Following this presentation, learners should be able to select and - PDF document

10/17/2018 Cory Portnuff, AuD, PhD, CPS/A Board Certified, Clinical Audiologist UCHealth Assistant Clinical Professor Department of Otolaryngology, School of Medicine University of Colorado Denver  Following this presentation, learners should be able to select and dispense hearing protection which is appropriate and effective for musicians and music consumers.  Following this presentation, learners should be able to better program hearing aids for music and be able to recommend technology options for music listening. 1

10/17/2018  How can a musician reduce his/her exposure?  Exposure is Level + Time  Reduce playing level  Reduce playing time  Reduce exposure from other instruments  E.g. highly directional instruments on risers 2

10/17/2018  Earplugs  In-Ear Monitors  Both HPDs and Noise Controls Musicians and earplugs… • Many musicians are resistant to earplugs • Good, but not great fidelity (loss of some timbre) • Auditory memory of high levels • Comfort over playing time • Audibility of own instrument and others • Bad experiences with foam earplugs 3

10/17/2018  Custom  9, 15, 25 dB of attenuation  $150-$200  Requires ear impressions by an audiologist  Universal fit  “Ety-plug”, “ER-20”  20 dB of attenuation  $12-20 4

10/17/2018  Use REAT measures with each earplug fit, either under Circumaural earphones or in soundfield with masking to the contralateral ear (~50 dB SL).  At minimum: 250 Hz, 4000 Hz  Better: 250, 500, 1000, 2000 Hz  Best: ▪ 250, 1000, 2000, 4000 Hz ▪ 250, 500, 2000, 4000 Hz 9  REAT vs. MIRE Open ear Probe mic Modified probe Portnuff & Price, 2016 5

10/17/2018  Is this the best you can offer me? 11  Auditory memory and music  Avoiding performance injury  Ear training  Enrollment in a hearing conservation program  Annual review of exposure & exposure controls  Annual evaluation of hearing  Annual review of hearing protection use  Annual education and training about hearing 12 6

10/17/2018  Etymotic Research Music Pro 7

10/17/2018 “… about 50,000 working musicians use IEMs” - Michael Santucci (Beck, 2016)  Isolation? 8

10/17/2018  Improved sound quality & stereo sound  Improved pitch perception, timing  Consistent sound between venues.  Mobility  Reduced risk of feedback  Reduced vocal fatigue  Lower sound levels for audience ACRYLIC SILICONE  Many companies  One company  Variable seal  Excellent seal  Can be fit with canal coating or  Somewhat bulky vinyl canal to improve seal  Most expensive (though some cost  Wide cost range range) 9

10/17/2018 Federman & Ricketts (2008)  Federman & Ricketts (2008)  10

10/17/2018  Requires education and training! A priori, Musicians care about performance, not about preserving hearing.  Occlusion  Deep fit helps  Difficulty hearing stage noise  Take one out?  Stage can be miked  Sensaphonics 3D Active Ambient system 11

10/17/2018 23  As audiologists, we’re trained that the most important thing for our patients is COMMUNICATION Are hearing aids a communication tool or a quality-of-life tool? (what would CMS say about this?) 24 12

10/17/2018  Think about hearing aid features and signal processing. What are the main features of a hearing aid that are targeted at hearing speech well? 25  WDRC to ensure audibility  Expansion to reduce low-level sound annoyance  Limited MPO for comfort  Directional microphones for noise  Noise reduction & speech enhancement algorithms  Anti-feedback systems 26 13

10/17/2018  Long term average spectrum  Speech: low-frequency emphasis, some lower-intensity high frequency components  Music: Variable in both frequency and intensity. Significant dynamic range. 27 28 14

10/17/2018 (Chasin 2014) 29  Overall intensity  Speech: 65 dBA @ 1m. ± 12 dB ▪ Range: 53-77 dB SPL ▪ Shouted speech: up to 90 dBA  Music: Wide range. ▪ Brushes in a jazz song: 20-30 dBA ▪ Brass in Wagner’s Ring Cycle: 105 dBA, peaks at 120 dBA ▪ (Recorded music can be any level) 30 15

10/17/2018  Crest factors  Speech: 12 dB  Music: 14-20 dB 31  Discrimination vs. Quality components  Speech is mostly low-frequency energy and high frequency clarity (AI). Quality is important, but not critical.  Music perceptual requirements depends on the instrument…. Pitch discrimination required, timbre (quality) is key. ▪ Violins need to hear the balance between low and high frequencies. ▪ Clarinets only need to hear the lower frequency energy. 32 16

