A Critical Review of Current Practices and Outcomes In Recreational Noise-Induced Hearing Loss Studies

KAMAKSHI GOPAL

UNIVERSITY OF NORTH TEXAS

DENTON, TEXAS, USA

Outline

• Introduction

• Overview of current practices

• Summary of study outcomes

• Need for a universal protocol

Introduction

• The objective of this presentation is to summarize the methods adopted and results obtained by various investigators in the area of recreational noise-induced hearing loss. The purpose is to provide an opportunity to recognize the commonalities and inconsistencies among these studies.

• During this discussion, noise-induced hearing loss from recreational or environmental noise in non-occupational situations will be referred to as recreational noise-induced hearing loss (RNHIL).

• Under this the following settings/contexts were considered appropriate: bars, nightclubs, pubs, concerts, discos, sports arenas, noisy sports, hobbies, personal audio systems, theaters, urban transportation systems, etc.

Current perspectives

• A review of literature indicates that for more than 40 years studies have attempted to identify and quantify the effects of recreational noise exposure on hearing and auditory-related symptoms.

• Comparison of results across research studies has been a challenge because of varied samples, methods and protocols.

• Individual susceptibility to noise is a major factor (Biassoni and Serra et al. 2005), and must be recognized as we discuss variability between studies and samples.

• However, even with varied methods, it must be acknowledged that the data obtained thus far supports the risk posed by recreational noise on the human auditory system.

• Most studies point to the fact that excessive exposure to loud recreational noise does impact hearing ability, and can lead to other auditory-related symptoms such as tinnitus, difficulty understanding speech and hyperacusis.

Sample studies that reported Temporary or Persistent Tinnitus and Temporary or Permanent Threshold Shifts

Category Author(s) Temporary Tinnitus Persistent Tinnitus Temporary Hearing

Threshold Shift (TTS) Permanent Hearing

Threshold Shift (PTS)

Concerts/Bars/ Recreational Studies

Bogoch et al. (2005) 26 to 50% 76 to 100% 76 to 100% 26 to 50%

Jokitulppo et al. (2005) 51 to 75% 0 to 25%

Percent of Participant Results or Reports of target symptom in

article

Muhr & Rosenhall (2010) 0 to 25% 0 to 25% 0 to 25%

Derebery et al. (2012) 0 to 25% 51 to 75%

Gilles et al. (2012) 76 to 100% 0 to 25% 51 to 75%

Gilles et al. (2013) 51 to 75% 0 to 25% 26 to 50% 0 to 25%

Tung & Chao (2013) 0 to 25% 26 to 50%

Degeest et al. (2014) 51 to 75% 0 to 25% 51 to 75%

Balanay & Kearney (2015) 0 to 25% 0 to 25%

76 to 100%

Gan et al. (2016) 26 to 50%

Degeest et al. (2017) 51 to 75%

PAS Studies Williams (2005) 0 to 25% 0 to 25% 0 to 25%

Bulbul et al. (2009) Group 1 - 26 to 50% Group 1 - 26 to 50%

Group 2 - 26 to 50% Group 2 - 0 to 25%

Group 3 - 0 to 25% Group 3 - 26 to 50%

Fontana Zocoli et al. (2009) 51 to 75%

McNeill et al. (2010) 26 to 50%

Figueiredo et al. (2011) MP3 Users: 26 to 50%

Non-users: 0 to 25%

Danhauer et al. (2012) 76 to 100% 0 to 25%

Oghu et al. (2012) 0 to 25%

Sulaiman et al. (2014) 26 to 50%

Keppler et al. (2015) 76 to 100% 26 to 50%

Silvestre et al. (2015) 0 to 25%

Sulaiman et al. (2015)

Le Prell (2011)

PAS users: 0 to 25%

PAS users: 0 to 25%

Sporting Event Studies Swanepoel et al. (2010) 51 to 75%

Adams et al. (2016) TTS >10 dB: 26 to 50%

TTS >15 dB: 0 to 25%

Review

• For today’s discussion, research findings from 74 studies (from online databases) under the general topic of ‘RNIHL’ will be deliberated within the contexts of concerts/bars, personal listening devices (iPods, MP3 players) and sporting events.

