Effects of the Conditioning Click on Click-evoked Otoacoustic Emission

Abstract

The effects of the preceding (conditioning) click on the evoked otoacoustic emission (EOAE) to the following (test) click were investigated in normally hearing adults. To overcome distortions due to superimposition of the test EOAE on the EOAE to the conditioning click, a special stimulation and response subtraction procedure was utilized. The conditioning stimulus was found to suppress the test EOAE. The suppression lessened with a decrease in the conditioning stimulus level and an increase in the time interval between the conditioning and the test stimuli. Nevertheless, the influence was traced even with the level of the conditioning stimulus as low as 5 dB SL, and lasted for the interval between the conditioning and the test stimuli, as long as 7.5 ms. An attempt at theoretical comprehension of the obtained results is made and their usefulness in differentiation of EOAEs from acoustic reflections is proposed.

Temporal suppression and augmentation of click-evoked otoacoustic emissions

“…3) is quantitatively comparable to the suppression reported by Hine and Thornton (2002), who found maximal suppression of 4-5 dB at an ICI of 1 ms for stimulus-levels of 65 dB peSPL and time-frames between 7 and 17 ms. Qualitatively, the data of Tavartkiladze et al (1994) and Kevanishvili et al (1996) showed similar trends of suppression as a function of ICI. Augmentation of the CEOAE (i.e., S < 0) was observed using method 1 for ICIs between 5 and 8 ms and for time-frames between 15 and 21 ms (upper-left panel in Fig.…”

“…This is in agreement with Tavartkiladze et al (1994), who reported augmentation of the CEOAE for an ICI of 7 ms. However, Kevanishvili et al (1996) and Hine and Thornton (2002) have not observed augmentation for the short-latency CEOAE in the double-click paradigm.…”

“…This method was introduced by Tavartkiladze et al (1994), and adopted by Kevanishvili et al (1996) and Hine and Thornton (2002) in further studies. For each ICI, two responses were measured: (i) the double-click response consisting of a suppressor-click (S-click) and a test-click (T-click), and (ii) the single-click or unsuppressed response with the click positioned at the S-click of the double-click stimulus.…”

“…A discrepancy exists in the experimental studies about the observation of augmentation (Kemp and Chum, 1980a;Tavartkiladze et al, 1994;Lina-Granade and Collet, 1995;Kevanishvili et al, 1996;Kapadia and Lutman, 2000b;Hine and Thornton, 2002), which is defined as the increase in CEOAE-level when presenting a suppressor-click close in time (e.g. 0-8 ms) before a test-click.…”

“…This compressive CEOAE level-curve is an important feature of the underlying CEOAE generator mechanisms, and is very similar to the compression observed in the basilar membrane velocity for medium to intense sound inputs (Robles et al, 1986). Both basilar membrane-and CEOAE-compression are thought to have similar origins in the cochlear amplifier (Gold, 1948;Davis, 1983) and have been investigated in the past by means of suppression in CEOAEs (Kemp and Chum, 1980a;Tavartkiladze et al, 1994;Lina-Granade and Collet, 1995;Kevanishvili et al, 1996;Kapadia and Lutman, 2000b;Hine and Thornton, 2002). Suppression is defined as the amplitude reduction that can be observed in the CEOAE when a so-called suppressor-click is presented close in time (e.g.…”