relationship between perception of spectral ripple and speech recognition in cochlear implant and...
TRANSCRIPT
![Page 1: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/1.jpg)
Relationship between perception of spectral ripple and speech
recognition in cochlear implant and vocoder listeners
L.M. Litvak, A.J. Spahr, A.A. Saoji, and G.Y. Fridman
![Page 2: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/2.jpg)
L.M. Litvak, A.J. Spahr, A.A. Saoji, and G.Y. Fridman
Relationship between perception of spectral ripple
and speech recognition in cochlear implant and vocoder listeners
Frequency (Hz)
![Page 3: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/3.jpg)
Cochlear Implant usersVariability
Why?
Can we explain this variability by testing normal listeners?Where an explanation arise?Start from the beginning – the stimulation point.
![Page 4: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/4.jpg)
• Cochlear Implant: Auditory Nerve– Electric fields, overlap = distortion
• Normal Listener: Basilar membrane– Auditory filters, spread = decreased spectral resolution
Stimulation point
Frequency (Hz)Spe
ctra
l Lev
el
Frequency (Hz)Spe
ctra
l Lev
el
How do we change the spectral resolution in normal listeners?
![Page 5: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/5.jpg)
Vocoder Simulations• Vocoder – electronic device that synthesizes speech• Vocoder Simulations
– Reduces spectral information to 15 channels• Mimics CI processing
– Drop-off varied 5 – 40 dB/octave• Mimics variable spectral resolution
How do we measure the changes in normal listeners?
Frequency (Hz)
![Page 6: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/6.jpg)
Perception of Spectral RippleHow well can we represent spectral information in speech?
+ =
Frequency (Hz)
Spe
ctra
l Lev
el
![Page 7: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/7.jpg)
Spectral modulation threshold• Spectral modulation threshold (SMT)
– measure of spectral resolution– measures the spectral ripple perception
Will the varied spectral resolution demonstrate the same variability seen in CI word recognition scores?
![Page 8: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/8.jpg)
L.M. Litvak, A.J. Spahr, A.A. Saoji, and G.Y. Fridman
Relationship between perception of spectral ripple
and speech recognition in cochlear implant and vocoder listeners
![Page 9: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/9.jpg)
Methods• 25 CI users, 10 normal listeners• Normal listeners
– Vocoder simulations• Speech
– Separated in 15 bands– Multiplied by noise– Change rate of drop-off of noise spectrum
» Varies spread
• Tested for recognition of vowels and consonants
• Compare word recognition scores
Frequency (Hz)
![Page 10: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/10.jpg)
Results: Vowels
![Page 11: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/11.jpg)
Results: Consonants
![Page 12: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/12.jpg)
Results: Consonants
Primarily spectral cues
Primarily Temporal / Amplitude
![Page 13: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/13.jpg)
Results
• Normal listeners– SMT increase = decrease in word recognition
scores (WRS)– Decrease in WRS similar to CI listeners with similar
SMTs
• Variability in spread (due to SMT increase) of neural activity largely accounts for variability in CI users scores.
![Page 14: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/14.jpg)
Conclusions
• Main Finding:– Same slope between CI and normal listeners
• Spectral resolution = explanation of variability in CI users
• Subsidiary Finding:– Differences between vowels and consonants
• Temporal cues
![Page 15: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/15.jpg)
Questions
• Additional Factors– Age of subjects
• Alternative explanations– Other cues besides temporal cues– Frequency to place alignment problem
• Central plasticity
![Page 16: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/16.jpg)
![Page 17: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/17.jpg)
Confusion Matrix: Vowels
![Page 18: Relationship between perception of spectral ripple and speech recognition in cochlear implant and vocoder listeners L.M. Litvak, A.J. Spahr, A.A. Saoji,](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649d745503460f94a53f6c/html5/thumbnails/18.jpg)
Confusion Matrix: Consonants