digital jumpstart workshops: audioidrh.ku.edu/sites/idrh.drupal.ku.edu/files/files/... · exercise:...

11

Arienne M. Dwyer

University of Kansas

Digital Jumpstart

Workshops:

Audio

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What weWhat we’’ll coverll cover

�� Part 1: The Audio Signal and PreservationPart 1: The Audio Signal and Preservation

�� Part 2: Audio CapturePart 2: Audio Capture

�� Part 3: Basic editingPart 3: Basic editing

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What makes a good recording?What makes a good recording?

�� LetLet’’s listen to a couple of s listen to a couple of

recordings...recordings...–– Which is better, and why?Which is better, and why?

�� LetLet’’s listen once just to the audio, thens listen once just to the audio, then

�� LetLet’’s listen and look at the wave formss listen and look at the wave forms

Sample 1Sample 1 Sample 2Sample 2

Part 1: The Audio SignalPart 1: The Audio Signal

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Comparing the previous two...Comparing the previous two...


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Quality considerationsQuality considerations

�� During recording: (1) level (sampling rate)During recording: (1) level (sampling rate)

(2) Minimizing noise (ambient & machine) (2) Minimizing noise (ambient & machine)

�� During capture: Sampling rate & Compression During capture: Sampling rate & Compression –– Sampling rate (kHz + channels + bits (per second, per channel)) Sampling rate (kHz + channels + bits (per second, per channel))

–– Compression: more or less Compression: more or less ““lossylossy””

–– Compression formats (e.g. Compression formats (e.g. mp2mp2, , mp3mp3, ., .oggogg, .wma), .wma)

�� ““LosslessLossless”” formats (BIG!) for archiving, editing, hiformats (BIG!) for archiving, editing, hi--fi playback : mp4fi playback : mp4--als, als, Apple+ Win LosslessApple+ Win Lossless

�� ““LossyLossy”” formats (SMALL!) for online streaming, formats (SMALL!) for online streaming, terrterr. radio: .mp3, .. radio: .mp3, .rmarma

�� Bottom line: Bottom line: SampSamp= = usually/at leastusually/at least 44.1 kHz, Comp= 44.1 kHz, Comp= ““less less lossylossy””–– Lossless or less Lossless or less lossylossy formats: .formats: .aiffaiff (Mac), .wav (PC)(Mac), .wav (PC)


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Open AudacityOpen Audacity

(Audacity is free audio editing software)(Audacity is free audio editing software)

�� Open the sample audio file (...mp3)Open the sample audio file (...mp3)

�� What is the sampling rate?What is the sampling rate?

�� How many channels (stereo or mono)?How many channels (stereo or mono)?

�� Is this a Is this a lossylossy or lossless format?or lossless format?

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Workflow 1Workflow 1

�� Recording Recording –– what your device can handlewhat your device can handle

–– Sound frequencies in kHz (kilohertz)Sound frequencies in kHz (kilohertz)

–– 44.1 kHz or higher for linguistic/musical work44.1 kHz or higher for linguistic/musical work

–– (22 kHz (22 kHz -- ok for some work) ok for some work)

�� Capture Capture –– data transfer to computerdata transfer to computer

–– Memory cards (> USB) > computerMemory cards (> USB) > computer

–– If your device is not digital If your device is not digital –– conversion from conversion from

analog to digital, then captureanalog to digital, then capture


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Workflow 2: formats/tasksWorkflow 2: formats/tasks

�� Working Working –– highhigh-- or average quality formator average quality format

�� Archiving Archiving –– uncompressed formatsuncompressed formats

–– Uncompressed/less compressed Uncompressed/less compressed formats bestformats best

–– Allows repurposing in futureAllows repurposing in future

�� Presentation (web, CD, etc) Presentation (web, CD, etc)

–– CompressedCompressed formats often betterformats often better

–– Faster downloads, take less space Faster downloads, take less space


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Devices and CompressionDevices and Compression

�� Strongly recommended: lossless digitalStrongly recommended: lossless digital–– solidsolid--state recorder (CF/SD) state recorder (CF/SD)

–– Archive Formats: .wav, Archive Formats: .wav, aiffaiff, (.au) , (.au)

�� Not recommended: MP3 recorders, Not recommended: MP3 recorders, dictaphonesdictaphones, cassette recorders, cassette recorders

(may be ok for non(may be ok for non--archival quality archival quality interviews)interviews)

�� Switch default settings from mp3 (usually Switch default settings from mp3 (usually 32 kHz) to 44.1 kHz 32 kHz) to 44.1 kHz -- newer newer iPodsiPods, others, others


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(A note on analog recordings)(A note on analog recordings)

�� We all have analog cassette recordingsWe all have analog cassette recordings

�� If you have them, preserve them If you have them, preserve them asapasap! ! ((egeg in in CtrCtr for for DIgitalDIgital Scholarship)Scholarship)

�� These are fine: These are fine:

–– as as ““heritage/legacyheritage/legacy”” materialsmaterials

–– if you donif you don’’t have access to a digital devicet have access to a digital device

�� But for future recordings, ideally, weBut for future recordings, ideally, we’’d d

recommend recommend digital recording in 44.1 kHz digital recording in 44.1 kHz .wav format.wav format

Part 2: Audio CapturePart 2: Audio Capture

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Audio EditingAudio Editing

�� Keep a pristine (unchanged) Keep a pristine (unchanged) originaloriginal version version

–– LOCKSS (lots of copies keeps stuff safe)LOCKSS (lots of copies keeps stuff safe)

–– You or others may want to go back to the original You or others may want to go back to the original

�� First, First, savesave a copy with a new namea copy with a new name

–– Rename the file with a unique, concise, and Rename the file with a unique, concise, and

explanatory label explanatory label

–– develop your own system; recommend is date, develop your own system; recommend is date, lglg

code etc.code etc.

