Otoacoustic emission theories and behavioral estimates of human basilar membrane motion are mutually consistent.

Unidad de Audición Computacional y Psicoacústica, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, C/Pintor Fernando Gallego 1, 37007, Salamanca, Spain.
Journal of the Association for Research in Otolaryngology (Impact Factor: 2.55). 07/2009; 10(4):511-23. DOI: 10.1007/s10162-009-0176-9
Source: PubMed

ABSTRACT When two pure tones (or primaries) of slightly different frequencies (f (1) and f (2)) are presented to the ear, new frequency components are generated by nonlinear interaction of the primaries within the cochlea. These new components can be recorded in the ear canal as otoacoustic emissions (OAE). The level of the 2f (1)-f (2) OAE component is known as the distortion product otoacoustic emission (DPOAE) and is regarded as an indicator of the physiological state of the cochlea. The current view is that maximal level DPOAEs occur for primaries that produce equal excitation at the f (2) cochlear region, but this notion cannot be directly tested in living humans because it is impossible to record their cochlear responses while monitoring their ear canal DPOAE levels. On the other hand, it has been claimed that the temporal masking curve (TMC) method of inferring human basilar membrane responses allows measurement of the levels of equally effective pure tones at any given cochlear site. The assumptions of this behavioral method, however, lack firm physiological support in humans. Here, the TMC method was applied to test the current notion on the conditions that maximize DPOAE levels in humans. DPOAE and TMC results were mutually consistent for frequencies of 1 and 4 kHz and for levels below around 65 dB sound pressure level. This match supports the current view on the generation of maximal level DPOAEs as well as the assumptions of the behavioral TMC method.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Hearing-impaired (HI) listeners often show less masking release (MR) than normal-hearing listeners when temporal fluctuations are imposed on a steady-state masker, even when accounting for overall audibility differences. This difference may be related to a loss of cochlear compression in HI listeners. Behavioral estimates of compression, using temporal masking curves (TMCs), were compared with MR for band-limited (500-4000 Hz) speech and pure tones in HI listeners and age-matched, noise-masked normal-hearing (NMNH) listeners. Compression and pure-tone MR estimates were made at 500, 1500, and 4000 Hz. The amount of MR was defined as the difference in performance between steady-state and 10-Hz square-wave-gated speech-shaped noise. In addition, temporal resolution was estimated from the slope of the off-frequency TMC. No significant relationship was found between estimated cochlear compression and MR for either speech or pure tones. NMNH listeners had significantly steeper off-frequency temporal masking recovery slopes than did HI listeners, and a small but significant correlation was observed between poorer temporal resolution and reduced MR for speech. The results suggest either that the effects of hearing impairment on MR are not determined primarily by changes in peripheral compression, or that the TMC does not provide a sufficiently reliable measure of cochlear compression.
    The Journal of the Acoustical Society of America 10/2013; 134(4):2895-2912. DOI:10.1121/1.4818773 · 1.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Noise is one of the most pervasive hazards in the workplace. Despite regulations and preventive measures, noise-induced hearing loss is common. The current reference test is pure-tone air-conduction audiometry (PTA), but this test cannot be used to detect early hearing loss. Objective: In this study, we assess one-day auditory fatigue using both PTA and efferent reflexes (ER) measured using DPOAEs associated with contralateral acoustic stimulation (CAS DPOAEs). Design: The noise exposure history, PTA, and ER detection were performed in seven different companies where the LEX,8h was 85 dB(A). Hearing was tested before and at the end of the working day. Study sample: Forty-six volunteers were selected to carry out this study. Results: After a single working day, a greater impact of noise was measured using ER thresholds than PTA or DPOAEs. ER measurements are objective, easy to perform, and do not require a sound-attenuated booth. Conclusion: Screening workers by periodically measuring ER thresholds using CAS DPOAEs helps detect early changes in hearing status, before the onset of noise-induced hearing loss. These tests can be readily applied as part of a hearing conservation program.
    International Journal of Audiology 05/2014; 53(10):1-8. DOI:10.3109/14992027.2014.913210 · 1.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The temporal masking curve (TMC) method is a behavioral technique for inferring human cochlear compression. The method relies on the assumptions that in the absence of compression, forward-masking recovery is independent of masker level and probe frequency. The present study aimed at testing the validity of these assumptions. Masking recovery was investigated for eight listeners with sensorineural hearing loss carefully selected to have absent or nearly absent distortion product otoacoustic emissions. It is assumed that for these listeners basilar membrane responses are linear, hence that masking recovery is independent of basilar membrane compression. TMCs for probe frequencies of 0.5, 1, 2, 4, and 6 kHz were available for these listeners from a previous study. The dataset included TMCs for masker frequencies equal to the probe frequencies plus reference TMCs measured using a high-frequency probe and a low, off-frequency masker. All of the TMCs were fitted using linear regression, and the resulting slope and intercept values were taken as indicative of masking recovery and masker level, respectively. Results for on-frequency TMCs suggest that forward-masking recovery is generally independent of probe frequency and of masker level and hence that it would be reasonable to use a reference TMC for a high-frequency probe to infer cochlear compression at lower frequencies. Results further show, however, that reference TMCs were sometimes shallower than corresponding on-frequency TMCs for identical probe frequencies, hence that compression could be overestimated in these cases. We discuss possible reasons for this result and the conditions when it might occur. © The Author(s) 2014.
    12/2014; 19. DOI:10.1177/2331216514564253

Full-text (2 Sources)

Available from
Feb 1, 2015