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

Abstract

The relative effectiveness of narrowband and broadband noises in activating the efferent system was assessed by comparing the effect of contralateral stimulation (CS) with such sounds on psychophysical tuning curves (PTCs) determined in simultaneous masking, using signal frequencies of 1000 or 2000 Hz. To check that the CS stimuli used did activate the efferent system, distortion product otoacoustic emissions (DPOAEs) were also measured in the absence and presence of narrowband and broadband CS. The CS had no consistent effect on the masker level at the tips of the PTCs. A broadband pink noise CS consistently reduced the masker level required for threshold on both the low- and high-frequency sides of the PTCs for the 2000-Hz signal frequency. However, there were no consistent effects of the CS for any other case. The broadband pink noise CS had a greater effect in reducing DPOAE levels than the narrowband CS. The results provide psychophysical evidence supporting the idea that the efferent system is activated more effectively by a broadband than by a narrowband CS, at least for a signal frequency of 2000 Hz.

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

“…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. Whilst the previous results have generally been consistent with this expectation, the observed effects have been weak (sometimes non-significant; Quaranta et al 2005), and the pattern of results has been variable across studies (reviewed in Wicher and Moore 2014). Another approach, namely, to measure MOC elicitor effects on psychophysical estimates of cochlear gain and compression, has promised to yield more reliable and consistent results (Krull and Strickland 2008; Jennings et al 2009; Roverud and Strickland 2010; Yasin et al 2014).…”

“…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.…”

“…The elicitor was a broadband noise, because contralateral sounds with broader bandwidths have been shown to be more effective MOC elicitors (Berlin et al 1993; Maison et al 2000; Lisowska et al 2002; Velenovsky and Glattke 2002; Lilaonitkul and Guinan 2009a; Wicher and Moore 2014). Cochlear gain and compression were estimated using the “temporal masking curve” (TMC) method (Nelson et al 2001), which measures forward-masking thresholds for a short sinusoidal signal as a function of the masker-signal gap (the function relating the masking threshold with the masker-signal gap is referred to as TMC; Fig.…”

Medial olivocochlear efferent reflex inhibition of human cochlear nerve responses

“…Psychophysical methods are another approach to quantify MOC effects on total cochlear output (e.g., Kawase et al 2000; Aguilar et al 2013; Wicher & Moore 2014; Strickland 2001, 2004, 2008; Wojtczak et al 2014; Jennings et al 2009; Roverud & Strickland 2010; Yasin et al 2014). Perhaps the most suitable measurements for comparison with our data are those of Yasin et al (2014), although an exact comparison is not possible because we examined the effect of the contralateral MOC reflex on click-evoked CAPs (an objective measure) and they examined the effect of the ipsilateral MOC reflex effects on psychophysical measurements.…”

“…However, each of these reports has issues that prevent it from giving a clear picture of MOC effects on cochlear neural output in awake, alert, normal-hearing humans. Indirect measurements of MOC inhibition have been made psychophysically (e.g., Kawase et al 2000; Aguilar et al 2013; Wicher & Moore 2014; Strickland 2001, 2004, 2008; Wojtczak et al 2014; Jennings et al 2009; Roverud & Strickland 2010; Yasin et al 2014). But, psychophysical measurements are confounded by the possibility that the MOC reflex, the sound used to elicit MOC reflex, or the attention required for the psychophysical measurements, may change signal processing in the brain as well as in the cochlea (Keefe et al 2009; Wittekindt et al 2014).…”