These studies were numbered 1 thru 74

The next set of slides will summarize information from various studies under the topics of:

• Inclusion criteria – context/subjects

• Testing methods

• Test environment

• Key findings from audiometric tests and questionnaires

Inclusion criteria

1. For inclusion in this literature review, studies that addressed exposure to recreational noise and its effects on the auditory system in the context of (a) bars/concerts/clubs, (b) personal audio systems (PAS), or (c) sports arenas were included.

2. Cross-sectional as well as longitudinal studies were included.

3. Studies that used control groups (non-exposed participants), or those that compared pre-versus post-exposure data from the same set of subjects were included.

Sampling and Subjects

Sampling: Targeted approach was used most of the time (i.e., concert goers, PAS users), but questionnaires included volunteers.

Number of subjects: A wide range was found, questionnaires had numbers in thousands, experimental as few as two.

Subject age ranges: The subjects varied in age, ranging from pre-teens to older adults, but most were teenagers and young adults.

Exposure: Varied settings for the non-PAS studies.

Inclusion criteria: Some included only normal hearing subjects in their study, others did not specify.

Criteria for shift

Criteria for TTS: Any significant shift was accounted for in most studies, but some specified a minimum amount of shift, for example, 10 dB HL shift.

Post-exposure testing timing: Usually within 15-30 min of post exposure.

Follow-up after identifying TTS: Some reported testing subjects 16 hours after exposure, others waited 24 hrs.

Intervention: Only a few studies compared findings with and without interventional strategies such as the use of earplugs and antioxidants.

Methodology

1. Some studies relied on only self-reported questionnaires to capture awareness, and depth of knowledge among people regarding RNIHL.

2. Others obtained quantitative/experimental data in laboratory settings, clinical settings or venue settings using audiological equipment, dosimeter, etc. Some used combined approaches in their studies.

3. Most studies measured temporary changes in pure tone thresholds and/or Otoacoustic emissions, some looked at permanent changes.

Test Battery

Otoscopy: Almost all experimental studies reported performing otoscopy

Audiological Tests: Most included air conduction pure tone audiometry – usually between 500 to 8000 Hz, some combined it with one or more of the following:

(a) Extended high frequency audiometry (between 10 – 20 k Hz)

(b) Otoacoustic emissions – most often DPOAE, some had TEOAE with or without DPOAEs

(c) Immittance audiometry – tympanograms and reflex thresholds

Concert/Bar Studies PAS Studies

Sampling Volunteers (1,2,6,15,20, 25,32,29)

Targeted (3,4,5,7,8, 9, 10,11,12, 17, 18, 22, 23, 24, 30,31)

Volunteers (35, 36,42,45,46,47,49,50,53,55,57,60, 61,64,68)

Targeted (34,39,40,41,43,44,50, 52,54,56,58, 59,62,

63,65, 69, 70)

# subjects >8 (12,13,14,18,22,24,28,30)

>100 (9, 10, 16,17,19,23,25,31,32)

>1000 (11,21)

>2000 (6,15, 20,27)

>5000 (29)

>10 (34,35,38,41,28,52,56,59,65,68)

>100 (36, 39,42,43,44,45,49,51,54, 55,57,58, 60, 61, 62,63)

>1000 (40,50,53,64)

>2000 (47)

Inclusion Criteria

Normal hearing with or without tymps and ART testing (2, 9, 10, 21)

Normal hearing with or without tymps and ART testing (38)

PAS usage for at least a year at 50% volume (59)

TTS Criteria Any shift (most studies)

10 dB shift (4)

Any shift (most studies)

10 dB shift (none)

Subjects Concert/Bar Studies PAS Studies

Pre-teen (15)

Teenager

(2,9,10,16,18,20, 22,23) (43,44,47,50,52,53,54,62,64)

