The Advanced Combination Encoder (ACE) signal processing strategy is used in the majority of cochlear implant (CI) sound processors manufactured by Cochlear Corporation. This “n-of-m” strategy selects “n” out of “m” available frequency channels with the highest spectral energy in each stimulation cycle. It is hypothesized that at low signal-to-noise ratio (SNR) conditions, noise–dominant frequency channels are susceptible for selection, neglecting channels containing target speech cues. In order to improve speech segregation in noise, explicit encoding of formant frequency locations within the standard channel selection framework of ACE is suggested. Two strategies using the direct formant estimation algorithms are developed within this study, FACE (formant-ACE) and VFACE (voiced-activated-formant-ACE). Speech intelligibility from eight CI users is compared across 11 acoustic conditions, including mixtures of noise and reverberation at multiple SNRs. Significant intelligibility gains were observed with VFACE over ACE in 5 dB babble noise; however, results with FACE/VFACE in all other conditions were comparable to standard ACE. An increased selection of channels associated with the second formant frequency is observed for FACE and VFACE. Both proposed methods may serve as potential supplementary channel selection techniques for the ACE sound processing strategy for cochlear implants.
References
1.
Ali
, H.
, Ammula
, S.
, and Hansen
, J. H. L.
(2017
). “Subjective evaluation with UT–Dallas research interface for cochlear implant users
,” in Proceedings of the Conference on Implantable Auditory Prostheses (CIAP 2017)
, July 16–21
, Lake Tahoe, CA
, p. 211
.2.
Ali
, H.
, Hong
, F.
, Hansen
, J. H. L.
, and Tobey
, E.
(2014
). “Improving channel selection of sound coding algorithms in cochlear implants
,” in Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP'14)
, May 4–9
, Florence, Italy
, pp. 905
–909
.3.
Ali
, H.
, Hong
, F.
, Wang
, J.
, and Hansen
, J. H. L.
(2016
). “Mobile research interface for cochlear implants
,” in Proceedings of the International Conference on Cochlear Implants (CI2016)
, May 11–14
, Toronto, Canada
, pp. 27
.4.
Alku
, P.
, Pohjalainen
, J.
, Laukkanen
, A. M.
, and Story
, B. H.
(2013
). “Formant frequency estimation of high-pitched vowels using weighted linear prediction
,” J. Acoust. Soc. Am.
134
, 1295
–1313
.5.
Assmann
, P. F.
, and Summerfield
, Q.
(2004
). “The perception of speech under adverse conditions
,” in Handbook of Audiology Research
, edited by W.
Greenberg
, W. A.
Ainsworth
, A. N.
Popper
, and R. R.
Fay
(Springer
, New York
), pp. 231
–308
.6.
Blamey
, P. J.
, Dowell
, R. C.
, Clark
, G. M.
, and Seligman
, P. M.
(1987
). “Acoustic parameters measured by a formant-estimating speech processor for a multiple-channel cochlear implant
,” J. Acoust. Soc. Am.
82
, 38
–47
.7.
Blamey
, P. J.
, Dowell
, R. C.
, Tong
, Y. C.
, Brown
, A. M.
, Luscombe
, S. M.
, and Clark
, G. M.
(1984
). “Speech processing studies using an acoustic model of a multiple-channel cochlear implant
,” J. Acoust. Soc. Am.
76
, 104
–110
.8.
Brown
, C. A.
, and Bacon
, S. P.
(2011
). “Fundamental frequency and speech intelligibility in background noise
,” Hear. Res.
266
, 52
–59
.9.
Chen
, B.
, and Loizou
, P. C.
(2004
). “Formant frequency estimation in noise
,” in Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP'04)
, May 17–21
, Montreal, Canada
, pp. I–581
–584
.10.
Choi
, C. T. M.
, and Lee
, Y. H.
(2012
). “A review of stimulating strategies for cochlear implants
,” in Cochlear Implant Research Updates
, edited by C.
Umat
, and R. A.
Tange
(InTech Europe
, Rijeka, Croatia
), pp. 77
–90
.11.
Clay
, K. M. S.
, and Brown
, C. J.
(2007
). “Adaptation of the electrically evoked compound action potential (ECAP) recorded from Nucleus CI24 cochlear implant users
,” Ear Hear.
28
, 850
–861
.12.
Deller
, J. R.
, Hansen
, J. H. L.
, and Proakis
, J. G.
(2000
). Discrete-Time Processing of Speech Signals
(Institution of Electrical and Electronics Engineers Inc.
, New York
), pp. 117
–137
, 336–338, 373–380.13.
