Amplitude Compression: Timing is Everything

Transcription

1 Amplitude Compression: Timing is Everything Andrea Pittman Arizona State University Funded by a grant from Oticon A/S

2 Output (db SPL) Wide Dynamic Range Compression Input (db SPL)

3 Output (db SPL) Wide Dynamic Range Compression Input (db SPL)

4 The Problem with Slow-Acting Compression : :

5 Gain (db) Level (db SPL) The Problems with Fast-Acting Compression 110 Fast Compression Time

6 Gain (db) (db) Level Level (db (db SPL) SPL) The Problems with Fast-Acting Compression 110 Slow Compression Time

7 NOISE Output (db SPL) SPEECH The Problems with Fast-Acting Compression SNR: 20 db Input (db SPL)

8 NOISE Output (db SPL) SPEECH The Problems with Fast-Acting Compression SNR: 10 db Input (db SPL)

9 Adaptive Compression (SpeechGuard) Slowly follows gradual input changes Quickly reacts to large increases in input Quickly reacts to large decreases in input Slow Fast Slow

10 Adaptive Compression (SpeechGuard) Rapidly reduce gain for high-level sounds Rapidly re-establish gain for lower-level sounds Better preserve the shape of the acoustic waveform Optimize the signal-to-noise ratio

11 Purpose Determine the benefits of adaptive compression to children s and adult s ability to manage complex listening environments. Complex Environments: Speech perception Perception of environmental sounds Visual task

12 Participants Children 20 with normal hearing 7-12 years 15 with hearing loss Adults 7-12 years 21 with normal hearing years 26 with hearing loss years years

13 Amplitude Compression Parameters Single compression model 4 channels Compression ratio = 3:1 Knee point of 40 db SPL Timeconstants Slow: attack ~20ms, release ~800ms Fast: attack ~10ms, release ~40ms Adaptive: Speech Guard

14 Auditory Stimuli +10 db Trigger Target +4 db Playground Noise

15 Auditory Stimuli Trigger Target Playground Noise Non-overlapping Overlapping

16 Auditory Stimuli Door Apple Trigger Dog Cough Target Playground Noise Words Environmental Sounds

17 Complex Task Animal Person Thing?? Person Food Animal??

18 A: 20 ms R: 800 ms A: 10 ms R: 40 ms A: Var R: Var

19 Listening Conditions NON- OVERLAPPING SPEECH ENVIRONMENTAL SOUNDS OVERLAPPING

20 RESULTS

21 Words NORMAL HEARING HEARING LOSS

22 Words NORMAL HEARING HEARING LOSS

23 Sounds NORMAL HEARING HEARING LOSS

24 Sounds NORMAL HEARING HEARING LOSS

25 Words Sounds NORMAL HEARING HEARING LOSS

26 Conclusions Listeners with hearing loss had difficulty with: Partial acoustic information Fast-acting compression Environmental sounds Adaptive compression Improved recognition of speech and environmental sounds

27 Thanks to Funding Oticon Professional Assistance Kamilla Angelo Thomas Behrens Michael Nilsson Research Assistants Ashley Pederson Madalyn Rash Amanda Willman Tia Mulrooney Local Facilities Phoenix Children s Hospital Children s Rehabilitative Services Mesa School District ASU Speech and Hearing Clinic