Young adults

(1,19,21,25, 28,30) (34,35,36,38, 39,40,45,46,49,55,57, 58,59, 60,61,63,65, 69, 70)

Young & middle age 16-59 yrs

(3, 4,7,11,13,15,17)

(51)

Young to elderly

(8) (68)

Middle age and elderly 48-92

(6)

(51, 68)

Military Recruits

(11,17)

(none)

Exposure Rock and other concerts (1,3,4,18,28, 32)

Music vs non-music noise exposure (2)

Music majors (24,30,31)

Rock concert – 4 types (8)

Subgroups-disco/rock concert/PAS (5)

Leisure activities (6,11,17,21,22,23)

Exercise +/- loud music (7)

Rec noise + PAS (16)

Leisure activity and heart disease (29)

Intervention

Antioxidants with no alcohol (12)

Earplugs (13)

Concert/Bar Studies

Concert/Bar Studies PAS Studies

Otoscopy Most often reported Most often reported

Questionnaires

General 1, 4,5,6,8,9,10, 16,17,18,19,25 34,35,39,40,42,45,53,54,55,56,57, 60,61,62,63,64,65, 69, 70

Validated - 20*,27*,32* 43*,47*,60*,61*,50**,52***,49^,20^^,32^^

Other 9, 10, 22,23 59

75% Return Rate 8,11,13

Tympanometry 36,39,43,47, 50, 69, 70

Pure-tone Audiometry

Standard Frequencies (.5, 1, 2, 3, 4, 6, and 8 kHz)

1,2,3, 4,5,7, 9, 10,11,13,14,16,17,18, 21, 22,24,27,32

36, 38,39,43,44,59, 60,61,65,69,70

Air and bone 6

Extended High freq 10-20 kHz 9,10, 36,59,62,63, 65,69,70

OAEs DP (7,12,18,25, TEOAE (23,24,25) DPOAE (38,39,60,61,64) TEOAE (49,60,61)

Dosimetry 3,4,9,10,12,13,14,18,24,28 56

Focus group interview 41,52

Real Ear/KEMAR 9,10 33,35,38,40

Youth Attitudes Towards Noise Scale (YANS)(*), National Health and Nutrition Examination Survey (NHANES)(**), and The Listening Habits questionnaire (***), Tinnitus Handicap Inventory (THI) (^), Beliefs about Hearing Protection and Hearing Loss (BAHPHL) (^^)

Testing Environments

Concert/Bar Studies PAS Studies

Clinical sound-booth 2,3, 5, 7,11,17,21,24 36,43,44, 47,49, 50,60,61,62,63,65, 69, 70

Mobile vans with booth

12, 13,15,16,17,18,22

Quiet room in building 4,6,18,19, 21

Concert/Bar Studies

PAS Studies

Control Group 1,5, 12, 24, 25 36,39,59

Cross-Sectional 1, 2, 3, 4, 11,23,24,25,27,29

38,39,44,46,47,49,50,51,52,57,59,60,61,62, 63,64,65, 69, 70

Longitudinal 9 (4 yrs), 10, 22 (3 yrs)

Dosimeter Findings

>85dBA weekly exposure 11,12,13,18, 28 51, 53, 65

>100 dbA for 4.5 hrs 3, 9,13

>118 peak 13

Peak=140 dBA, > 2-4 daily dose

4

< OSHA/NIOSH (or other limits in music practice)

14,28

>OSHA/NIOSH 4,12,24,28,30,31 56, 66,69

Follow-up 4 36

Concert/Bar Studies PAS Studies

PTS Findings

Teenage boys had higher exposure levels and increased thresholds at 4&6k Hz in four years

9

Moderate recreation activity led to less threshold shift (tough vs. tender ears)

10

20% prevalence of hearing loss 11

21% of teenagers had hearing loss (mild to mod) which was sig related to recreational noise exposure

