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2. Sensorineural Hearing loss. Most common type of hearing lossAffects > 20 million in the US aloneCaused by physiological problems in the cochlea. 3. Traditional Hearing Aids. Amplification of frequency bandsAmplitude compressionWorks best in situations with high SNR. 4. Problems With Tr
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1. Towards a Cohort-Selective Frequency-Compression Hearing Aid Marie Roch¤, Richard R. Hurtig¥,
Jing Lui¤, and Tong Huang¤
2. 2 Sensorineural Hearing loss
Most common type of hearing loss
Affects > 20 million in the US alone
Caused by physiological problems in the cochlea
3. 3 Traditional Hearing Aids
Amplification of frequency bands
Amplitude compression
Works best in situations with high SNR
4. 4 Problems With Traditional Methods
Simple amplification insufficient
Individuals with severe hearing loss cannot perceive formants
5. 5 Preserving the formants Frequency domain compression [Turner & Hurtig 1999] permits preservation of formants
6. 6 Effectiveness
Clinical study of 15 hearing-impaired listeners showed improvement when listening to different groups
female talkers: 45% improvement
male talkers: 20% improvement
7. 7 Challenges
Not all voices require the same level of compression
Single setting leads to inappropriate levels of compression
8. 8 Adaptive thresholds Decision-based control mechanism
Establish cohorts and compress according to cohort class.
Some possible cohorts:
Phonological units
Pitch
Speaker “gender”
9. 9 Gender-based classifier Selected “gender” for first study.
Female, Male, Child
Classifier output more stable than with phonological approaches.
Broad support in the literature for the ability of both humans and machines to do this.
10. 10 Classifier Gaussian mixture models
Features extracted from 25 ms windows shifted every 10 ms
Energy
12 Mel-filtered cepstral coefficients (MFCC)
Time-derivatives of Energy & MFCC
11. 11 Control system architecture
12. 12 LDC SPIDRE Corpus Conversational telephone speech
Band-limited 8 kHz
Mu-law encoded
Endpointed with the NIST/Kubala endpointer
Train
Single sides of same-gender phone calls
25 male & female
Test
87 annotated cross-gender phone calls
About 7 hours of calls (~5 min. each)
13. 13 SPIDRE Classification Results
14. 14 Error analysis Many errors occurred in fricatives which have high frequency energy
15. 15 Evalution on TIMIT 630 speakers, clean speech 16 kHz corpus
Train: 25 male, 25 female. Test 413 male, 167 female.
16. 16 Median Smoothing (SPIDRE)
17. 17 Conclusions & Future Work Classifier-based control systems
feasible
can be applied to other signal enhancement algorithms
need not be limited to the cohorts presented today (e.g. auditory scene analysis)