2. Vowel formant discrimination in high- fidelity speech by hearing-impaired listeners. Diane Kewley-Port, Chang Liu (also University at Buffalo,) T. Zachary Burkle Indiana University, SPHS Presented at the Acoustical Society of America Meeting, Austin, TX, Nov. 11, 2003.

3. Thanks to SPL Lab members Larry Humes (Investigator) Maureen Coughlin (Audiologist, ABD) Kelley Anderson (Research Assistant) Bill Mills (Programmer)

4. Formant Discrimination Just noticeable difference between standard vowel and one with shifted formant. Psychophysical procedures to determine thresholds formant frequency,  F (Hz). For 10+ years, experiments have systematically varied conditions, phonetic context, F0, noise etc. Purpose: Examine formant thresholds for hearing-impaired listeners (HI) in nearly natural speech, including sentences

5. High-Fidelity Speech To preserve naturalness, use STRAIGHT (Kawahara et al., 1999) synthesis Stimulus Samples for word “bad” –Sentence –Word (standard vowel) –Word (10% F1 increment, NH, optimal listening Weber Fraction = 1.5%)

7. Experimental Factors for HI study Formant Frequency: / I E Q Ã / F1 & F2 Audibility: 70 dB SPL partial vs. 95 dB SPL fully Linguistic Context: isolated vowels, words, sentences Sent + ID task: Sentence discrimination only vs. Sentence discrimination + ID

8. Hearing Impaired Listeners 21 – 55 years old, N = 5 Mild – moderate, high-frequency loss

9. Procedures Day 1 Screening Days 2-4 Training Days 5-23 Testing Linguistic Context (ISO, Word, Sent) and Sent + ID blocks randomized daily 95 vs. 70 dB SPL levels fixed each day

10. Audibility (70 vs 95) No Linguistic Context Yes (ISO, Word, Sent) Sent + ID task No Explain with figures Summary Threshold Results FactorSignificant Formant Frequency (8) Yes

11. 1) Formant Frequency 2)Audibility

13. 3) Linguistic Context. Thresholds different Why? Post-hocs, only  F word <  F Sent

14. Reversal,  F Iso >  F Word

15. Comparison HI to NH (Hi-Fi)

16. Thresholds Hi-Fi vs. Synthetic Speech Richie, Kewley-Port, & Coughlin (2003) reported  F for isolated formant synthesized vowels (Syn) for HI Liu & Kewley-Port (2003) report for NH no difference Hi-Fi and Syn for isolated vowels and words Predict that thresholds for our Hi-Fi vowels same as Syn vowels from Richie et al.

17. Hi-Fi elevated by 150%

18. Summary Formant discrimination by HI significantly effected by –Formant Frequency –Linguistic Context –Speech quality (Hi-Fi harder) Surprising Hi-Fi threshold comparisons – Thresholds for softer sentences better than louder –  hresholds for words better than isolated vowels

19. Baseline Thresholds Normal Hearing Listeners (NH) Formant Synthesized (Syn) Female Isolated (ISO) Vowels F1 & F2 Four Vowels: / I E Q Ã /

20. Linguistic Context Syn

21. Added ID Task

22. Audibility versus Pathology Vowels fully audible 70 dB NH, 95 dB HI  F2 elevated by 200 %