16

14.5% prevalence of hearing impairment 17

11.9% participants had threshold greater than 25 dB at least one frequency

21

34% had unilateral or bilateral hearing loss. Patients with CHD were 1.91 times more like to have bilateral HF hearing loss than normal hearing participants

29

12/55 reported significant hearing loss 34

3 to 8 k Hz and high frequency audiometry more sensitive 36

Hearing loss prevalence increase from 14.9% to 19.5% between 1988-1994

47

MP3 users:8k Hz thresholds significantly higher and TEOAE reduced at 2k Hz

49

DPOAE showed no significant results among groups 64

Concert/Bar Studies PAS Studies

OAE Findings

No shift in DP with/without PAS & exercise

7

DP decrease of 5 dB, mostly at 3 kHz. No change with antioxidant

12

Significant DP decrease (18, 25 at 1.5 kHz) and TEOAE decrease

22, 23,25 (at 1&4 kHz),

Significant absence of DPs between music & non-music majors

30

Significant reduction of DPs/TEOAEs within 1.5 to 6 kHz, with no shift in pure tone threshold

38

. . . and with decreased pure tones thresholds

39, 65

OAE more sensitive 38,39

DPOAE alone not an adequate predictor of RNIHL

64

Sporting Events – Findings

• Stadiums where ambient noise levels were studied using dosimetric measurements, and included arenas where professional hockey and soccer, as well as collegiate basketball and hockey were played (71,72,73,74)

• Subjects were young to middle age adults, and number of subjects included ranged from 2-23.

• Average exposure as recorded from the dosimetric measurements indicated 103 dBA, which would be way over the daily allowance without ear protection for the professional hockey game (71), 101 dBA average for soccer with peaks of 140 dBA (72,) average at basketball game was 135 dBA

• General findings using pure tone audiometry and OAEs indicated a decline (TTS) in pure tone thresholds by 5-10 dB at most frequencies, with the biggest decline of 20 dB at 4 k Hz (71, 73,74), 3.4 dB at 2 k Hz (72, 74),

2 dB SPL for DPOAEs (72, 73) .

• Tinnitus was a common finding.

Overview of RESULTS - Concert/Bar Studies – Significant or Nonsignificant^ TTS & other symptoms

500, 1, 2, 3, 4 kHz PTS, TTS, 1, 14,18

4-6 kHz (Non-musical noise worse) - TTS 2

4 k worst - TTS 3, 4,12, 24

Significant PTS shift in PAS users of 7hrs/wk > rock concerts twice/month. No shift in disco 5

Hearing loss or shift in thresholds in subjects engaged in loud leisure activity 6,11,17,22,23

No shift with PAS 95 dB SPL for 20 min, with or without exercising 7

Hearing loss in 15-20% young military recruits, 67% tinnitus, 27% were exposed to leisure noise 11,17

TTS of 7.6 dB HL in control group and antioxidant (N-acetylcysteine) group 12

Less occurrence of TTS with earplugs 13

More than 50% had threshold shift or DP decrease post-concert that averaged 99 dBA 18

Longitudinal three-year study indicated significant increase in thresholds 22

Transient tinnitus in 13 to 74%, 4 to7% chronic tinnitus in regular concert goers 25

Ear pain in 23 % 27

Hyperacusis/ear sensitivity in 21% 27

Significant TTS differences , ^ not significant threshold differences in music & non-music majors

24, 30

People with bilateral hearing loss are 1.91 more likely to have coronary heart disease than their normal hearing counterparts

29

Overview of PAS Studies – Significant or Nonsignificant^ Temporary Threshold Shift (TTS) & Tinnitus

500 to 8 k Hz and extended high frequencies if PAS used over a long period 36,39,66, 69, 70

Worse thresholds for conventional & high frequency, poor word discrimination if >80dBA use

65

^ No significant threshold shift in PAS users if < 80 dBA 34,

^ No significant TTS from PAS in lab for 30 min at 85 dBC, but decrease in OAE 38

8% teenagers that exhibited noise notch reported listening to PAS for 6-10 hrs daily 43

Although all had normal hearing, males had higher thresholds, especially at 4 k Hz 44

Prevalence of hg loss in teenagers was 1/3 higher in 2005-2006 compared to 1988-1994, especially in 3-8 k Hz, which was attributed to loud noise exposure For the same data set, with a different criterion (not using 8k), no difference was found between data sets.

