Die Pegelzunahme von Distorsionsproduktemissionen des Menschen durch kontralaterale Beschallung niedriger Intensität

Abstract

Distortion product otoacoustic emissions (DPOAEs) are probably based on the motile properties of the cochlear outer hair cells (OHCs), which are richly innervated by medial olivo-cochlear efferent nerves (MOCs). DPOAEs provide a stimulating model for functional exploration of the efferent system. The influences of contralateral acoustic stimulation were studied on the amplitude of ipsilateral DPOAEs at the frequency 2f1-f2. Fifteen ears of adults with normal hearing (7 women, 8 men, mean age; 23.1 +/- 4.2 years) were examined. Sound stimulation consisted of exposure to 6 successive series of contralateral pure tones at frequencies between 0.5 and 4.0 kHz and low intensities of 30 dB HL. DP grams were registered with f2 ranging from 708 to 6165 Hz. Contralateral pure tones in the frequency range above 750 Hz and with intensities of 30 dB HL increased the ipsilaterally registered DPOAE amplitudes. The results showed that this increase was frequency specific, at least for frequencies at 1 and 2 kHz. The frequency specificity was especially marked when ipsilateral f2 was near 1 kHz. Contralateral frequencies of 3 and 4 kHz induced a significant, increasing effect, including ipsilateral frequencies around f2 = 3 kHz (or 4 kHz) and also lower frequencies around f2 = 1 kHz. Our results support the concept that the observed increase in DPOAE amplitudes is mediated by the medial olivo-cochlear efferent system. The rule of OHCs as a cochlear amplifier in the presence of contralateral low-intensity sound stimulation is discussed.

Influence of Contralateral Stimulation by Two-tone Complexes, Narrow-band and Broad-band Noise Signals on the 2f 1 -f 2 Distortion Product Otoacoustic Emission Levels in Humans

“…Similar ndings have previously been reported in both humans (12,17,18) and animals (22). Thus, the efferent bers do not necessarily have to have a suppressive in uence on OHC motility.…”

“…Moreover, some studies in humans have also demonstrated an enhancement of SOAE (8), DPOAE (12,17) and TEOAE (18) amplitudes in the presence of CS. Nieschalk et al (17) observed that contralateral pure tones at frequencies \750 Hz and with intensities of 30 dB HL increased DPOAE amplitudes. The mechanisms of both the enhancement and suppression effects remain unclear.…”

“…Broad-band noise (BBN) appears to be the most effective stimulus (11,15). Moreover, some studies in humans have also demonstrated an enhancement of SOAE (8), DPOAE (12,17) and TEOAE (18) amplitudes in the presence of CS. Nieschalk et al (17) observed that contralateral pure tones at frequencies \750 Hz and with intensities of 30 dB HL increased DPOAE amplitudes.…”

Olivocochlear reflex effect on human distortion product otoacoustic emissions is largest at frequencies with distinct fine structure dips

“…In 12 of these, stimulus frequency was varied whereas primary tone levels were held constant (Bassim et al, 2003;James et al, 2002;Kim et al, 2002;Lisowska et al, 2002;Di Girolamo et al, 2001;Sasaki et al, 2000;Timpe-Syverson and Decker, 1999;Williams and Brown, 1995;Moulin et al, 1992;Nieschalk et al, 1997;Chery-Croze et al, 1993;Moulin and Carrier, 1998). Reported suppression effects ranged from <1 to a few dB.…”

Impact of occupational noise on pure-tone threshold and distortion product otoacoustic emissions after one workday

“…However, the term DPOAE suppression is misleading because it was found that not only suppression but also enhancement of the DPOAE amplitude occurs (e.g. Nieschalk et al, 1997;Kujawa and Liberman, 2001). Therefore, in the following this technique is referred to as CAS DPOAE.…”