Spraak verstaan in fluctuerend achtergrond geluid bij normaal en slechthorenden als functie van ruis niveau

Transcription

1 Spraak verstaan in fluctuerend achtergrond geluid bij normaal en slechthorenden als functie van ruis niveau Koenraad S. Rhebergen Ruben Pool Wouter A. Dreschler NVA Wintervergadering Vrijdag 3 januari 29

2 Overview Experiment I: the SRT as a function of noise level & noise type Experiment II: measuring the temporal resolution SRT vs temporal resolution Conclusions

3 Experiment I Background noise Silence Stationary Noise level - SRTq + 25 db 8 dba 8 Hz interrupted Duty cycle 5% 8 Hz interrupted Duty cycle 25% SRTq + 25 db 8 dba SRTq + 25 db 8 dba - 8 (HL < 2 db) - 11 (HL > 3 db & SRTq 6 dba) Two noise levels, to examine intensity dependence Two duty cycles, to gather more information on the listener s ability to listen into gaps in noise

4 Speech Reception Threshold in noise (db SNR) Noise level 8 dba Noise level 25 db SL SRT (db SNR) SRTn SRTi5 SRTi25 SRTn SL SRTi5 SLSRTi25 SL Noise Condition

5 Release of Masking (RoM) in 8 dba noise RoM (SRTn - SRTi) in 8 dba noise square: 8 dba noise condition RoM (db) RoM SRTi5 Noise condition RoM SRTi25

6 Speech Reception Threshold in noise (db SNR) Noise level 8 dba Noise level 25 db SL SRT (db SNR) SRTn SRTi5 SRTi25 SRTn SL SRTi5 SLSRTi25 SL Noise Condition SRTq : 28 db SNR (1.7) : 54 db SNR (7.2)

7 Release of Masking (RoM) in 25 db SL noise RoM (SRTn - SRTi) in 25 db SL circles: 25 db SL noise RoM (db) RoM SRTi5 Noise condition RoM SRTi25

8 SRT model (Plomp, 1978) 9 8 Quiet Stationary Speech level (dba) : Black symbol : white symbol Noise Level (dba)

9 SRT model (Plomp, 1978) 9 Quiet Stationary L S = log [ SRT q / + ( L + SRT)/ ], 8 Speech level (dba) : Black symbol : white symbol Noise Level (dba)

10 SRT model (Plomp, 1978) 9 Quiet Stationary L S = log [ SRT q / + ( L + SRT)/ ], 8 Speech level (dba) : Black symbol : white symbol Noise Level (dba)

11 SRT model (Plomp, 1978) 9 8 Quiet Stationary 8-Hz DC 25% L S = log [ SRT q / + ( L + SRT)/ ], Speech level (dba) SRT =α+ βl, L S = log [ SRT q / ( α+ ( β+ 1) L )/ + ], : Black symbol : white symbol Noise Level (dba)

12 Extended SRT model (Rhebergen et al., 2x) 9 8 Quiet Stationary 8-Hz DC 25% L S = log [ SRT q / + ( L + SRT)/ ], Speech level (dba) SRT =α+ βl, L S = log [ SRT q / ( α+ ( β+ 1) L )/ + ], : Black symbol : white symbol Noise Level (dba)

13 Extended SRT model (Rhebergen et al., 2x) 9 8 Quiet Stationary 8-Hz DC 5% 8-Hz DC 25% L S = log [ SRT q / + ( L + SRT)/ ], Speech level (dba) SRT =α+ βl, 2 L S = log [ SRT q / ( α+ ( β+ 1) L )/ + ], : Black symbol : white symbol Noise Level (dba)

14 Extended SRT model (Rhebergen et al., 2x) 9 8 Quiet Stationary 8-Hz DC 5% 8-Hz DC 25% L S = log [ SRT q / + ( L + SRT)/ ], Speech level (dba) SRT =α+ βl, 2 L S = log [ SRT q / ( α+ ( β+ 1) L )/ + ], : Black symbol : white symbol Noise Level (dba)

15 RoM vs Temporal Resolution Factor (TRF) As the SRT (db SNR) in Fluctuating noise is the RoM dependent on the presentation level. Therefore, the RoM might not be a good measure to compare the performances for & listeners at different noise levels TRF is defined as the ratio between the level differences of the three subjectively measured values; (Zwicker et al 1982)

