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. 2009 Oct;30(5):489-93.
doi: 10.1097/AUD.0b013e3181ab2b87.

Achieving electric-acoustic benefit with a modulated tone

Christopher A Brown  1 , Sid P Bacon
Affiliations

Achieving electric-acoustic benefit with a modulated tone

Christopher A Brown et al. Ear Hear. 2009 Oct.

Abstract

Objective: When either real or simulated electric stimulation from a cochlear implant (CI) is combined with low-frequency acoustic stimulation (electric-acoustic stimulation [EAS]), speech intelligibility in noise can improve dramatically. We recently showed that a similar benefit to intelligibility can be observed in simulation when the low-frequency acoustic stimulation (low-pass target speech) is replaced with a tone that is modulated both in frequency with the fundamental frequency (F0) of the target talker and in amplitude with the amplitude envelope of the low-pass target speech (). The goal of the current experiment was to examine the benefit of the modulated tone to intelligibility in CI patients.

Design: Eight CI users who had some residual acoustic hearing either in the implanted ear, the unimplanted ear, or both ears participated in this study. Target speech was combined with either multitalker babble or a single competing talker and presented to the implant. Stimulation to the acoustic region consisted of no signal, target speech, or a tone that was modulated in frequency to track the changes in the target talker's F0 and in amplitude to track the amplitude envelope of target speech low-pass filtered at 500 Hz.

Results: All patients showed improvements in intelligibility over electric-only stimulation when either the tone or target speech was presented acoustically. The average improvement in intelligibility was 46 percentage points due to the tone and 55 percentage points due to target speech.

Conclusions: The results demonstrate that a tone carrying F0 and amplitude envelope cues of target speech can provide significant benefit to CI users and may lead to new technologies that could offer EAS benefit to many patients who would not benefit from current EAS approaches.

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Figures

Fig 1
Fig 1
A, Unaided audiometric thresholds for each ear tested of each subject. Each shade of gray and symbol represents a unique patient. Dashed lines represent performance when the ear ipsilateral to the implanted was tested; solid lines represent performance when the ear contralateral to the implanted was tested. Note that two patients (6 and 8) had some residual hearing in both their implanted and unimplanted ears. B, Mean percent correct scores. Plot shades, symbols, and lines are consistent with those from A. The bold plot with filled circles represents group mean performance. The processing conditions, depicted along the x axis, were electric-only stimulation (E), electric plus acoustically delivered target speech (EASSp), and electric plus acoustically delivered tone (EAST). We have connected each plot with lines for clarity even though the processing variable is not continuous.
See this image and copyright information in PMC

References

    1. Auditec. Auditory Tests (Revised) (Compact Disc) St. Louis: Auditec; 1997.
    1. Brown CA, Bacon SP. Learning effects in simulated electric-acoustic hearing. 31st Midwinter Meeting of the Association for Research in Otolaryngology; Phoenix, AZ. 2008.
    1. Brown CA, Bacon SP. Low-frequency speech cues and simulated electric-acoustic hearing. J Acoust Soc Am. 2009;125:1658–1665. - PMC - PubMed
    1. Chang JE, Bai JY, Zeng F. Unintelligible low-frequency sound enhances simulated cochlear-implant speech recognition in noise. IEEE Trans Biomed Eng. 2006;53:2598–2601. - PubMed
    1. Davis H, Silverman SR. Hearing and Deafness. New York: Holt, Rhinehart, and Winston; 1978.

REFERENCE NOTES

    1. Boothroyd A, Hanin L, Hnath T. Internal Report RCI 10. New York: Speech & Hearing Sciences Research Center, City University of New York; 1985. A Sentence Test of Speech Perception: Reliability, Set Equivalence, and Short Term Learning.
    1. Scherrer N, Brown C, Bacon S. Effect of Fundamental Frequency on Intelligibility in Simulated Electric-Acoustic Listening. Scottsdale, AZ: American Auditory Society; 2007.

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