AlarmsoundsbasedonHumanFactors

NatashaBarrett

HFCWEBseminar,oktober 2021

AlarmsoundsforEquinor's Hywind Tampen controlroom.

Challengesandsolutionsarerelevanttodifferentsituations.

Background:

Problemswithtoday'scommonalarms:

Thesounds:• Unpleasantaurally• Unpleasantexperientially• Canbetooloud• Canbetoostartling• Couldbemoreinformative

Theresult:• Silencethealarmassoonaspossible

• Disturbancetocommunication

• Workfatigue

• (Mutingthecompletealarmsystem!)

• (Addingpersonalsounds!)

Whatshouldalarmsbelike?• Indicatewhatresponseisrequiredwithoutthenegativeeffectsofcurrentalarmssounds.

• Beeasytounderstand.

• Unique

• Bedesignedinkeepingwiththecontrol/notificationsystem(whichinturnshouldconsiderhumanlimitations).

Whatelsecouldalarmsdo?• Indicatewhichconsoleissoundinginamulti-consoleenvironment

• Providemoreinformationaboutthetypeorclassofalarm.

Newalarmsounds:Function|Sound-design|Acoustics|Workenvironment|Perception

Pastwork:Patterson(1982)

MostofthepastworkinalarmsoundbuildsonideaspublishedbyRoyPattersonin1982:

• Aburstofsoundwithitsownsetoffrequenciesintherange150–3000HzatadBlevel.

• Arepeatedpatternofsound-pausedurations

• Differentlevelsofpriorityareindicatedbychangesinthesound-pausepattern

• Subsequentvariationsonthisideahaveaddedpitch/notepatternstothesound-pausepattern.

Thesesolutionsneglectsomeobviousproblems:Soundswerechosento'cutthrough'noisyenvironments:

Backgroundnoisehasdecreased.

Thesuggestedfrequenciesarelocatedinourmostsensitivehearingrange.

• Toavoidconfusinglevelsofurgency,fastnotesequencesareneeded.Thesecreatestress.

• Development:notesequencesareshowntocreateconfusionratherthanaddclarity.

• Alackofdesigncompoundsnegativefactorsconcerninguninterestingsounds.

Pastwork:Alarmsand'earcons'• Soundsthatmayrangefromrepresentational(resemblingreal-worldsounds)to

abstract(puretones,buzzersorinstrumentalsounds).

• Theideaisthatthereissomeidentifiablecontentthatovercomestheproblemsassociatedwithlearningthemeaningofsingletones.

• Experimentalworkonrepresentationalsounds:lessappropriateintheworkplace.• Toostrange• Experiencedasannoying• Spectrally(frequencycontent)notclearenough

SpecificationfromEquinor• ’Alarm’sounddesigntosignaldifferencelevelsofpriority• ‘Earcons’sounddesignasindicationsounds.

‘Alarms’and'earcons'?

Theideaof‘earcons’isobsoleteifweinsteadassumethatouralarmsovercomestheproblemsassociated

withlearningthemeaningofsingletones.

Alarmsandnotifications

Basicdesignconsiderations

Environment:• Backgroundnoisesand

othersounds.• Peopleinteraction.• Peoplelocation.• Acoustics.• Loudspeakerlocations.

Perceptionandaction:• Audibility.• Identity.• Affect.• Repetition.• Redundancy.• Interaction(silencing

alarm).

Designprocess

Moveawayfrom:

• Extremedifferencesinpatternspeedreflectingurgency.

• Attackingthemostsensitivefrequencyareaofourhearing.

• Simple/boringnotesequences.

Insteadask:

• Whatkindofsoundsweareusedtohearing?

• Whatkindofsoundswecanacceptasalarmsounds?

• Howwouldthedifferentsoundsfittogetherasaset?

• Howtooptimisethevolumeandspectrumonsitebysimplecalibration?

• Urgency/priorityasrelativeratherthanabsolute(i.e.onlyarchetypessuchasfirealarmbellsandthelikeshouldbeabsolute).

Choiceofsoundtypes

• Acousticsourcesandtheirtransformations(identity/uniqueness).• Synthesisedsources(identity/genre).• Pitchrangesandspectraldistribution.

Transformation

Digitalsignalprocessingacoustic synthetic

Morphology,identityandinterestAmplitude

Spectrum

attack

decay

sustainrelease at

tack Therest..

Firstsetofsounds• Aselectionofacousticsoundstransformedwithdigitalsignalprocessing.

• Aselectionofsynthesisedsoundstransformedwithdigitalsignalprocessing.

• Importanceofcontrast(evenifitwasexpectedthatsoundsoundswouldappeartoostrangeformostlisteners).

examples

Testingstage1:privatetestingonmyself• Environmentalemulation

• Loudspeakerthatwillbeusedinthecontrolroom

• Combinations/permutations

• Repetitionandpatterns

Result:shortlist

Testingstage2:Testset-up• Testingwithreallistenersinaworkenvironment:four/fivepeopleondifferentshifts.

• Howto'rate'thealarms?statisticalapproachese.g.pairwisecomparisonsareproblematicwithoutalargenumberoflistenersandspecialBayesianapproachestotestfor‘self-contradictions’.

• Asklistenerstoexplainwhytheylikedonesoundmorethananotherusingtheirownwords.

• UseadBmetertoensureanapproximatelycorrectlisteninglevel.

ResultsListenercomments:

• Likeordislikeofwhatalistenerassociatedthesoundwith.• Suggestionofthesound'simpliedpriority.• Descriptionofhowstressful/relaxedthesoundfelt.• Descriptionofpartsofthesoundthatwerelikedordisliked(andwhatitmadethe

listenerfeel).• Whetherthesoundwassimplypleasanttohear,irritating,orunpleasant.• Howwellthesoundcontrastedorfittedwiththeothersoundsintheworkplace.

Results• Less‘real-world’soundsweremoresuccessful.• Thefollowingsimpleradjustmentschangedtheresults:• Listeningvolume:morphologyallowedreducedvolume.• EQ(spectralbrightness):tunedforthespeakersandacoustic.• Repetitionspeedimplyingurgencyanditsconnectiontostress.

Secondtestset• Reducedlistofsounds.

• Newresults:somecontradictiontothefirstresultsforthesamesoundpresentedinanewwaytothesamelisteners.

• Sound-pausesequenceswherenotonlyabouturgency,butabout‘sustainability’.

• Smallchangesindurationandmorphologywereimportant:i.e.playthedurationthatisneededtocommunicatethemessage.

Finalsetoffoursounds

Futurepotential

Sharedcontrolroomswithuniquealarms.

Acontrolstationaudiofingerprint.

Alarmscouldsoundsimultaneouslyandnotleadtoconfusionorstress.