16 RoM vs Temporal Resolution Factor (TRF) Measurement of the listeners hearing threshold in: Silence (THS) Interrupted (modulated) noise (MOD) Continous noise (CONT) TRF tone = (L CONT - L MOD ) / (L MOD - L THS ) (Zwicker et al 1982) TRF SRT = (LSRTn - LSRTi) / (LSRTi - LSRTq)

17 TRF for Speech vs SRT in stationary noise (SRTn) TRF for Speech (8 dba noise) TRF for Speech (SL noise)) 2, 2, 1,5 1,5 TRF for Speech 1,,5, TRF for Speech 1,,5, -,5 -,5-1, , SRTn (db SNR) SRTn (db SNR) : Black symbol : white symbol

18 TRF for Speech vs SRT in stationary noise (SRTn) TRF for Speech (8 dba noise) TRF for Speech (SL noise)) 2, 2, 1,5 Plot 1 Regr Plot 1 Pred1 1,5 Plot 1 Regr Plot 1 Pred1 TRF for Speech 1,,5, TRF for Speech 1,,5, -,5 -,5-1, SRTn (db SNR) -1, SRTn (db SNR) : Black symbol : white symbol

19 TRF for Speech vs SRT in interrupted noise (SRTi5) TRF for Speech (8 dba noise) TRF for Speech (SL noise)) 2, 2, 1,5 1,5 TRF for Speech 1,,5, TRF for Speech 1,,5, -,5 -,5-1, SRTi5 (db SNR) -1, SRTi5 (db SNR) : Black symbol : white symbol

20 TRF for Speech vs SRT in interrupted noise (SRTi5) TRF for Speech (8 dba noise) TRF for Speech (SL noise)) 2, 2, 1,5 1,5 TRF for Speech 1,,5, TRF for Speech 1,,5, -,5 Plot 1 Regr Plot 1 Pred1 -,5 Plot 1 Regr Plot 1 Pred1-1, SRTi5 (db SNR) -1, SRTi5 (db SNR) : Black symbol : white symbol

21 Audibility Calculations (ESII model Rhebergen, Versfeld & Dreschler, 26) SIIn vs TRF SRT SIIi5 vs TRF SRT 1, 1,,9,8,9,8,7,7,6,6 SII,5 SII,5,4,4,3,3,2,2,1,1, -,2,,2,4,6,8 1, 1,2 1,4 TRF SRT, -,2,,2,4,6,8 1, 1,2 1,4 TRF SRT : Black symbol : white symbol

22 Experiment II: temporal resolution Masking period patterns (Zwicker and Schorn, 198) Up-down method Noise level 7 db SPL Frequency:.5 1, 2 & 3 khz TRF tone = (L CONT - L MOD ) / (L MOD - L THS ) (Zwicker et al 1982)

23 Threshold vs TRF threshold vs probe level threshold vs Temporal Resolution Factor 8 2,5 Probe level (db SPL) Threshold 5Hz Threshold 1kHz Threshold 2kHz Threshold 3kHz Temporal resolution Factor 2, 1,5 1,,5, -,5 5Hz 1kHz 2kHz 3kHz , Threshold (db SPL) Threshold (db SPL)

24 Modeling threshold probe level Ludvigsen (1985) Ludvigsen noise level (db SPL) Delay time (ms) E FMF ( t) = E( T ) log( t/ T ) log( T f / T ) *[ E( T ) E( T f )],

25 Observed vs Predicted probe level threshold vs probe level Correlations Ludvigsen:.962 (p <.1) Probe level (db SPL) Threshold 5Hz Threshold 1kHz Threshold 2kHz Threshold 3kHz Frequency 5 Hz 1 khz 2 khz 3 khz Mean -7,5-6,5-4,3-4,9 Std. Deviation 3,8 2,8 3,3 2, Total -5,8 3,3 Threshold (db SPL)

26 TRF tone vs TRF SRT TRF tone vs TRF SRT (8 dba noise) : Green symbol : Red symbol 2,5 2, 1,5 TRF tone 1,,5, -,5-1, -1, -,5,,5 1, 1,5 2, 2,5 TRF SRT Average TRF value (.5, 1, 2 & 3 khz)

27 Conclusions At equal sensation level is the SRT in modulated noise in listeners on average lower (better) than the SRT in Listeners. There seems to be a relation between the TRF for tone & the TRF for speech (SRT) listeners seems to need more audible speech (i.e. higher SII value) in modulated noise for the observed SRT than in stationary noise

28 Fin End Ende Einde