Encouraging Students Towards Meaningful Subjective Comparisons

encouraging students towards meaningful subjective comparisonsBradford SwansonJuly 27, 2013 - Murfreesboro, TNAES 50th Conference on Audio Education

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encouraging students TO:use their earsbeware of outside stimuliunderstand research methodsincorporate into daily practice

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outlineaudio research methodspractices in other disciplinessample comparison experienceaudio specific recommendations

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subjectivity research in audiocodecsup/downmixingmultichannel techniquesHRTF & spatial perception

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subjectivity research in audiographical representationscomparisons ratings

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sound qualityspeech intelligibility

localization & envelopment

audio research methods2:15 PM - CoE 164 - Paper #21“From Practice to Research and Back Again: Research Skills in Audio Engineering Education” Drs. Leffords & Berg

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audio research methodsITU-R BS.1116-1ITU-R BS.1534-1 ITU-R BS.1284-1semantic differential

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ITU-R BS.1116-1 (ABC/HR)

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Methods for the subjective assessment of small impairments in audio systems

Three stimuliRated by impairmentSingle listen to eachReference Reference = one of the stimuli

ITU-R BS.1534-1 (MUSHRA)

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Method for the subjective assessment of intermediate quality level of coding systems

MUltiple Stimulus with Hidden Reference and Anchor

Three or more stimuliRated by sound qualityMultiple listensReference Reference = one of the stimuliAnchor = one of the stimuli

ITU-R BS.1534-1 (MUSHRA)

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Method for the subjective assessment of intermediate quality level of coding systems

MUltipleStimulus

and

Anchor

HiddenReference

Source: mushraJS

ITU-R BS.1284-1 (general)

General Methods for the Subjective Assessment of Sound Quality

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Single stimuli

ITU-R BS.1284-1 (general)

General Methods for the Subjective Assessment of Sound Quality

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Multiple stimuli

semantic differential

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Source: Marui, A., Martens, W. - “Timbre of nonlinear distortion effects: Perception beyond aptitude beyond “sharpness”?”

ratings along bipolar adjective scales


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9 stimuli randomized through all 12 adjective pairs

Stimuli One

Dark ---------------------- Bright



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Stimuli Eight

Dark ---------------------- Bright




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Stimuli Eight

Sharp ---------------------- Dull




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Source: Marui, A., Martens, W. - “Timbre of nonlinear distortion effects: Perception beyond aptitude beyond “sharpness”?”

9 stimuli assessed using all 12

adjective pairings


practices in other disciplinesFormal Sensory Evaluation Psychological TendenciesCultural ConsiderationsCasual/Social Experiences

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sensory evaluation methodsAffective Tests

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“Untrained” ParticipantsQuantative Suvery QuestionairreQualitative Interview or focus group Free response description

sensory evaluation methodsDescriptive Analysis orAttribute Difference Tests

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Highly trained participantsSensory lexicon of defined termsRating intensity or quality on a scale

sensory evaluation methodsDiscrimination or Overall Difference Tests

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Highly trained participantsThree Stimuli (two similar)Whether there is a difference and/or

How much of a difference there is


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A - B - Awhich is the odd one out?


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A (ref.) - A - B or

B (ref.) - A - B

which is most/least like the reference?


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A (ref.) - A - B or

B (ref.) - A - B

how much difference is there between these samples?

psychological tendenciesExpectation ErrorsSuggestion EffectsDistraction ErrorsStimulus/Logical ErrorsHalo Effects/Proximity ErrorsCarry-over, Order or Contrast Effects

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cultural considerationsPersonal PreferencesBackground ExperienceAccessibility

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sensory evaluation methodsExperimental Design

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Identify test objectivesDetermine statistical analysis methodDefine the terminology usedProvide a controlConsider screening order

subjective listening experience15 examples Varying timbral qualitiesMark your perception

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SUBJECTIVE LISTENING EXPERIENCETest Objective

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develop critical listening skillscompare timbral perception of equipment

SUBJECTIVE LISTENING EXPERIENCEStatistical Analysis

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Not collected - for personal use

SUBJECTIVE LISTENING EXPERIENCEDefine the terminology

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Timbe:Content = ContentPresentation = PresentationPitch = PitchLoudness = LoudnessSomething = Something


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Timbe:Harmonic Content or Frequency Spectrum


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Timbe:Content = ContentPresentation = PresentationPitch = PitchLoudness = LoudnessSomething = Something

SUBJECTIVE LISTENING EXPERIENCEConsider Screening Order

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?

subjective listening experience15 examples Varying timbral qualitiesMark your perception

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subjective listening experience

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“uncolored”or

natural reproduction of the harmonic content of this voice


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“colored”or

significant deviations from the natural harmonic content of this voice


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colored uncolored

l------l------l------l------l------l


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what the heck was that?

SUBJECTIVE LISTENING EXPERIENCEConsider Screening Order

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RandomisationBalanced Test Design

*5 stimuli*each presented 3 times*in different orders


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What the heck was that?Shakespeare’s 29th SonnetPerformed onceBob Kuhn (bkvoice.com)5 microphones - 3 times eachReferences included as stimuliSimilar signal flow


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Colored referenceExamples 4, 8, and 15

Shure 55sw


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Examples 3, 9, and 14

Beyer M-88


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Sennheiser MD-409


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AKG C-535


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Uncolored referenceExamples 5, 11, and 13

DPA 4006


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1) MD-4092) C-5353) M-884) 55sw5) 40066) C-5357) MD-4098) 55sw

9) M-8810) MD-40911) 400612) C-53513) 400614) M-8815) 55sw

Casual/Social experiences

“it’s a wine-tasting,

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not a shootout” Tom Bates

recommendationsExperimental Design

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Define GoalsDefine VariablesMinimize Distractors

recommendationsMatching non-variables

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PerformancePresentationSignal PathGain

recommendationsListening Experience Design

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Listening EnvironmentsDouble-Blind TestingConduct a pilot sessionListen past the technology

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Encouraging Students Towards Meaningful Subjective Comparisons

Technology

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