47, 50

Higher incidence of tinnitus in regular PAS users 49, 55,59,61,63,66

. . .with higher thresholds 61

. . .specifically at 8k 49

. . . at 2 k and 9 thru 16 kHz 59,63

Worse hearing thresholds in older teenagers compared to younger teenagers, attributed to longer years of PAS usage

62

Concert/Bar Studies - Questionnaire findings

• 60% participants-too loud/intolerable (4) • Auditory suffering (tin/fatigue) in PAS, rock, disco (5) • Leisure activity auditory symptoms, tinnitus 23% and hyperacusis 16% (17) • Out of 204, 73 % said music concerts were loud, 80% did not use protection, 85% had tinnitus,

38% had hearing disturbances, 40% willing to use protection if free (8) • 2500 respondents on 73-item questionnaire (15)- only 32% considered hearing loss as a problem • 2/3 were aware of MIHL, 1/2 experienced some ear problem –tinnitus, hearing loss, pain 15% used earplugs • 145 respondents (19) – About 90% reported temporary tinnitus. More females then males, also

louder tinnitus among females. 2/3 reported decreased hearing ability following loud music, only 11% used hearing protection

• 3991 respondents (20) 75% reported temporary tinnitus, with increase in age. 18% reported permanent tinnitus, 39% experienced hearing loss sometimes, 11% experienced more often. 4% used hearing protection.

• 1787 participants (21), 81% attended at least one loud activity in a year, 91% listen to PASs, 12% had hearing loss at least one ear/one frequency.

• Longitudinal study (22) indicated increased music exposure levels as teenagers grew older with increased thresholds and TEOAEs

• Cross sectional study (32) showed that highest noise exposure was from movies/plays, followed by nightclubs and music concerts. Age was associated with hearing loss.

Key points from previous slide

• 60 to 70 % thought concerts were too loud

• 66% were aware of MIHL

• 38 to 66% reported having hearing disturbance

• Tinnitus reported in 50 to 90 %

• Taking listening breaks helped reduce symptoms

• 40% were willing to use ear protectors

• When earplugs were provided, only 11% chose to wore

PAS Studies - Questionnaire & Focus Group Interview Findings

• >40 % exceeded standards of daily dosage (35), 62% exceeded (57), 58% exceeded especially in noise (66/reviewed 26 articles)*. Attenuating background is the most effective way (66).

• >90% were aware of risk from loud noise (35, • <30% believed PASs qualified as a risk (35,54, • Hearing loss in 14% (36), 6-59% (66) of ears with long-term use of PAS . Even if thresholds were

normal, males had higher thresholds, especially at 4 k (43). Females showed more threshold shifts (50).

• Focus group interviews of adolescents showed more male PAS users at maximum levels. Subjects underestimated personal vulnerability to hearing loss from PASs, but willing to change if it was officially established that loud music causes hearing loss.

• Among students aged 11-18, an average of 88% reported listening to loud music, 26% reported hearing loss, and 25% reported tinnitus (42). Frequent tinnitus in 6%, with no concern of TTS (54). Among young adults > 90% had listened to PASs for 3-6 yrs, 21% reported tinnitus (55).

