Alternative Assessments Alternative Assessments for Musiciansfor Musicians

Marshall Chasin, Marshall Chasin,

AuD., M.Sc., Reg. CASLPO, Aud(C)AuD., M.Sc., Reg. CASLPO, Aud(C)

Musicians’ Clinics of CanadaMusicians’ Clinics of Canada

Why do any tests?Why do any tests?

Hearing loss preventionHearing loss prevention

Assessment of hearing aids for musicAssessment of hearing aids for music

(Assessment of musicians)(Assessment of musicians)

Hearing Loss PreventionHearing Loss Prevention

AudiometricAudiometric High frequency testingHigh frequency testing

• Actual bandwidth of hearingActual bandwidth of hearing• Notches in hearingNotches in hearing• Up to 12kHz vs. higher…Up to 12kHz vs. higher…

Non-audiometricNon-audiometric OAE (TTS analog)OAE (TTS analog) Speech in noise testsSpeech in noise tests

AudiometricAudiometric

High frequency artifactsHigh frequency artifacts Stinson (1988, JASA): minimal artifacts up to Stinson (1988, JASA): minimal artifacts up to

12kHz but large variance above this.12kHz but large variance above this. Minimized with proper earphones that have Minimized with proper earphones that have

both a smooth frequency response and wide both a smooth frequency response and wide bandwidth.bandwidth.

Monitor at TM with probe microphone to verify Monitor at TM with probe microphone to verify calibration.calibration.

Good test-retest reliability WITHIN subjects…Good test-retest reliability WITHIN subjects…

From: Nancy E. Vaughan, et al. 2002, Journal of Res. Rehab. DevelopmentFrom: Nancy E. Vaughan, et al. 2002, Journal of Res. Rehab. Development (within subjects)(within subjects)

The right earphone for the right The right earphone for the right frequency…frequency…

The 4000 Hz notchThe 4000 Hz notch

Results from a 28 mm long ear canal that Results from a 28 mm long ear canal that functions as a quarter wavelength functions as a quarter wavelength resonator…resonator…

F = (2k-1) v/4LF = (2k-1) v/4L

Odd number multiples of 4000 Hz… Odd number multiples of 4000 Hz… 12kHz, 20kHz,…12kHz, 20kHz,…

The 4000 Hz notchThe 4000 Hz notch

Even though the ear canal is on average, Even though the ear canal is on average, 28 mm…28 mm…

F = 340,000 mm/sec/4x28 mm = 3035 HzF = 340,000 mm/sec/4x28 mm = 3035 Hz

But… F = 2700 HzBut… F = 2700 Hz

The eardrum adds several mm of acoustic The eardrum adds several mm of acoustic length because of its compliance. (3-4 mm)length because of its compliance. (3-4 mm)

The 4000 Hz notchThe 4000 Hz notch

BUT, for higher frequencies, the eardrum BUT, for higher frequencies, the eardrum does not supply the extra several mm of does not supply the extra several mm of acoustic length, so that odd number acoustic length, so that odd number multiples of the 4000 Hz notch is really multiples of the 4000 Hz notch is really higher than 12kHz (… more like 14-higher than 12kHz (… more like 14-15kHz).15kHz).

High frequency audiometryHigh frequency audiometry

So,…. With the proper earphones and within So,…. With the proper earphones and within subjects, one can reliably test in the higher subjects, one can reliably test in the higher frequency range.frequency range.

(1) higher frequency notches (14k-15kHz) may (1) higher frequency notches (14k-15kHz) may occur prior to the 4000-6000 Hz notches.occur prior to the 4000-6000 Hz notches.

(2) 10k-12k thresholds may help identify (2) 10k-12k thresholds may help identify etiology. (eg. Violins have an 8kHz notch).etiology. (eg. Violins have an 8kHz notch).

(3) good reliability within subjects (longitudinal).(3) good reliability within subjects (longitudinal).

Ear Q softwareEar Q software

Ear Q is one of many software products Ear Q is one of many software products that can allow your lap top to become a that can allow your lap top to become a (high frequency) audiometer…(high frequency) audiometer…

High frequency audiometryHigh frequency audiometry

Interesting trivia…Interesting trivia…

Ashihara (2007) JASA: humans can hear Ashihara (2007) JASA: humans can hear up to 28kHz.up to 28kHz. As long as presentation level is 100 dB SPL.As long as presentation level is 100 dB SPL.

