musicians and the prevention of hearing loss dr. marshall chasin, aud, m.sc., reg. caslpo, aud(c),...

Musicians and the Prevention Musicians and the Prevention of Hearing Lossof Hearing Loss

Dr. Marshall Chasin, AuD, M.Sc.,

Reg. CASLPO, Aud(C), Audiologist

Musicians’ Clinics of Canada,

Marshall.Chasin@rogers.com

October 2006

Musicians’ Clinics of CanadaMusicians’ Clinics of Canada

Powerpoints available on …Powerpoints available on …

www.randomizedtimer.net/music

Special issue on musiciansSpecial issue on musicians

Hearing Review, March 2006– (guest edited by Marshall Chasin)– www.hearingreview.com

www.musiciansclinics.comwww.musiciansclinics.com

Sections on:

Hearing loss FAQs

Hearing loss prevention articles

Summary fact sheets (instruments)

Performing arts injuries

Links section

Fligor (2003, 2006)Fligor (2003, 2006)

Auditory risk assessment of portable compact disc players:

On most CD disc players (depending on the type of music and the earphone used), caution should be exercised above volume 5 or 6.

One disc player he used (using a vertically oriented earphone) yielded excessive outputs even when as low as volume 3-4.

Fligor (2006)Fligor (2006)

CD player with Panasonic Supra CD player with Panasonic Supra aural headphones (Fligor, 2004)aural headphones (Fligor, 2004)

Jazz Rap/

R&B

Classical Country Pop Adult Dance

Peak SPL

110.8 116.9 96.7 120.7 118.9 121 111.6

Avg dBA

88.5 98.6 79.2 102.8 97.9 105.7 95

The 60/120 ipod RuleThe 60/120 ipod Rule

The Fligor Rule (2006):

Maximum settings to obtain 50% maximum dosage…

ipod volume at 60% for 120 minutes Depends on earphone used

– Some earphones “isolate” the ear.– Some earphones have different electro-acoustic

characteristics.

The 60/60 CD RuleThe 60/60 CD Rule

This is appropriate for CD playersThese are about 3 dB more intense than

ipods.“60% volume setting for 60 minutes”

Portable music is portable…Portable music is portable…

The volume control is turned up in the presence of background noise

50% volume control may be comfortable in quiet, but this same comfortable listening level may be 80% volume in noise.

Portable music is portable…Portable music is portable…

The “best” headphone is one that isolates you from the environment…

You won’t need to turn up the volume control in a noisy place.

BUT, you also lose warning cues!

BEWARE!!!

Zogby International (March ’06)Zogby International (March ’06)

69% would turn down the volume

42% would listen less often

36% would use special (isolator) earphones

So …So …

60/60 rule for CD players

60/120 rule for ipods

Use isolator earphones

BUT watch out for traffic!

… … and another thing…and another thing…

Use the MP3 players in both ears.

Some kids use one earphone for them and the other for their friend.

Because of LACK of binaural summation, the volume needs to be 6 dB more intense… this is equivalent to four times the damage.

Noisy Toys ….Noisy Toys ….

- Can potentially cause hearing loss

- Acoustic trauma can occur Occurs at or near the peak frequency of the acoustic

signal May or may not be at an audiometric frequency so

can easily miss the loss.

Jansson and Karlsson (1983)Jansson and Karlsson (1983)

Maximum limits for symphony orchestras are achieved at anywhere between 10 and 25 hours per week of playing.

Chasin and Chong (1991)Chasin and Chong (1991)

Levels in excess of 85 dBA were measured even during a relatively quiet etude at Canada’s National Ballet with a peak level of 126 dBA.

Maximum Levels for InstrumentsMaximum Levels for Instruments(Wagner Ring Cycle: Camp and Horstman, 1992)(Wagner Ring Cycle: Camp and Horstman, 1992)

Instrument Peak Level (dB SPL)

French Horn 107

Bassoon 102

Trombone 108

Tuba 110

Trumpet 111

Violin 109

Clarinet 108

Percussion >120

(Amplified Guitar >115)

Chasin (2006)Chasin (2006)

With musicians, hearing loss With musicians, hearing loss is not as significant as …is not as significant as …

Tinnitus

Pitch perception problems

Two Factors Affecting Hearing LossTwo Factors Affecting Hearing Loss

Intensity (dBA)

Duration (hours)

……. 3 dB exchange rate

BUT ……….BUT ……….

