Behavioral and physiological correlates of temporal pitch perception in electric and acoustic hearing

Abstract

In the "4-6" condition of experiment 1, normal-hearing (NH) listeners compared the pitch of a bandpass-filtered pulse train, whose inter-pulse intervals (IPIs) alternated between 4 and 6 ms, to that of isochronous pulse trains. Consistent with previous results obtained at a lower signal level, the pitch of the 4-6 stimulus corresponded to that of an isochronous pulse train having a period of 5.7 ms -longer than the mean IPI of 5 ms. In other conditions the IPI alternated between 3.5-5.5 ms and 4.5-6.5 ms. Experiment 2 was similar but presented electric pulse trains to one channel of a CI. In both cases, as overall IPI increased, the pitch of the alternating-interval stimulus approached that of an isochronous train having a period equal to the mean IPI. Experiment 3 measured compound action potentials (CAPs) to alternating-interval stimuli in guinea pigs and in NH listeners. The CAPs to pulses occurring after 4-ms intervals were smaller than responses to pulses occurring after 6-ms intervals, resulting in a modulated pattern that was independent of overall level. The results are compared to the predictions of a simple model incorporating auditory-nerve (AN) refractoriness, and where pitch is estimated from 1 st -order intervals in the AN response.

Understanding Pitch Perception as a Hierarchical Process with Top-Down Modulation

“…The stimuli in question are high-pass-filtered click trains where the interval between successive clicks varies. Previously we showed that the cascade autocorrelation model with fixed integration times [13] predicted the pitch percept elicited by a range of click train stimuli, which had proved problematic for conventional autocorrelation models [49,50,[60][61][62][63]. Here, we test whether the current model (which generalizes the model reported in [13] by including variable integration times) retains this ability.…”

“…They also added a pink noise to avoid audible distortion products. Carlyon et al [50] demonstrated that the combined auditory nerve responses, measured as compound action potentials (CAPs), were stronger for the largest inter-click interval (6 ms) than for the shorter interval (4 ms). Therefore, they suggested that a population of more central neurons, which respond only when their inputs exceed a fixed threshold value, would respond preferentially to the longer intervals, thereby explaining listeners' preference for matching a pitch close to 6 ms. Figure 8C shows that the predicted pitch of the model (red highlight) varies almost randomly for approximately 80 ms and then progressively stabilizes at a lag in the region of 5.5-6 ms (see horizontal arrow in Figure 8C).…”

“…Figure 2B showed that the model uses very short integration times for pitch information when a change in pitch occurs. However, it is possible to construct a class of stimuli, in which the periodicities change continually over very short time scales but which nevertheless elicit a single pitch [49,50], suggesting that pitch information is integrated across these rapid changes in periodicity. The stimuli in question are high-pass-filtered click trains where the interval between successive clicks varies.…”

Modulation Frequency Discrimination with Modulated and Unmodulated Interference in Normal Hearing and in Cochlear-Implant Users

“…Carlyon and colleagues have shown that CI users are often sensitive to changes in pulse rates in ways that resemble the sensitivity shown by normal-hearing (NH) listeners when presented with acoustic pulse trains that are high-pass filtered to remove potentially resolved spectral components (e.g., Carlyon et al 2002Carlyon et al , 2008. Also, NH listeners have been shown to make use of temporal-envelope pitch cues when listening to speech against a background of a competing talker (Oxenham and Simonson 2009), suggesting that such cues might, in principle, be available to CI users.…”

Combined neural and behavioural measures of temporal pitch perception in cochlear implant users

“…Further evidence comes from experiments with acoustic pulse trains filtered into high frequency regions. These stimuli present normal-hearing (NH) listeners with purely temporal rate information, in the absence of any place-of-excitation cues, and have been successfully used as simulations of electric pulse trains presented to CIs (McKay and Carlyon, 1999;van Wieringen et al, 2003;Carlyon et al, 2008a;Carlyon et al, 2008b;Carlyon et al, 2011). NH listeners can detect differences in pulse rate up to about 700 pps Macherey and Carlyon, 2014), which is higher than the 300 pps observed for the majority of CI users, and similar to that of the best CI users, consistent with most patients having a limitation arising from damage to, or degradation of, the peripheral auditory system.…”