Peripheral auditory lateralization assessment using TEOAEs

https://doi.org/10.1016/S0378-5955(98)00062-8Get rights and content

Abstract

Previous studies indicate a left-right asymmetry in the function of peripheral auditory system. Contralateral acoustic suppression of TEOAEs (transient evoked otoacoustic emissions) enables assessment of medial olivocochlear efferent system functioning, and has demonstrated that this system is more effective in the right than in the left ear. Moreover, TEOAE amplitudes are lower in the left than in the right ear. The aim of the present experiment was to verify firstly the absence of a relationship between medial efferent system asymmetry and TEOAE amplitude asymmetry, and secondly to study TEOAE input/output function slopes. There was no link between the asymmetries in TEOAE amplitude and in the medial efferent system functioning. Further, as previously shown, the medial olivocochlear system increased the TEOAE input/output function slopes. These TEOAE input/output function slopes seem to be consistent factors in peripheral asymmetry since the slope is lower in the right than in the left ear. Moreover, the lower the TEOAE amplitudes, the greater the TEOAE slopes. The slope asymmetry of the two ears could correspond to earlier saturation or a lower augmentation ability of the TEOAE response in the right ear, where the TEOAE amplitude is higher. This asymmetry in growth slopes reinforces the notion of peripheral auditory lateralization.

Introduction

The asymmetrical anatomy of the human brain is well known (Geschwind and Levitsky, 1968). The auditory lateralization in speech processing (Kimura, 1961) probably is not dependent on a single mechanism (Jäncke et al., 1992), but involves both cognitive and perceptual components. For example, a perceptual auditory asymmetry has been demonstrated (Brown and Nicholls, 1997) in an experiment carried out with 24 normal adults whose reaction times, response biases and response errors revealed a right ear (i.e. left hemisphere) advantage in gap detection. Absolute auditory thresholds also seem to be better, i.e. lower, in the right ear (see McFadden, 1993), especially at 3–4 kHz (Eagles et al., 1963). Recently, further evidence for the existence of a left/right asymmetry in the functioning of the human peripheral auditory system has been provided by the demonstration of stronger auditory efferent activity in the right than in the left ear (Khalfa and Collet, 1996).

In this study, following a method defined by Collet et al. (1990), medial olivocochlear (MOC) activity was assessed through the suppression of transient evoked otoacoustic emission (TEOAE) amplitude elicited by contralateral acoustic stimulation (CAS). To assess this peripheral suppression, an equivalent attenuation (EA) calculation procedure has been used (Collet et al., 1992; Chéry-Croze et al., 1994). EA corresponds to the decrease in the ipsilateral stimulus intensity (eliciting TEOAEs) which would be necessary to obtain, in the absence of the contralateral broad-band noise (BBN) stimulus (eliciting TEOAE suppression), the same response than with CAS, i.e. activating the MOC system. Five different EAs calculated with five different ipsilateral stimulus intensities were averaged to obtain a more representative EA. Besides the interaural asymmetry in olivocochlear system functioning, an asymmetry in the cochlear functioning itself is indicated by the finding of larger TEOAE amplitudes in the right than in the left ear (Khalfa et al., 1997).

The first aim of this study was to test whether these two features of peripheral auditory lateralization were linked. Then, in order to complete the study of interaural TEOAE asymmetries, a second aim was to test for the existence of an interaural asymmetry in TEOAE growth function slopes. It has been shown in a previous study (Veuillet et al., 1991) that the CAS activating MOC system increases TEOAE input/output (i/o) function slopes, i.e. the slopes of ipsilateral stimulus intensities as a function of TEOAE amplitude, corresponding to regression lines computed from the five experimental points compared to the slopes obtained without CAS. These slopes represent physiological mechanisms reflecting TEOAE dynamics and show to a certain extent the degree of TEOAE amplitude enhancement when stimulus intensity is increased. The effect of CAS on the TEOAE slopes has been studied in our present large population to compare with previous results. MOC system functional asymmetry can act on either ear of each subject, with varying strength and also vary according to ipsilateral acoustic stimulation intensity. The influence of the MOC system on the increase in TEOAE i/o function slope was therefore studied in both ears, considering that this system tends to be more effective in right ears.

Section snippets

Subjects

Sixty-seven normal-hearing subjects (<20 dB loss between 250 and 8000 Hz per octave on pure tone audiogram), aged from 18 to 31 years (mean=22.735 years; S.D.=2.773) were included in this study. Their hand preference laterality quotient was calculated using the Edinburgh Handedness Inventory (Oldfield, 1971). Only right-handed subjects (with positive handedness laterality quotient) as assessed by this test were included in this experiment, because hemispheric specialization is less marked in

Relationship between EA and TEOAE amplitudes

No significant correlation was found between EA and TEOAE amplitude in the right ear (Fig. 3), or in the left ear (Fig. 4). Whatever the ipsilateral stimulation intensity used (80, 71, 67, 65, 63, 59±3 dB peSPL) to evoke OAEs, no significant correlation was observed between TEOAE amplitude and EA.