Non-audiometric testsNon-audiometric tests

OAEOAE Poor test-retest reliability between subjects.Poor test-retest reliability between subjects.

But, good test-retest reliability within subjects.But, good test-retest reliability within subjects.

• Like high frequency audiometry, can be used for Like high frequency audiometry, can be used for longitudinal testing of differences within subjects.longitudinal testing of differences within subjects.

OAEsOAEs

Can be used to assess temporary Can be used to assess temporary changes (eg. TTS).changes (eg. TTS).

Can be used to assess deterioration over Can be used to assess deterioration over the years.the years.

Can be used to test non-audiometric Can be used to test non-audiometric frequencies.frequencies.

Otoacoustic EmissionsOtoacoustic Emissions(Drummer - symmetrical “hearing”)(Drummer - symmetrical “hearing”)

Disortion Product OAEs for Mr. WJ.

-20

-10

0

10

20

30

0 2000 4000 6000 8000

Frequency (Hz)

dB

SP

L

Left ear

Right ear

Otoacoustic EmissionsOtoacoustic Emissions(Lead singer moved away from (Lead singer moved away from

drummer)drummer)

Mr. GJ initially and after 6 month recheck

-20

-10

0

10

20

0 5000 10000

Frequency (Hz)

dB

SP

LLeft ear -initially

Right ear -initially

Left ear - after6 monthrecheck

OAE “notch” at 5000 Hz and not OAE “notch” at 5000 Hz and not measured on audiometry...measured on audiometry...

OAE Loss at a Non-Audiometric Frequency

-20

-15

-10

-5

0

5

10

15

0 1000 2000 3000 4000 5000 6000 7000

Frequency (Hz)

dB

SP

L 4 weeks after "TTS"

2 weeks after "TTS"

Day after "loud gig"

What about assessment of hearing What about assessment of hearing aids for music?aids for music?

““Traditionally” one looks at pre-selection…Traditionally” one looks at pre-selection…

Wide bandwidthWide bandwidth WDRCWDRC Appropriate compressionAppropriate compression High input limiting level or equivalentHigh input limiting level or equivalent Disabled feedback and noise managementDisabled feedback and noise management 6 dB lower gain and output for same level6 dB lower gain and output for same level

but,… how do you evaluate aids?but,… how do you evaluate aids?

(1) Ensure that electro-acoustic settings (1) Ensure that electro-acoustic settings and parameters are correct.and parameters are correct.

(2) An assessment scale (like the AI)….(2) An assessment scale (like the AI)….

Development of an assessment Development of an assessment scale…scale…

Gabrielsson et al. (1974, 1991)Gabrielsson et al. (1974, 1991)

Cox and Alexander (1983)Cox and Alexander (1983)

Chasin and Russo (2004)Chasin and Russo (2004)

Development of an assessment Development of an assessment scale…scale…

Loudness- music is sufficiently loudLoudness- music is sufficiently loud Fullness- music is full (vs. thin)Fullness- music is full (vs. thin) Crispness-music is clear and distinct (vs. Crispness-music is clear and distinct (vs.

blurred or diffuse)blurred or diffuse) Naturalness- as I remember it (as if there Naturalness- as I remember it (as if there

was no aid there)was no aid there) Overall fidelity- dynamics not constrainedOverall fidelity- dynamics not constrained

Development of an assessment Development of an assessment scale…scale…

Cannot develop an AI (or SII) for music since Cannot develop an AI (or SII) for music since there is no long term spectrum as there is for there is no long term spectrum as there is for speech.speech.

Can develop correlations (and regressions) Can develop correlations (and regressions) between these five outcomes measures and between these five outcomes measures and various bands of music.various bands of music.

Successive low pass filtering and the five Successive low pass filtering and the five perceptional parameters will be assessed at perceptional parameters will be assessed at each of the cutoff frequencies of the LP filters.each of the cutoff frequencies of the LP filters.

Development of an assessment Development of an assessment scale…scale…

Goal: determine which perceptual Goal: determine which perceptual parameters (or combination of parameters (or combination of parameters) correlates with which parameters) correlates with which frequency band, similar to an SII measure.frequency band, similar to an SII measure.