10/17/2018  WDRC compression  Reduces dynamic range Croghan et al 2014  Compression time constants matter 33  Long term average spectrum  Effect of WDRC? WDRC warps the signal envelope, reducing the spectral and temporal contrasts that listeners commonly utilize in music perception (Plomp, 1988).  Effect of multi-channel amplification? ▪ Interchannel distortion 34 17

10/17/2018  Overall intensity  Effect of WDRC?  Effect of MPO limits (peak compression)? 35  Crest factors  Effect of WDRC on dynamic range?  Effect of transient management algorithms?  Effect of feedback suppression algorithms?  Effect of speech enhancement/noise reduction? 36 18

10/17/2018  Discrimination vs. quality ANY modification of the sound signal is distortion Some distortion is helpful – some is not 37  WDRC to ensure audibility  Expansion to reduce low-level sound annoyance  Limited MPO for comfort  Directional microphones for noise  Noise reduction & speech enhancement algorithms  Anti-feedback systems 38 19

10/17/2018 GROUP QUESTION… What are the components of a hearing aid? 39 What are the key components for music? 40 20

10/17/2018  The Analog to Digital Converter 41  Most hearing aids have some degree of limiting of inputs >85 dB SPL  Let’s listen! http://www.chasin.ca/distorted_music/  Limiting at: 115 dB SPL, 105 dB SPL, 96 dB SPL, 92 dB SPL, and 115 dB SPL 42 21

10/17/2018 43 44 22

10/17/2018 45  Dynamic range also limited by processor –  16 bit = 96 dB. 24 bit = 144 dB 46 23

10/17/2018 47  16 bit minimum, though most manufacturers are moving to 24 or 32 bit systems.  “24” bit systems are really closer to 18-19 bits… but may allow up to 119 dB SPL inputs.  Multi-core DSP chips allow for faster processing. 48 24

10/17/2018  Increasing every day.  Is this a good thing? 49  Each channel “crossover” has the potential for distortion products  Worse with different compression ratios in adjacent channels 50 25

10/17/2018  Variable, hearing aid to hearing aid.  Generally, fast attack times  Release times vary significantly. 51  Transient management  Feedback suppression  Noise reduction  Speech enhancement 52 26

10/17/2018  One channel  No advanced features But, what do we do about the real world of audiology? 53  Consider the input…  “Lower the (input) volume, increase the Gain”  Chasin, 2014  Physically reduce the input  Digital shifting of dynamic range? 54 27

10/17/2018 55 56 28

10/17/2018 57  Consider input characteristics of the hearing aid, including patient’s needs.  Consider modifying microphone as needed. 100 90 80 O u tp u t (d B S P L ) 70 60 50 40 Chasin, 2008 30 20 10 0 0 2000 4000 6000 8000 10000 Frequency (Hz) Unattenuated output Adhear or Scotch Tape Adhear and Whiteout 58 29

10/17/2018  Change the input  Microphone: Use of an FM system or remote microphone (designed for higher input, close to mouth)  Recorded music: Direct audio input 59  Compression time constants  Slowest release possible! Preserves temporal envelope. ▪ Oticon “identities”  Compression kneepoints  5-8 dB above speech is ideal  Reduced compression ratio 60 30

10/17/2018  Turn off advanced features…  Noise reduction  Speech enhancement  Frequency lowering  Transient management  Tinnitus maskers  Probably automatic directional microphones 61  MPO  Max it out, unless you have loudness tolerance issues.  If so, OSPL 90 should be 6 dB higher than that for speech, to account for higher crest factors of music *Note – this only matters for live music/loud music. 62 31

10/17/2018  MOST:  Increase low frequency gain  Attempt to “widen bandwidth”  SOME:  Reduce compression ratios  Turn off some advanced features  A FEW:  Change compression constants to long release times 63  VERY FEW:  Turn off feedback cancellation  Turn off frequency lowering (if enabled when music program is created)  Shift threshold kneepoint up  Modify input dynamic range 64 32

10/17/2018  In a live music setting, is a hearing aid necessary for the patient?  What about recorded music? 65  Hearing aids are not ideal, on face, for music  Hearing aids can be modified for speech  Some are better than others out of the box!  Always consider the music input  Live music, loud music, soft music?  Will it overdrive the A/D converter? 66 33