• Among teenagers, 71% reported daily/weekly use of PAS, 69% had tinnitus after exposure (43). Higher prevalence of loud music exposure thru headphones in 2005-6 compared to 1998-94 (50,

• Most college students listened to MP3 players for less than two hours/day at safe levels (45, 58,), but turned up the volume to full level at times (45). About 90% turned up their volume in the presence of loud background noise. More than 1/3 reported soreness and distraction while listening, 50% were concerned about hearing loss and were willing to reduce volume to conserve hearing (45). 90% did not exceed SCENIR daily recommendations (58)

Key points from previous slide

• 6 to 59 % of ears exhibited hearing loss, 25 to 69% reported tinnitus

• 40 to 60% exceeded daily dose, especially in NOISY BACKGROUND

• 90% college students were aware of risk from loud noise, but only 28% thought PASs were risky at loud levels

• 90% young adults had listened to loud music for more than 3 yrs

• Most teenagers were not aware of risk, but willing to change if risk was established

PAS Studies - Questionnaire & Focus Group Interview Findings (continued)

• Canadian study indicated UG students took responsibility for protecting hearing, median sound levels that they listened was between 67-79 dBA (46)

• No significant differences between PAS users in subway vs other modes of transportation, or between males and females (51)

• 90% of subjects report using PASs, 29% were at risk for hearing loss with estimated level of 89 dBA exposure in one hour (53). Most teenagers are not aware of hearing health and open to education (54)

• Based on correlates of PAS behavior and PMT (protection motivation theory), sociodemographic and psychological characteristics were identified in teenage PAS users– rewards from listening to high levels and high habit strength and not motivated to protect hearing were highly correlated (53)

• When self-reported data from young adults were compared to dosimeter data, their listening times, volume control level and noise doses were not significantly different (56)

• Ethnic background and age were significant factors, African Americans listeners and subjects 24 yrs and younger listened at higher levels (57)

• Participants with a positive attitude towards noise had increased threshold, lower OAEs and less hearing protection use than others (60)

• No correlation between audiological measures and type and degree of recreational noise expsosure (61)

Key points from previous slide

• Participants with positive attitude towards noise used less hearing protection, showed increased thresholds and lower OAEs

• Canadian UG students took responsibility for protecting hearing and listened to softer levels

PAS Studies – Study Recommendations

• Longitudinal studies are needed to accelerate use of hearing protection in youth using PASs (37, 61),

• Region/country-specific differences are present, so global hearing conservation programs were recommended (43)

• Organized public education on safety issues of PAS was recommended (45). PASs can reach 91-121 dBA levels and higher thresholds among PAS users (67). Education and regulation of PAS needed (53, 66, 67,)

• Due to the concern of PAS exposure in combination with recreational noise exposure in teenagers, a 50% noise dose was recommended (52)

• Increasing background noise attenuation in earphones can result in lower listening levels in PAS users (66). Younger adults listen at higher PAS values, and highest level noticed for digital multimedia broadcasting programs (68)

Need for a universal protocol

• Comparison of results across research studies has been a challenge because of varied sources, methods and protocols adopted by the researchers.

• Various exposure evaluations

• Some quantify the exposure

• Different tests/combination of tests

• Questionnaires, pure tone audiometry, OAEs, ABRs

• Different age groups

• WHO intends to come up with a universal protocol with standard methodology for various types of exposures, and field test the protocol

• Implementation of this protocol by researchers should enhance comparison of results across studies, and assess longitudinal changes within studies for tracking RNIHL over an extended period

Goal of future studies

• The objective of future studies must be defined so as to make the protocol robust enough for all applications intended

• Incidence

• Prevalence

• Longitudinal studies

• Evaluation of interventional strategies

• Incidence and prevalence studies must be designed carefully with appropriate questions that will consider other possible etiologies. For e.g. genetic non-congenital hearing loss, transient middle ear disorders, medications, other underlying medical conditions, etc.

Standards for testing • Inclusion and exclusion criteria must be applied consistently

• Thorough case history information must be solicited to rule out pre-existing temporary threshold shifts. Previous and immediately preceding exposure to loud occupational or non-occupational noise must be recorded prior to testing

• Hearing tests – behavioral and objective

• Details of frequency, stimuli, recording needed

• Calibrated equipment

• Sound-booth

• Otoscopy

• Tympanograms

• Instructions, test protocols and procedures

• Questionnaires – validated?

THANK YOU