Deng
, L.
, and O'Shaughnessy
, D.
(2003
). Speech Processing: A Dynamic and Optimization–Oriented Approach
(Marcel Dekker Inc.
, New York
), pp. 53
–61
.14.
Dorman
, M. F.
, Loizou
, P. C.
, and Rainey
, D.
(1997
). “Speech intelligibility as a function of the number of channels of stimulation for signal processors using sine-wave and noise-band outputs
,” J. Acoust. Soc. Am.
102
, 2403
–2411
.15.
Dowell
, R. C.
, Seligman
, P. M.
, Blamey
, P. J.
, and Clark
, G. M.
(1987
). “Evaluation of a two-formant speech-processing strategy for a multichannel cochlear prosthesis
,” Ann. Otol. Rhinol. Laryngol.
96
, 132
–143
.16.
El-Jaroudi
, A.
, and Makhoul
, J.
(1991
). “Discrete all-pole modeling
,” IEEE Trans. Signal Process.
39
, 411
–423
.17.
Firszt
, J. B.
, Holden
, L. K.
, Reeder
, R. M.
, and Skinner
, M. W.
(2009
). “Speech recognition in cochlear implant recipients: Comparison of standard HiRes and HiRes 120 sound processing
,” Otol. Neurotol.
30
, 146
–152
.18.
Flanagan
, J. L.
(1955
). “A difference limen for vowel formant frequency
,” J. Acoust. Soc. Am.
27
, 613
–617
.19.
Flanagan
, J. L.
(1956a
). “Automatic extraction of formant frequencies from continuous speech
,” J. Acoust. Soc. Am.
28
, 110
–118
.20.
Flanagan
, J. L.
(1956b
). “Band width and channel capacity necessary to transmit the formant information of speech
,” J. Acoust. Soc. Am.
28
, 592
–597
.21.
Fu
, Q.
, Shannon
, R. V.
, and Wang
, X.
(1998
). “Effects of noise and spectral resolution on vowel and consonant recognition: Acoustics and electric hearing
,” J. Acoust. Soc. Am.
104
, 3586
–3596
.22.
Furuya
, K.
, and Kataoka
, A.
(2007
). “Robust speech dereverberation using multichannel blind deconvolution with spectral subtraction
,” IEEE Trans. Audio Speech Lang. Process.
15
, 1579
–1591
.23.
Geurts
, L.
, and Wouters
, J.
(1999
). “Enhancing the speech envelope of continuous interleaved sampling processors for cochlear implants
,” J. Acoust. Soc. Am.
105
, 2476
–2484
.24.
Hawks
, J. W.
(1994
). “Difference limens for formant patterns of vowel sounds
,” J. Acoust. Soc. Am.
95
, 1074
–1084
.25.
Hazrati
, O.
, and Loizou
, P. C.
(2012
). “Tackling the combined effects of reverberation and masking noise using ideal channel selection
,” J. Speech, Lang. Hear. Res.
55
, 500
–510
.26.
Hillenbrand
, J.
, Getty
, L. A.
, Clark
, M. J.
, and Wheeler
, K.
(1995
). “Acoustic characteristics of American English vowels
,” J. Acoust. Soc. Am.
97
, 3099
–3111
.27.
Hu
, Y.
, and Loizou
, P. C.
(2008
). “A new sound coding strategy for suppressing noise in cochlear implants
,” J. Acoust. Soc. Am.
124
, 498
–509
.28.
IEEE
(1969
). “IEEE recommended practice for speech quality measurements
,” IEEE Trans. Audio Electroacoust.
17
(3
), 227
–246
.29.
Kadir
, H.
(2008
). “Speech compression using Linear Predictive Coding
,” https://www.mathworks.com/matlabcentral/fileexchange/13529-speech-compression-using-linear-predictive-coding (Last viewed January 29, 2007).30.
Kewley-Port
, D.
, Burkle
, T. Z.
, and Lee
, J. H.
(2007
). “Contribution of consonant versus vowel information to sentence intelligibility for young normal–hearing and elderly hearing-impaired listeners
,” J. Acoust. Soc. Am.
122
, 2365
–2375
.31.
Koch
, D. B.
, Osberger
, M. J.
, Segel
, P.
, and Kessler
, D.
(2004
). “HiResolution and conventional sound processing in the HiResolution Bionic ear: Using appropriate outcome measures to assess speech recognition ability
,” Audiol. Neurootol.
9
, 214
–223
.32.
Kokkinakis
, K.
, and Loizou
, P. C.
