Vocoder Simulations of Highly Focused Cochlear Stimulation With Limited Dynamic Range and Discriminable Steps

Stafford, Ryan; Stafford, James W.; Wells, Jonathon; Loizou, Philipos C.; Keller, Matthew D.

doi:10.1097/aud.0b013e3182a768e8

Cited by 16 publications

(19 citation statements)

References 2 publications

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“…We used 15 channels for two reasons. First, extreme filter slopes are likely to be most (or even only) effective for higher numbers of channels (up to certain limits), because channels are more difficult to segregate in a denser configuration (Stafford et al, 2014). Second, the studies by Litvak et al (2007) and van de Velde et al (2015) also used 15 channels, allowing a relatively straightforward comparison between their results and ours.…”

Section: Introductionmentioning

confidence: 76%

“…The selection of the exact range of filter slopes to be tested was based on pilot data, starting from findings in the literature that for higher channel numbers only the more extreme filter slopes are likely to show an effect since they are spaced closely together (Bingabr et al, 2008;Stafford et al, 2014). The pilot study explored several filter slopes to identify the range between chance and ceiling performance on a simple two-alternative forced choice (2AFC) prosody discrimination task, similar to the main experiment of this study.…”

Section: Introductionmentioning

confidence: 99%

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The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes

Velde

Schiller

Heuven

et al. 2017

The Journal of the Acoustical Society of America

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This study aimed to find the optimal filter slope for cochlear implant simulations (vocoding) by testing the effect of a wide range of slopes on the discrimination of emotional and linguistic (focus) prosody, with varying availability of F0 and duration cues. Forty normally hearing participants judged if (non-)vocoded sentences were pronounced with happy or sad emotion, or with adjectival or nominal focus. Sentences were recorded as natural stimuli and manipulated to contain only emotion- or focus-relevant segmental duration or F0 information or both, and then noise-vocoded with 5, 20, 80, 120, and 160 dB/octave filter slopes. Performance increased with steeper slopes, but only up to 120 dB/octave, with bigger effects for emotion than for focus perception. For emotion, results with both cues most closely resembled results with F0, while for focus results with both cues most closely resembled those with duration, showing emotion perception relies primarily on F0, and focus perception on duration. This suggests that filter slopes affect focus perception less than emotion perception because for emotion, F0 is both more informative and more affected. The performance increase until extreme filter slope values suggests that much performance improvement in prosody perception is still to be gained for CI users.

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Section: Introductionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes

Velde

Schiller

Heuven

et al. 2017

The Journal of the Acoustical Society of America

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“…It is worth noting that the filters which led to a plateau of performance in the present study (MP and BP þ 1) had bandwidths in between the medium and broad conditions of Bingabr et al, and that they led to a similar plateau. Recently, several vocoder studies have also used synthesis filter shapes similar to those of Bingabr et al in order to simulate the spread of excitation produced by a CI (Churchill et al, 2014;Stafford et al, 2014). Strydom and Hanekom (2011a) followed a different approach.…”

Section: Discussionmentioning

confidence: 98%

Simulating the dual-peak excitation pattern produced by bipolar stimulation of a cochlear implant: Effects on speech intelligibility

Mesnildrey

Macherey

2015

Hearing Research

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“…There was no attempt in this study to simulate pulsatile stimulation, staggered channel selection, and the nearly ubiquitous upward shifting of all frequency energy (c.f., Başkent & Shannon 2005). We did also not simulate properties of electrical loudness growth (Chatterjee, 1999), limited dynamic range (Stafford et al, 2013), place-frequency nonmonotonicity (Donaldson & Nelson 2000), inconsistent electrode– neuron interface, and atrophy of cells in the cochlea and spiral ganglion (Nadol 1997). While these factors can be built into a vocoder, they are more idiosyncratic to individual listeners rather than the CI listener population in general, and were thus not tested in the present study.…”

Section: Discussionmentioning

confidence: 99%

The Impact of Auditory Spectral Resolution on Listening Effort Revealed by Pupil Dilation

Winn

Edwards

Litovsky³

2015

Ear &Amp; Hearing

237

308

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Objectives This study measured the impact of auditory spectral resolution on listening effort. Systematic degradation in spectral resolution was hypothesized to elicit corresponding systematic increases in pupil dilation, consistent with the notion of pupil dilation as a marker of cognitive load. Design Spectral resolution of sentences was varied with 2 different vocoders: (1) a noise channel vocoder with a variable number of spectral channels; and (2) a vocoder designed to simulate front-end processing of a cochlear implant, including peak-picking channel selection with variable synthesis filter slopes to simulate spread of neural excitation. Pupil dilation was measured after subject-specific luminance adjustment and trial-specific baseline measures. Mixed-effects growth curve analysis was used to model pupillary responses over time. Results For both types of vocoder, pupil dilation grew with each successive degradation in spectral resolution. Within each condition, pupillary responses were not related to intelligibility scores, and the effect of spectral resolution on pupil dilation persisted even when only analyzing trials in which responses were 100% correct. Conclusions Intelligibility scores alone were not sufficient to quantify the effort required to understand speech with poor resolution. Degraded spectral resolution results in increased effort required to understand speech, even when intelligibility is at 100%. Pupillary responses were a sensitive and highly granular measurement to reveal changes in listening effort. Pupillary responses might potentially reveal the benefits of aural prostheses that are not captured by speech intelligibility performance alone, as well as the disadvantages that are overcome by increased listening effort.

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Vocoder Simulations of Highly Focused Cochlear Stimulation With Limited Dynamic Range and Discriminable Steps

Abstract: Highly focused stimulation-tripolar electrical and infrared neural stimulation-has potential for increased performance in noise compared with monopolar stimulation, but much work remains to bear this potential out and to take full advantage of each modality's strengths.

Cited by 16 publications

References 2 publications

The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes

The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes

Simulating the dual-peak excitation pattern produced by bipolar stimulation of a cochlear implant: Effects on speech intelligibility

The Impact of Auditory Spectral Resolution on Listening Effort Revealed by Pupil Dilation

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