Lindgren and Axelsson (1983)Lindgren and Axelsson (1983)

Temporary threshold shift was equal in 4 out of 10 subjects who were exposed to noise and music of equal energy, but greater for the noise exposure in the other 6 subjects.

HHöörmann et al. (1970)rmann et al. (1970)

Studied the emotional effects on TTS at 4kHz.

“reward”group had TTS of 12.8 dB“punishment” group had TTS of 18.1 dB

Swanson et al. (1987)Swanson et al. (1987)

Studied the effects of liking music on TTSGroup 1: Liked pop musicGroup 2: Disliked pop music

TTS (Group 1) < TTS (Group 2)

Liking The MusicLiking The Music

Role of efferent pathways– Musicians have greater efferent suppression than non-

musicians (Mecheyl et al., 1995, Perrot et al., 1999, Brashears et al., 2003)

Stress resulting in chemical changes in cochlea

Three Factors Affecting Hearing LossThree Factors Affecting Hearing Loss

Intensity

Duration

“Liking the music”

Stapedial ReflexStapedial Reflex

Zakrisson et al. (1980) studied unilateral Bell’s Palsy in humans.

TTS was 10 dB greater in de-innervated ear than normally functioning ear.

Borg et al. (1983) surgically cut stapedius muscle unilaterally in rabbits.

PTS was 30 dB greater in operated ear.

Stapedial Reflex and MusicStapedial Reflex and Music

Music is intermittent … allows reflex to “reset”.

Industrial noise tends to more steady state and reflex is only useful for first 10-15 seconds.

Four Factors Affecting Hearing LossFour Factors Affecting Hearing Loss

Intensity

Duration

“Liking the music”

Stapedial reflex

Individual FactorsIndividual Factors

Efferent neurological effects (eg. Lonsbury-Martin)– Musicians have greater efferent suppression than non-musicians (Mecheyl

et al., 1995, Perrot et al., 1999, Brashears et al., 2003)

Inaccurate patient noise exposure history

Genetic predisposition (eg. Kujawa)

Differing bio-chemical cochlear content– Individual factors– Environmental contributions (eg. Ototoxicity)– Availability of oxygen to cochlea

Effects of Physical Fitness at 4kHz Effects of Physical Fitness at 4kHz (Alessio et al., (Alessio et al.,

2002)2002)

Age/Fitness Low Medium High

Teens 2.0 2.2 0.75

50-60 13.5 11.3 13.0

60-80 34.5 21.2 14.2

Five Factors Affecting Hearing Five Factors Affecting Hearing LossLoss

Intensity

Duration

“Liking the music”

Stapedial reflex

(Individual factors)

… … Musicians are “slightly” less prone Musicians are “slightly” less prone to hearing loss than workers …to hearing loss than workers …

Limited duration each week

Liking the music

Stapedial reflex

Intermittent nature of the music

Effective quiet (critical levels)

Estimates of Effective Quiet (E.Quiet)Estimates of Effective Quiet (E.Quiet)

Freq. (Hz)

E.Quiet (dBA)

Clarinet (dBA)

Violin (dBA)

Trumpet (dBA)

250 77 72-82 75-84 75-98

500 75-85 73-84 75-87 76-98

1000 81-82 69-81 71-78 70-87

2000 77-78 66-74 70-74 66-77

4000 74-76 56-62 59-65 60-67

Effective QuietEffective Quiet(note similarity to music spectrum vs. noise!)(note similarity to music spectrum vs. noise!)

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Frequency (Hz)

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Rockers less prone to hearing loss!!!Rockers less prone to hearing loss!!!

Hart et al. (1987)…. Only 30% of rockers had hearing loss.

vs.

Royster et al. (1991) …. 52% for classical music.

1. Rockers only are subjected to loud music for several hours per week.

2. Enjoyment of music

3. Stapedial reflex (sings along?)

How I Assess a MusicianHow I Assess a Musician

Routine audiometry (pure tones, speech testing and impedance).

