Acoustic Trauma: Minimum Exposures to Continuous Noise...TTS experiments had no PTS after more...
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2/20/19 1 Acoustic Trauma: Minimum Exposures to Continuous Noise Robert A Dobie Elliott H Berger NHCA; Grapevine TX, Feb 8, 2019 How it started • Berger: Single MRI session (even w/HPDs) can lead to minimal TTS (ABR; Jin et al 2018); can we predict risk of PTS using ISO 1999? • Dobie: let’s look at Dix Ward’s (1991) paper • Berger: why don’t you update Ward’s analysis of acoustic trauma and present this at NHCA? • Dobie: why don’t you? • Berger: let’s do it together. Annals of Surgery, 1945 Definitions
Transcript of Acoustic Trauma: Minimum Exposures to Continuous Noise...TTS experiments had no PTS after more...
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AcousticTrauma:MinimumExposurestoContinuousNoise
RobertADobieElliottHBerger
NHCA;GrapevineTX,Feb8,2019
Howitstarted
• Berger:SingleMRIsession(evenw/HPDs)canleadtominimalTTS(ABR;Jinetal2018);canwepredictriskofPTSusingISO1999?
• Dobie:let’slookatDixWard’s(1991)paper• Berger:whydon’tyouupdateWard’sanalysisofacoustictraumaandpresentthisatNHCA?
• Dobie:whydon’tyou?• Berger:let’sdoittogether.
AnnalsofSurgery,1945
Definitions
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AcousticTrauma• Olderauthors(and,sadly,evensomeofourcontemporarycolleagues):anyhearingchangecausedbynoise(temporary orpermanent,acuteorchronic)
• Currentusage:“asuddenchangeinhearingasaresultofasingleexposureto… sound”(ACOEM,1989,2002,2012)(Chadwick,Hinchcliffe,andGlorigpapersinOccupationalHearingLoss,ed.Robinson,1971)(Sataloff&Michael,HearingConservation,1973)
• OurreviewislimitedtopuretonePTSfromcontinuousnoise
Acoustictraumavs.“acousticshock”
• Recentpapers(Westcott2006;Hooper2014;Baguley etal2016)suggestthatsuddenunexpectedsoundsthatdon’tcausePTSareassociatedwith– Hyperacusis– Otalgia– Tinnitus– Dizziness– Sleepdisturbance
• MostlyfromclustersofcallcenteremployeesinAustralia,Denmark,andGB(socialcontagion?)
• Briefsounds,levels≥82dBA(McFerran &Baguley 2007)• Nodocumentedobjectivefindings
Ward1991;“HearingLossfromNoiseandMusic”PresentedatAudioEngineeringSociety.
“Bob–Itsurewouldbenicetobeabletoaddtothissparsecollectionofpoints,butsofewpeoplehavetheforesighttogetanaudiogrambeforeacoustictrauma.- Dix”
Ourgoalwastodojustthat.
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Methods• Searchforpaperswithexposures(level,duration)andaudiometricevidenceofPTS(presentatleastoneweeklater)
• Sources:Ward1991references,RADandEHBownfiles(>6000PDFseach),otherref.lists
• PubMed(Human,English)– “acoustictrauma”OR(hearinglossAND(noiseORmusic)AND(suddenORacute))
– 577hits,only11metcriteriabasedontitle,abstract• Included19reMRI(nonedocumentingacoustictrauma)
Methods(cont.)
• AlsosearchedDefenseTechnicalInformationCenter,andqueried47colleagues
• Only9papersreportedacoustictraumawithexposuredataandaudiometry– 3fromWard1991review– 2fromPubMedsearch– 3fromauthors’files– 1fromreferencelistofpaperfromauthors’files
• PubMedmissedmostofthe9
9informativepapersDavisetal.1950 TTSexperimentLenarz &Gulzow 1983 AcousticreflextestArriaga&Luxford 1993 “Hunteretal.1999 “Elonka 1986 “Orchik etal.1987 CordlessphoneSingletonetal.1984 “Kung&Sataloff2006 SirenMcMillan&Kileny 1994 Bicyclehorn
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Methods(cont.)
• Convertedlevelstoequivalentdiffusefieldlevels(dBA)forcomparabilitytoOSHA,NIOSH,etc.(methodsonrequest;wehopetopublish)
• Ambiguities– Durationssometimeshadtobeestimated– Offendingtone(reflextests)unclear;
chosetonewithhighestdBAlevel– Somelevelmeasurementmethodsunclear– Manyofourcaseslackedpeerreview
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Tentativelevels/durationscapableofcausingacoustictraumainmostsusceptible
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MRIexposures,LAeq andduration(highkurtosis)
Caveats
• Casereportsareanecdotal• Lowestlevelofmedicalevidence(belowrandomizedtrials,cohort,case-control,cross-sectional,caseseries)
• Specialcaseof“publicationbias”(resultscan’tberegardedastypical)
• Acoustictraumacasesmayrepresenttinyfractionofpopulation(mostsusceptible)
IntenseexposureswithnoPTS:4experiments(89Ss)andanaccident
(somehadverylargeTTS)
• Davisetal1950(n=19)• Eldredetal1955(n=10)• Schori 1976(n=40)• Brownson 1973(n=20)• Raleighetal1963(n=2,aftersteamlinerupture)
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jetenginenoise
CONCLUSIONS
• “Acoustictrauma”(AT)meanspermanentthresholdshiftafterasingleexposure,tobedistinguishedfromoccupationalNIHLandso-called“acousticshock”
• ATcanoccurinfewsecondsatlevels>130dBA,orafter10secondsatlevels>120dBA(ignoringoneoutlier)
• LackofATdoesnotmean“safe”(neuropathy?)• Acousticreflexcaseshadsignificantpriorhearingloss(whichiswhytheyrequiredsuchhighlevels)
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CONCLUSIONS(cont.)
• ATexposureswereatypicalofindustrialnoise(tonalornarrow-band,probablymorehazardousdB-for-dBthanbroad-bandnoise)
• ReportedATcasesprobablyrepresentmostsusceptiblefractionofpopulation(89subjectsinTTSexperimentshadnoPTSaftermoresevereexposures)
• AllreportedATexposuresexceededOSHAlimits;ATisunlikelytooccurincompliantprogramsorafterMRIwithhearingprotection
Acknowledgment
• ChristianGiguere consultedremethodsofestimatingdiffusefieldlevelsfromHLs,couplerlevels,andmannequinlevels
• BillClarkconsultedrehistoricalliteratureinthefieldsofTTSandacoustictrauma
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HypotheticaldistributionofTTS2 aftersingleintensebriefexposure
051015253545
RaresubjectwithTTS2 of50to60dB,thenPTS(acoustictrauma)?
051015253545
1in1000withPTS