(2011
). “The impact of reverberant self-masking and overlap-masking effects on speech intelligibility by cochlear implant listeners (L)
,” J. Acoust. Soc. Am.
130
, 1099
–1102
.33.
Loizou
, P. C.
(1998
). “Mimicking the human ear
,” IEEE Signal Process. Mag.
15
, 101
–130
.34.
Loizou
, P. C.
(1999
). “Signal-processing techniques for cochlear implants
,” IEEE Eng. Med. Biol. Mag.
18
, 34
–46
.35.
Loizou
, P. C.
(2007
). Speech Enhancement Theory and Practice
(Taylor & Francis
, London
), pp. 69
–93
.36.
Markel
, J. D.
, and Gray
, A. H.
(1976
). “Speech synthesis structures
,” in Linear Prediction of Speech
, edited by J. D.
Markel
and A. H.
Gray
(Springer-Verlag
, Berlin, Germany
), pp. 92
–128
.37.
McDermott
, H. J.
, McKay
, C. M.
, and Vandali
, A. E.
(1992
). “A new portable sound processor for the University of Melbourne/Nucleus Limited multielectrode cochlear implant
,” J. Acoust. Soc. Am.
91
, 3367
–3371
.38.
Neuman
, A.
, Wroblewski
, M.
, Hajicek
, J.
, and Rubinstein
, A.
(2010
). “Combined effects of noise and reverberation on speech recognition performance of normal-hearing children and adults
,” Ear Hear.
31
, 336
–344
.39.
Neuman
, A.
, Wroblewski
, M.
, Hajicek
, J.
, and Rubinstein
, A.
(2012
). “Measuring speech recognition in children with cochlear implants in a virtual classroom
,” J. Speech, Lang. Hear. Res.
55
, 532
–541
.40.
Nogueira
, W.
, Uchner
, A.
, Lenarz
, T.
, and Edler
, B.
(2005
). “A psychoacoustic ‘NofM’-type speech coding strategy for cochlear implants
,” EURASIP J. Appl. Signal Process.
18
, 3044
–3059
.41.
O'Shaunghnessy
, D.
(2008
). “Formant estimation and tracking
,” in Springer Handbook of Speech Processing
, edited by J.
Benesty
, N. M.
Sondhi
, and Y.
Huang
(Springer-Verlag
, Berlin, Germany
), pp. 213
–227
.42.
Parikh
, G.
, and Loizou
, P. C.
(2005
). “The influence of noise on vowel and consonant cues
,” J. Acoust. Soc. Am.
118
, 3874
–3888
.43.
Patrick
, J. F.
, and Clark
, G. M.
(1991
). “The Nucleus 22-channel cochlear implant system
,” Ear Hear.
12
, 3S
–9S
.44.
Peterson
, G.
, and Barney
, H.
(1952
). “Control methods used in a study of the vowels
,” J. Acoust. Soc. Am.
24
, 175
–184
.45.
Peterson
, G. E.
, and Lehiste
, I.
(1962
). “Revised CNC lists for auditory tests
,” J. Speech Hear. Disord.
27
, 62
–70
.46.
Rabiner
, L. R.
, Schafer
, R. W.
, and Rader
, C. M.
(1969
). “The chirp z-transform algorithm
,” IEEE Trans. Audio Electroacoust.
17
, 86
–92
.47.
Rubinstein
, J. T.
(2004
). “How cochlear implants encode speech
,” Curr. Opin. Otolaryngol. Head Neck Surg.
12
, 444
–448
.48.
Sadjadi
, S. O.
, and Hansen
, J. H. L.
(2013
). “Unsupervised speech activity detection using voicing measures and perceptual spectral flux
,” IEEE Signal Process. Lett.
20
, 197
–200
.49.
Schafer
, R. W.
, and Rabiner
, L. R.
(1970
). “System for automatic formant analysis of voiced speech
,” J. Acoust. Soc. Am.
47
, 634
–648
.50.
Seligman
, P. M.
, and McDermott
, H. J.
(1995
). “Architecture of the Spectra 22 speech processor
,” Otol. Rhinol. Laryngol.
104
, 139
–141
.51.
Seligman
, P. M.
, Patrick
, J. F.
, Tong
, Y. C.
, Clark
, G. M.
, Dowell
, R. C.
, and Crosby
, P. A.
(1984
). “A signal processor for a multiple-electrode hearing prosthesis
,” Acta Otolaryngol. Suppl.
413
, 135
–139
.52.
Shannon
, R. V.
, Zeng
, F. G.