If asymmetries, then ABR/MRI- explained (eg. Violins, drummers)- unexplained (eg. unrecalled acoustic traumas, neuromas)

Otoacoustic emission testing

Real Ear Measurement of their instrument

Audiometric AsymmetriesAudiometric Asymmetries

Industrial exposure is (usually) symmetrical– Highly reverberant locations– Predominantly low-frequency noise

Music exposure can be asymmetrical– Low reverberant locations– Significant mid- and high-frequency music energy

Head and body shadow effects

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

Disortion Product OAEs for Mr. WJ.

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Left ear

Right ear

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

from drummer)from drummer)Mr. GJ initially and after 6 month

recheck

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LLeft ear -initially

Right ear -initially

Left ear - after6 monthrecheck

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

OAE Loss at a Non-Audiometric Frequency

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L 4 weeks after "TTS"

2 weeks after "TTS"

Day after "loud gig"

AAA poster session on OAEsAAA poster session on OAEs

Lisa Battani, “Effects of cigarette smoking on DPOAE”– Greater effect (reduction) seen in higher

frequencies. Vascular? Ototoxicity?

Real Ear MeasurementReal Ear Measurement

REM is modified to assess “external” stimuli

Disable the reference microphone and disable the speaker

eg. Audioscan: “stimulus level = 0 dB”

Frye: “stimulus off”

Perform a sweep with a low-frequency, a mid-frequency, and a high-frequency sound at quiet, medium, and loud levels.

Real Ear MeasurementReal Ear Measurement

RECALL… Unlike noise, music has significant mid- and high-frequency energy.

REM can (should) be performed at TM to take advantage of ear canal resonances.– Music enhanced by 17 dB at 3kHz over sound field.– Industrial noise is not enhanced in this region (except

impulse noise).

What to do with the information?What to do with the information?

The REM data will provide information on the relative contribution of noise exposure from that instrument.

Draw a picture of the noise environment, to see who else can be the culprit (eg. Drummer to the rear?)

Hearing Protection AlternativesHearing Protection Alternatives

ER-15: (1988+, Etymotic Research)

Custom made uniform attenuator provides 15 dB of attenuation up to 8000 Hz. It uses an element that interacts with an inductance to provide a 3000 Hz resonance, thus off-setting the loss of the ear canal resonance.

ER-25: (1992+)

Custom made uniform attenuator provides 25 dB of attenuation up to 6000 Hz.

Hearing Protection AlternativesHearing Protection Alternatives

ER-15 SP:Similar to ER-15 but LESS attenuation above 4000 Hz.

ER-9:Custom made uniform attenuator provides 9 dB of attenuation.

ER-20: ( HI-FI)Non-custom earplug with a slight high-frequency roll-off. Costs about $10-$12.

Hearing Protection AlternativesHearing Protection Alternatives

Vented/tuned earplugs:

Similar to filtered earplugs, except uses a SAV down the main sound bore. In its most open position is acoustically transparent below 1500 Hz…. almost….

Other Hearing Protection Other Hearing Protection AlternativesAlternatives

Other alternatives exist:

– Bilsom “Natural Sound Technology” (NST)

– (Digital) signal processing approaches

– Other vented/tuned approaches Variable venting schemes Variable (acoustic) filtering schemes

Earplugs and Auditory DangerEarplugs and Auditory Danger

Instrument Danger Earplug

Violin/Viola Violin/Viola ER-15

Woodwinds Percussion ER-15/

vented-tuned

Brass Brass/Percussion ER-15

Percussion Percussion ER-25

Amplified Instruments

Loudspeakers/

Drums

ER-15

Verifying AttenuationVerifying Attenuation

Real Ear Measurement– REUR - REOR (“unaided” – “aided”)– Perform at 70 dB or greater

Functional attenuation– Threshold with hearing protector in place – “unaided”– 2 dB steps (standard error = 2.8 dB)

Covering the “opening” of the hearing protector– subjective

14 Year Follow-up for ER-Earplugs14 Year Follow-up for ER-Earplugs

Survey of 850 earplug recommendations:

1990: 32% decided to get them

1995: 64% decided to get them

1997: 72% decided to get them

2005: 94% decided to get them

Follow-up for ER-EarplugsFollow-up for ER-Earplugs

Survey of 425 users:

83% still wearing them

14% changed to a different type (usually less)

3% did not like them (usually French Horn players)

Vented/tuned earplugsVented/tuned earplugs

Resonant Frequency α area

LoVe

Improved vocal awareness as frequency of the vent resonance is decreased. (decrease area and increase L)

Vented/tuned earplugsVented/tuned earplugs

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The wrong hearing protection can be The wrong hearing protection can be worse than none at all…worse than none at all…

A 25 year old drummer read that he needed to use earplugs.

