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1 LingDy 12 Feb 2013 TUFS, Tokyo David Nathan Endangered Languages Archive Hans Rausing Endangered Languages Project SOAS, University of London Audio theory and practice for language documentation
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2 Questions have you recorded audio? have you published audio? what else have you done with your audio?
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3 Question digitally recorded audio is better quality than analogue recorded audio because: (a) digital microphones are more accurate (b) digital formats are more accurate (c) digital equipment is newer (d) digital formats capture more information (e) no, digital audio is not better than analogue audio
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4 Big questions what are we actually recording? what/who is it for? what is the role of audio in language documentation?
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5 An epistemology for audio in documentation an audio recording is made in order to be experienced by a human listener a recording conveys what a human listener would experience at a particular location in an event setting documentation goals define recording methodology a recording should capture spatial information metadata about the recording and the recording setting are required for full interpretation ethical recording respects speakers and honours their contribution through your effort and skill
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6 Evaluating recordings accuracy: how well is the signal captured, as true to its sources and without distortion? intelligibility/information accessibility: can the desired content be identified? signal vs. noise: is the ratio acceptable? can the focal source be separated from all sources of noise? listenability/comfort/aesthetics: is it easy on the ears? will it be comfortable to listen to for an extended time?
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7 Evaluating recordings localisation of sources: is enough spatial information captured? separation of noise: can all sources of noise be separated? representation of environment: are the acoustic properties of the recording space appropriately represented?
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8 Evaluating recordings content (identity, performance, uniqueness, coverage): were the right people recorded doing the right things? editability/repurposeability: is the recording suitable for turning to relevant purposes?
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9 Recording audio making it is both art and science a critical and ethical responsibility strongest relationship to communities it’s not necessary to record everything, but it is necessary to record well
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10 SIGNAL & NOISE
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11 Evaluating recordings signal noise signal to noise ratio listenability (eg comfort, consistency) fit for purpose
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12 Evaluating recordings audio professionals use their human ears as evaluator of audio quality and value, while many linguists (mistakenly?) look to formats, spectrographs, wave-forms, analyses etc 44.1 KHz, 24 bit
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13 Signal - what you want content contextual and spatial information fidelity comfortable to listen to
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14 Noise - what you don’t want from environment: near: people, animals, activities far: traffic, generators, planes machines: refrigerators, fans, computers not hearable: mobile phones, electrical interference acoustic: reflections/resonance
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15 Noise - what you don’t want generated by (unwanted parts of) event shuffling papers, clothes table banging backchannel from interviewer equipment handling, especially microphones and cables (and recorders with built-in mics)
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16 Avoiding handling noise use stands and cradles etc
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17 Noise - what you don’t want generated by equipment wrong input levels circuity noise (cheap or incompatible) compression loss or distortion ALC/AGC effects (pumping) video camera motors
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18 External noise sources examplepossibilities for dealing with it trafficinvestigate, record in quiet time face away use damping materials childrenget them involved show something to satisfy curiosity animalschoose time of day weather (wind, thunder, rain etc) use dead cat; wait; reschedule see also General principles
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19 Dead cat
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20 Close-up noise sources machines examplepossibilities for dealing with it refrigeratorpre-survey what comes on intermittently turn off relocate motors, switchingmonitor fansmonitor, dead cat (windshield)
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21 Dealing with noise sources be prepared and aware seek collaboration monitor use or modify room acoustics location direction surfaces reflection absorption isolation
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22 Utilising room acoustics location away from doors, windows, traffic areas direction face away from noise sources reflection avoid parallel surfaces surfaces avoid hard smooth surfaces choose or create soft or rough surfaces isolation find an ‘’airtight’’ place
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23 When is a noise not a noise? When it is part of the content, for some interpretation of the event John Cage performance Available on iTunesAvailable on iTunes (150 yen)
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24 PERCEPTION & PSYCHOACOUSTICS
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25 Audio perception/psychoacoustics a human listener has: location, orientation in a physical setting two ears - incredibly sensitive a brain/mind the mind selects from various sources of sound and other sensory information, using long- and short-term memory listening is actually a “hallucination”
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26 Psychoacoustics and recording microphones don’t have a mind: they can't distinguish wanted from unwanted sound microphones don’t have “edges” like camera lenses
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27 Psychoacoustics and recording the recording process loses acoustic information if you only care about transcription, then you are going to throw away over 99% of the acoustic information anyway! real world record acoustic phenomena represent (some) linguistic components derive data
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28 Implications for recording typical recording methods are unscientific! … so what should we do?
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29 Implications for recording plan and manage recording goals equipment preparation and settings other preparation environment and setup sources changes, actions, settings
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30 Implications for recording why is it important to record spatial information? what other information (acoustic or non- acoustic) do we need?
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31 “Sound stage” spatial information is an essential part of audio we are amazingly attuned to it we should record in stereo
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32 “Sound stage” ... or in ORTF (binaural)
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33 MICROPHONES
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34 Microphones and audio quality microphones are the greatest factor in audio recording quality selection of appropriate microphone(s) for the task placement and handling
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35 Microphone types principle: dynamic vs condenser directionality: omni, cardoid, and shotgun spatiality: mono, stereo, ORTF, binaural
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36 Microphone physical principles dynamic generate signal from sound pressure more robust, less accurate used for musical and live performance condenser more fragile, sensitive and accurate need power source - battery or phantom power in general, use condenser microphones for language documentation
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37 Omni lavalier or tie-clip microphones are typically omni-directional
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38 Microphone directionality - omni omni-directional
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39 Cardioid many “standard” handheld microphones are cardioid units
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40 Microphone directionality - cardioid cardioid
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41 Shotgun shotguns are good for quiet sources, in some noisy environments, and for video work
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42 Microphone directionality - shotgun shotgun/directional/hypercardioid
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43 Stereo microphones spatial information is an essential part of audio
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44 Full “sound stage”: ORTF now the “best practice” for field recordings” (Austrian Academy of Science, Vienna Phonogrammarchiv) Superlux S502 Full binaural on dummy head
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45 Simulating ORTF with 2 cardioids 17cm 110°
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46 Microphones - quality generally, you get what you pay for each model has its own subjective “colour” good microphones for language documentation cost from $180 to $500
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47 Reputable makers - examples AKG Audio Technica Beyerdynamic Røde Sennheiser Shure Sony
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48 Microphone placement
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49 Microphone usage principles where should the microphone be? in general, about 20cm from the speaker’s mouth the inverse square law is your friend...
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50 The inverse square law
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51 Using the inverse square law if you have noise sources, maximise the signal to noise ratio by: placing the microphone as close as possible to the signal source placing the microphone as far as possible from the noise source
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52 AUDIO WORKFLOW
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53 Audio workflow who/what/where /why/how do you want to record? contact people audio training budget, research, and buy equipment assemble, test, practise Before you go
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54 Audio workflow transport safely check environment, situations, permissions make test recordings local training & collaboration On site, before recording
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55 Audio workflow record! monitor! collect metadata check quality monitor Sessions select equipment (microphones)
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56 Audio workflow (label)check quality backupadd information (metadata, metadocumentation, transcriptions, annotations, etc) After sessions
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57 Audio workflow add information (metadata, metadocumentation, transcriptions, annotations, etc) package and send to archive Later other audio outcomes and resources
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58 End
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