Relationship between EA asymmetry and TEOAE amplitude asymmetry

Right ear EA minus left ear EA was plotted against right ear minus left ear TEOAE amplitude for 0 dB gain, in Fig. 5. No correlation between the two asymmetries was found, whichever the ipsilateral

Two independent signs of peripheral auditory lateralization

It has been established by previous studies that EA is lower in the right than in the left ear, and also that the medial efferent system is more effective in the right ear (Khalfa and Collet, 1996). Moreover, TEOAE amplitude reflecting active cochlear mechanisms has been found to be greater in the right ear (Khalfa et al., 1997).

EA does not seem to be linked to TEOAE amplitude in either ear. Indeed, in both the right (Fig. 3) and the left ear (Fig. 4), the absence of correlation shows that

Conclusion

The results of the present study indicate that the asymmetry of the MOC system reflected in the difference between right and left ear EA is not the result of the asymmetry of the TEOAE amplitudes involved in the EA calculation. These results provide further support to the notion that auditory efferent activity is asymmetrical between the two ears and attenuates right ear TEOAE amplitude more effectively than left ear TEOAE levels. However, the changes in TEOAE i/o function slope observed upon

References (21)

There are more references available in the full text version of this article.

Cited by (43)

  • Otoacoustic emission suppression in children diagnosed with central auditory processing disorder and speech in noise perception deficits

    2018, International Journal of Pediatric Otorhinolaryngology
    Citation Excerpt :

    The right ear advantage of the auditory system for right-handed listeners is well documented for a range of auditory tests including the audiogram [50], auditory-evoked potentials [51], and contralateral suppression of TOAEs, both in adults and children [18,52,53]. The suppression effect in particular has being proposed as a marker of peripheral auditory lateralization that is independent of TOAE strength [54]. The finding of a persistent right ear advantage in our group with abnormal speech recognition performance as well as the one with normal SinB shows normal lateralization in this pediatric group who experience communication difficulties due to abnormal central auditory processing.

  • Function and plasticity of the medial olivocochlear system in musicians: A review

    2014, Hearing Research
    Citation Excerpt :

    However, it is worth noting that in the works of Perrot et al. (1999) and Brashears et al. (2003), although baseline EOAE amplitudes for both ears tended to be larger (albeit not statistically significantly) in professional musicians than in non-musicians, no correlation between efferent suppression and baseline amplitude of EOAEs was found (Table 1-D and 1-E). This outcome is in line with earlier findings in non-musician subjects, which showed that the amplitude of EOAEs and the magnitude of contralateral OAE suppression were two independent markers of peripheral auditory functioning, the former reflecting ACMs whereas the latter presumably reflects MOC activity (Hood et al., 1996; Khalfa et al., 1998a). The first hypothesis involves a strengthening of cortico-olivocochlear modulation of the MOCS with musical practice.

  • Study on suppression of otoacoustic emissions: lateral domain

    2011, Brazilian Journal of Otorhinolaryngology
    Citation Excerpt :

    Table 5 presents the double factor analysis of variance without repetitions- alpha (significance level) equaling 0.05 (5%) - for the degree of reduction, comparing the right and left ears, revealed that there was no statistically significant difference between both ears. A comparison of our findings (presented in Annex 1 and treated statistically - Tables 3, 4 and 5) with studies by Khalfa & Collet7, and Khalfa et al.8, who applied similar methods, shows that the findings did not correlate. In our study, there was no statistically significant difference for the presence of the suppression/reduction effect of evoked otoacoustic emissions and its amplitude relative to right/left dominance in normal hearing adult subjects.

  • Attention and the right-ear advantage: What is the connection?

    2011, Brain and Cognition
    Citation Excerpt :

    Some evidence indicates that auditory sensitivity is greater for the right ear than the left ear (Kannan & Lipscomb, 1974; McFadden, 1993), and this difference between ears seems to be more prominent in males than in females (Chung, Mason, Gannon, & Wilson, 1983). Spontaneous otoacoustic emissions (OAEs) in adults have been reported to occur more frequently on the right side than on the left side (Bilger, Matthies, Hammel, & Demorest, 1990), and the amplitude of transient evoked OAEs is greater on the right side (Khalfa, Micheyl, Veuillet, & Collet, 1998). Sininger and Cone-Wesson (2004; 2006) have shown that, in neonates, the OAEs elicited by rapid clicks are larger for the right ear than for the left, and that the click-induced brainstem response for rapid stimuli of short duration is reliably larger in amplitude and shorter in latency on the right side than on the left side.

  • Pure-tone auditory thresholds are decreased in depressed people with post-traumatic stress disorder

    2010, Journal of Affective Disorders
    Citation Excerpt :

    For both ears, AC was assessed prior to BC. Tonal audiometry was performed to measure pure-tone thresholds, i.e., minimum detectable level of sounds in the absence of any external sounds (Goldstein and Shulman, 1996; Khalfa et al., 2004). Sound levels were expressed in dB HL at 25 frequencies from the highest to the lowest frequencies in the following decreasing gradient of pitch order: 8, 6, 5, 4.5, 4, 3.5, 3, 2.75, 2.5, 2.25, 2, 1.87, 1.75, 1.625, 1.5, 1.375, 1.25, 1.125, 1, 0.875, 0.75, 0.625, 0.5, 0.25 and 0.125 kHz.

View all citing articles on Scopus
View full text