The Effect of Contralateral Signal on Distortion Product Otoacoustic Emissions and Psychophysical Tuning Curves at 1 and 2 kHz

Abstract

The main aim of this work was to determine the inuence of contralateral stimulation (CS) on the psychophysical tuning curves (PTCs) and distortion product otoacoustic emissions (DPOAEs). PTCs and DPOAEs were measured in two modes: in the presence or absence of CS. The contralateral signal was a wideband noise (bandwidth 0.210 kHz) at a level of 50 dB sound pressure level (SPL). The primary tones (F1 and F2) were presented at levels of L1 = 60 dB SPL, and L2 = 50 dB SPL. The signal frequency used in the measurements of the PTC was 1 kHz or 2 kHz. For both PTC signal frequencies the CS signicantly reduces the sharpness of the PTCs. The average change in level of DPOAE under the inuence of CS throughout the whole range of frequencies takes an eect of suppression. The CS has a signicant eect on decreasing the value of the quality factor (Q10Roex) of PTCs (F (1, 9) = 19.36, p = 0.002). The CS caused a decrease in the level of DPOAE in 88% of cases. The maximum suppression of the DPOAE level occurs for the F2 frequency from 1 kHz to 2 kHz.

Effect of broadband and narrowband contralateral noise on psychophysical tuning curves and otoacoustic emissions

“…Also, the effect of the middle-ear reflex is very weak for frequencies above 1500 Hz (Liberman and Guinan, 1998), while the CS had a clear effect for frequencies above 1500 Hz. Finally, similar but slightly smaller values of DL DP were obtained by Wicher (2013) for a broadband CS with a level of 50 dB SPL, a level that would be too low to activate the middle-ear reflex. Therefore it seems likely that the effect of the CS was mainly mediated by activation of the efferent system.…”

“…In the present study, the CS was either a NBN centered at the signal frequency, as used by Quaranta et al (2005) and by Vinay and Moore (2008), or a broadband noise, as used by Kawase et al (2000), Wicher (2013), and Aguilar et al (2013). This allowed a direct comparison of the effects of narrowband and broadband CS.…”

“…A forced-choice method was used to estimate the masker level required for threshold. This is more time-consuming than the adjustment method used by Vinay and Moore (2008) or the "fast" method used by Wicher (2013), but the results are not affected by the criterion of the subject and are more reliable. Francis and Guinan (2010) pointed out some problems in interpreting the effects of CS on PTCs.…”

Effect of Contralateral Medial Olivocochlear Feedback on Perceptual Estimates of Cochlear Gain and Compression

“…A number of previous studies have measured contralateral MOC elicitor effects on psychophysical (frequency) tuning curves (PTCs; Kawase et al 2000; Quaranta et al 2005; Vinay and Moore 2008; Aguilar et al 2013; Wicher 2013; Wicher and Moore 2014). PTCs measure the level of a variable-frequency masker needed to just mask a low-level, fixed-frequency signal.…”

“…However, overshoot is not a suitable approach for measuring contralateral MOC function, because (i) MOC involvement in overshoot has been questioned (Bacon and Moore 1987; Scharf et al 2008; Fletcher et al 2015) and (ii) contralateral precursor effects have been hard to find (Bacon and Healy 2000; Bacon and Liu 2000). Several previous studies have measured contralateral MOC elicitor effects on psychophysical measures of cochlear frequency selectivity (Kawase et al 2000; Quaranta et al 2005; Vinay and Moore 2008; Aguilar et al 2013; Wicher 2013; Wicher and Moore 2014). The active cochlear amplifier enhances cochlear frequency selectivity (Robles and Ruggero 2001), and so, MOC-induced reduction in amplifier gain should be associated with a decrease in frequency selectivity.…”