He started using industrial strength earplugs and 6 months later noted wrist and arm problems.

The wrong hearing protection can The wrong hearing protection can be worse than none at all…be worse than none at all…

No hearing protection 103 dB SPL

“Industrial” protection 113 dB SPL

ER-25

(proper protection)

104 dB SPL

The wrong hearing protection can be The wrong hearing protection can be worse than none at all…worse than none at all…

With the ER-25, wrist and arm strain was reduced

EMG activity returned to normal

Improved monitoring was the key

A Study of Conventional Earplugs A Study of Conventional Earplugs with Brass Musicians with Brass Musicians (Smith and Thelin, 2003)(Smith and Thelin, 2003)

With conventional foam earplugs, the playing level of brass players increased by 2.2 dB.

– Decreased monitoring ability– Decreased sound quality because of high-

frequency loss.

Acoustic MonitorAcoustic Monitor

Useful for bass string instruments such as the cello and acoustic bass.

Four feet of #13 hearing aid tubing with an adaptor. One end plugs in to the left Vented/tuned earplug and the other is inserted in the “ƒ”-hole of the cello or bass.

Similar to an acoustic stethoscope

(only less than $10 in parts!)

Acoustic MonitorAcoustic Monitor

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Bass ShakersBass Shakers

BafflesBaffles

Baffles have limited usefulness unless they are within 7 inches of the ear with optimal attenuations being 15-17 dB in the higher frequencies.

(Camp and Horstman, 1992)

Attenuation from BafflesAttenuation from Baffles

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In-The-Ear MonitorsIn-The-Ear Monitors

These are either:

Custom (Futuresonics, Sensaphonics, Westone, Ultimate Ear …)

Or

Non-custom (ER-4, ER-6, Shure, Sennheiser …)

In-The-Ear Monitors (in situ)In-The-Ear Monitors (in situ)

In-The-Ear Monitors In-The-Ear Monitors (transceiver)(transceiver)

Transceivers:– Sennheiser– Shure

Intensity vs. LoudnessIntensity vs. Loudness

Our role as hearing health care professionals is to “delude” the musician into thinking that the music is sufficiently loud, but at a lower intensity level.

The Zen Of Hearing Loss PreventionThe Zen Of Hearing Loss Prevention

“Maintenance of loudness with reduction of intensity”

The Mantra….The Mantra….

Improved monitoring

- Bass increase

- Shakers (ultra-low frequency woofers)

- In-the-ear monitors

- Acoustic monitors

The Big Four …The Big Four …

Moderation

Humming

Improved monitoring

Environmental strategies

Four Expedient Environmental Four Expedient Environmental

Techniques to Reduce Noise/Music Techniques to Reduce Noise/Music

ExposureExposure

1. Speaker/amplifier combinations 1. Speaker/amplifier combinations should be elevated from the floor.should be elevated from the floor.

Energy Loss with Loudspeaker in Energy Loss with Loudspeaker in Contact with FloorContact with Floor

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2. Strings should always have at 2. Strings should always have at least two meters of unobstructed least two meters of unobstructed space above them.space above them.

High Frequency Loss with a Poorly High Frequency Loss with a Poorly Constructed Pit OverhangConstructed Pit Overhang

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3. Two meters of unobstructed floor 3. Two meters of unobstructed floor space in front of the orchestra.space in front of the orchestra.

Two Meters of Unobstructed Floor Two Meters of Unobstructed Floor Space in Front of OrchestraSpace in Front of Orchestra

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4. Treble brass instruments should be 4. Treble brass instruments should be on risers.on risers.

Loss of Energy for Higher Loss of Energy for Higher Frequencies at –45 Degrees Frequencies at –45 Degrees

(low [red], mid [yellow] and high [green] frequency)(low [red], mid [yellow] and high [green] frequency)

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Why do you instantly dislike Why do you instantly dislike trumpet players?trumpet players?

Because it saves time…Because it saves time…

Marshall.Chasin@rogers.comMarshall.Chasin@rogers.com

www.musiciansclinics.comwww.musiciansclinics.com