parts of this paper were presented at the 12th Biennial
International Conference on Infant Studies, Brighton,
UK, July 2000. The research was funded by grants to B.S.
Kisilevsky from the Queen’s University Advisory Research
Committee and the Faculty Association as well as to
J.-P. Lecanuet and C. Granier-Deferre from the CNRS.
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Received: 11 April 2003
Accepted: 16 January 2004