, Kamath
, V.
, Wygonski
, J.
, and Ekelid
, M.
(1995
). “Speech recognition with primarily temporal cues
,” Science
270
, 303
–304
.53.
Skinner
, M. W.
, Clark
, G. M.
, Whitford
, L. a
, Seligman
, P. M.
, Staller
, J. S.
, Shipp
, D. B.
, Shallop
, J. K.
, Everingham
, C.
, Menapace
, C. M.
, Arndt
, P. L.
, Antogenelli
, T.
, Brimacombe
, J. A.
, Pijl
, S.
, Daniels
, P.
, George
, C. R.
, McDermott
, H. J.
, and Beiter
, A. L.
(1994
). “Evaluation of a new spectral peak coding strategy for the Nucleus 22 channel cochlear implant system
,” Am. J. Otol.
15
, 15
–27
.54.
Skinner
, M. W.
, Holden
, L. K.
, Holden
, T. A.
, Dowell
, R. C.
, Seligman
, P. M.
, Brimacombe
, J. A.
, and Beiter
, A. L.
(1991
). “Performance of post-linguistically deaf adults with the wearable speech processor (WSP III) and mini speech processor (MSP) of the nucleus multi-electrode cochlear implant
,” Ear Hear.
12
, 3
–22
.55.
Snell
, R. C.
, and Milinazzo
, F.
(1993
). “Formant estimation from LPC analysis data
,” IEEE Trans. Speech Audio Process.
1
, 129
–134
.56.
Spahr
, A. J.
, Dorman
, M. F.
, Litvak
, L. N.
, Van Wie
, S.
, Gifford
, R. H.
, Loizou
, P. C.
, Loiselle
, L. M.
, Oakes
, T.
, and Cook
, S.
(2012
). “Development and validation of the AzBio sentence lists
,” Ear Hear.
33
, 112
–117
.57.
Tao
, Z.
, Zhao
, H.
, Gu
, J.
, Tan
, X.
, and Wu
, J.
(2008
). “Speech feature extraction of cochlear implants on the basis of auditory perception wavelet transform
,” in Proceedings of the International Conference on Audiology, Language, and Image Processing (ICALIP'08)
, July 7–9
, Shanghai, China
, pp. 80
–86
.58.
Tong
, Y. C.
, Clark
, G. M.
, Seligman
, P. M.
, and Patrick
, J. F.
(1980
). “Speech processing for a multiple-electrode cochlear implant hearing prosthesis
,” J. Acoust. Soc. Am.
68
, 1897
–1899
.59.
Vandali
, A. E.
, Whitford
, L. A.
, Plant
, K. L.
, and Clark
, G. M.
(2000
). “Speech perception as a function of electrical stimulation rate: Using the Nucleus 24 cochlear implant system
,” Ear Hear.
21
, 608
–624
.60.
Wilson
, B. S.
, and Dorman
, M. F.
(2008
). “Cochlear implants: Current designs and future possibilities
,” J. Rehabil. Res. Dev.
45
, 695
–730
.61.
Wilson
, B. S.
, Finley
, C. C.
, Lawson
, D. T.
, Wolford
, R. D.
, Eddington
, D. K.
, and Rabinowitz
, W. M.
(1991
). “Better speech recognition with cochlear implants
,” Nature
352
, 236
–238
.62.
Wilson
, B. S.
, Finley
, C. C.
, Lawson
, D. T.
, Wolford
, R. D.
, and Zerbi
, M.
(1993
). “Design and evaluation of a continuous interleaved sampling (CIS) processing strategy for multichannel cochlear implants
,” J. Rehabil. Res. Dev.
30
, 110
–116
.63.
Wouters
, J.
, McDermott
, H. J.
, and Francart
, T.
(2015
). “Sound coding in cochlear implants: From electric pulses to hearing
,” IEEE Signal Process. Mag.
32
, 67
–80
.64.
Wouters
, J.
, and Vanden Berghe
, J.
(2001
). “Speech recognition in noise for cochlear implantees with a two microphone monaural adaptive noise reduction system
,” Ear Hear.
22
, 420
–430
.65.
Zapata
, J. G.
, Carlos
, J.
, Martín
, D.
, and Vilda
, P. G.
(2004
). “Fast formant estimation by complex analysis of LPC coefficients
,” in Proceedings from the European Signal Processing Conference (EUSIPCO 2004)
, September 6–10
, Vienna, Austria
, pp. 737
–740
.© 2018 Acoustical Society of America.
2018
Acoustical Society of America
You do not currently have access to this content.