Part 3: Basic editingPart 3: Basic editing

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�� Playing, Selecting, Cutting, and PastingPlaying, Selecting, Cutting, and Pasting–– To chop one file into two sessionsTo chop one file into two sessions

–– To excerpt a portion (segment/clause/utterance) for To excerpt a portion (segment/clause/utterance) for presentationpresentation

�� Exercise: cut a portion out of your recording and Exercise: cut a portion out of your recording and save it as a new file save it as a new file –– play this file play this file –– Icons or Shortcuts: Icons or Shortcuts: CntrlCntrl--X [ct] or X [ct] or CnutrlCnutrl--C [copy] C [copy]

–– FileFile--New, New, CntrlCntrl--V [paste] V [paste] ---- then then save under a new save under a new namename

–– Other: Other: CntrlCntrl--tt [Trim, removes material [Trim, removes material outside outside the the selection], selection], Undo, Undo, Trim Silence selection (e.g. to Trim Silence selection (e.g. to remove a long pause or goat noises from recordingremove a long pause or goat noises from recording


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Navigating in AudacityNavigating in Audacity

�� Shortcut: [spacebar]=play Shortcut: [spacebar]=play

�� Zooming in and outZooming in and out–– use the (+/use the (+/--) magnifying icons) magnifying icons

–– Can zoom whole recording or a portionCan zoom whole recording or a portion

–– Helps find boundaries to select and/or cutHelps find boundaries to select and/or cut

�� Practice Practice ““loopinglooping”” a sounda sound–– Helps us find boundaries + do transcriptionsHelps us find boundaries + do transcriptions

–– With the mouse, select part of the recordingWith the mouse, select part of the recording

–– Press Shift + play Press Shift + play buttonbutton


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Exercise: Audio editingExercise: Audio editing

�� From your recording, chop the following:From your recording, chop the following:

–– Two whole utterancesTwo whole utterances

–– Any two words from these utterancesAny two words from these utterances

–– Any two sounds Any two sounds

�� Sometimes this process can be Sometimes this process can be

automated, if there are pauses between automated, if there are pauses between

items (e.g. word lists, musical pieces)items (e.g. word lists, musical pieces)


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Types of Software Types of Software

Consider: Consider: Proprietary Proprietary ($$, code is business secret) ($$, code is business secret) vs. vs. nonnon--proprietaryproprietary (usually free, open (usually free, open source); platformsource); platform

�� Audio editingAudio editing

�� Audio analysisAudio analysis–– Acoustic (e.g. phonetic) analysis Acoustic (e.g. phonetic) analysis -- Spectrogram, f0, Spectrogram, f0,

intensityintensity

–– TimeTime--linking + annotation (audio only) linking + annotation (audio only)

–– TimeTime--linking + annotation (audio + video)linking + annotation (audio + video)


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I have a bad recording... I have a bad recording...

�� Too quiet (levels too low) Too quiet (levels too low) –– hard to hearhard to hear

�� Too loud Too loud –– ““clippingclipping”” (seen here)(seen here)


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More advanced Signal processingMore advanced Signal processing

�� Noise removal (see next slide)Noise removal (see next slide)

�� Conversion wav to mp3 (Conversion wav to mp3 (““LameLame”” plugplug--in)in)

http://http://audacity.sourceforge.net/help/faq?saudacity.sourceforge.net/help/faq?s==ii

nstall&itemnstall&item=lame=lame--mp3mp3

�� AmplifyingAmplifying

�� Concealing identityConcealing identity

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Enhancement Enhancement

�� First: Save file under a different name!First: Save file under a different name!

�� Extraneous noise: delete (Extraneous noise: delete (CntrlCntrl--X) or X) or

insert silence (insert silence (CntrlCntrl--L) L)

�� Enhancing lowEnhancing low--volume digital recordings volume digital recordings

–– maximize signalmaximize signal--toto--noise ratio noise ratio

(wanted/unwanted sound data)(wanted/unwanted sound data)

�� Analyze Analyze –– Silence Finder Silence Finder –– Export Labels Export Labels

(silences)(silences)


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RecapRecap

�� Audio signalAudio signal

–– Record and archive at highest possible quality; Record and archive at highest possible quality;

–– Share in compressed formats (for Share in compressed formats (for egeg internet)internet)

�� Audio captureAudio capture

–– Transfer without (further) lossTransfer without (further) loss

–– Archive in a nonArchive in a non--lossylossy format (never mp3)format (never mp3)

�� Audio editingAudio editing

–– ALWAYS first save ALWAYS first save and archiveand archive a copy that is a copy that is

unenhancedunenhanced, lossless, and stored in a non, lossless, and stored in a non--proporietaryproporietary

format (or quasiformat (or quasi--open such as .wav or .ale)open such as .wav or .ale)

–– LOCKSS (LOCKSS (LLots of ots of CCopies opies KKeeps eeps SStuff tuff SSafe)afe)

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