1. 1 Saami Winter School Feb 10 Bodø, Norway David Nathan Endangered Languages Archive Hans Rausing Endangered Languages Project SOAS, University of London Audio Recording Techniques & Equipment

2. 2 Topics - session 1  Questions  Audio workflow  Evaluating recordings  Perception and psychacoustics  Microphones  Connections  Recorders  Carriers

3. 3 QUESTIONS

4. 4 Questions  You buy a recorder for $x. A matching microphone would cost: (a) 3x (b) 0.75x (c) 0.3x (d) 0.1x (e) none of these - cost is irrelevant

5. 5 Big questions  What are we actually recording?  What is it for?  What is the role of audio in language documentation?

6. 6 What is audio?  Audio is not data  real world  record phenomena  represent phenomena  derive data  Audio is a resource  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 neceessary to record well

7. 7 AUDIO WORKFLOW

8. 8 Audio workflow who/what/where /why/how do you want to record? contact people audio training equipment & budget assemble, test, practise Before you go

9. 9 Audio workflow transport safely check environment, situations, permissions make test recordings local training & collaboration On site, before recording

10. 10 Audio workflow record! monitor! collect metadata labelcheck quality monitor Sessions

11. 11 Audio workflow labelcheck quality backupadd information (transcriptions, annotations, metadata etc) After sessions

12. 12 Audio workflow send samples to archive add information (transcriptions, annotations, metadata etc)... package and send to archive Later

13. 13 EVALUATING RECORDINGS

14. 14 Evaluating recordings  signal  noise  signal to noise ratio  listenability (eg comfort, consistency)  fit for purpose

15. 15 Evaluating recordings  audio professionals use the human ear as evaluator of audio quality and value, while many linguists mistakenly look to formats, wave-forms, analyses etc  44.1 KHz, 24 bit

16. 16 Signal - what you want  content  contextual and spatial information  fidelity  comfortable to listen to

17. 17 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

18. 18 Noise - what you don’t want  generated by event (unwanted)  shuffling papers, clothes  table banging  backchannel from interviewer  equipment handling, especially microphones and cables

19. 19 Avoiding handling noise  use stands and cradles etc

20. 20 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

21. 21 Evaluating environment/situation external environment  access  electricity  external noise sources

22. 22 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

23. 23 Dead cat

24. 24 Close-up noise sources  machines examplepossibilities for dealing with it refrigeratorpre-survey what comes on intermittently turn off relocate motors, switchingmonitor fansmonitor, dead cat (windjammer)

25. 25 Dealing with noise sources  be prepared and aware  seek collaboration  monitor  use or modify room acoustics  location  direction  surfaces  reflection  absorption  isolation

26. 26 Room acoustics  location  away from doors, windows, traffic areas  direction  face away from noise sources  surfaces  avoid hard smooth surfaces  reflection  avoid parallel surfaces  absorption  choose or create soft or rough surfaces  isolation  find an ‘’airtight’’ place

27. 27 PERCEPTION & PSYCHOACOUSTICS

28. 28 Audio perception/psychoacoustics  audio information is diverse  a human listener has:  location and orientation in physical world  two ears - which are incredibly sensitive  a brain/mind  the mind merges and selects from various sources of audio information  listening is actually a “hallucination”  so what should we record?  typical recording methods are unscientific!

29. 29 Psychoacoustics and recording  microphones are not like camera lenses  they don’t have “edges”  don't distinguish wanted and unwanted info  the recording process removes some information

30. 30 Implications for recording  you need to set goals, plan and manage recording  goals  equipment  sources  environment  settings  example: recording spatial information  why is this important?

31. 31 “Sound stage”  spatial information is an essential part of audio  we are amazingly attuned to it  we should record in stereo

32. 32 “Sound stage” ... or in ORTF (binaural)

33. 33 MICROPHONES

34. 34 Microphones and audio quality  microphones are the greatest determinant of audio recording quality  selection of appropriate microphone(s) for the task  placement and handling of the microphone(s)

35. 35 Microphones in the digital era  microphones in the digital era  recorder quality has increased but prices decreased  microphones have become comparatively more expensive  why? microphones are analogue devices!

36. 36 Microphone types  principle: dynamic vs condenser  directionality: omni, cardoid, and shotgun  spatiality: mono, stereo, binaural

37. 37 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

38. 38 Microphone directionality - omni omni

39. 39 Omni  lavalier or tie-clip microphones are typically omni-directional

40. 40 Microphone directionality - cardioid cardioid

41. 41 Cardioid  many “standard” handheld microphones are cardioid units

42. 42 Microphone directionality - shotgun directional/shotgun/hypercardioid

43. 43 Shotgun  shotguns are good for quiet sources, in some noisy environments, and for video work

44. 44 Stereo microphones  spatial information is an essential part of audio

45. 45 Full “sound stage”: ORTF

46. 46 Simulating ORTF with 2 cardioids 17cm 110°

47. 47 Microphones - quality  generally, you get what you pay for  each model has its own subjective colour  decent microphones for language documentation fieldwork cost from £120 to £300

48. 48 Reputable makers - include  AKG  Audio Technica  Beyerdynamic  Røde  Sennheiser  Shure  Sony

49. 49 Microphone placement

50. 50 Microphone usage principles  where should the microphone be?  in general, about 20cm from the speaker’s mouth  the inverse square law is your friend...

51. 51 The inverse square law

52. 52 The inverse square law

53. 53 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

54. 54 CONNECTIONS

55. 55 Microphone connections  plugs  cable types  cables for stereo/mono, multiple  wireless  power sources for condenser microphones - battery or phantom power  see http://www.hrelp.org/archive/advice/microphones.html

56. 56 Microphone connections  minijack/miniplug (fragile)  RCA/phono  1/4 inch (headphone)  XLR (Canon)

57. 57 XLR  professionals always use them  electrical contact is independent of the physical connection  latching is independent of the electrical contact  you can use XML-to-miniplug cables or converters for recorders with miniplug inputs

58. 58 RECORDERS

59. 59 Recorders  types and their strengths/weaknesses/implications  quality parameters  accuracy (frequency response, distortion, s/n ratio)  reliability  features  versatility  power sources, battery type and battery life

60. 60 Recorders  media types, costs, properties, implications  connections  formats

61. 61 Using recorders  settings – levels, formats, AGC/ALC  a second recorder?  do you have to do it yourself?

62. 62 CARRIERS

63. 63 So you’ve recorded something?  carrier  types  to label... or not  preservation  track the content  you may need to digitise/redigitise/ capture it

64. 64 General guidelines for success  microphone choice  monitoring  familiarity and skill with equipment  power and batteries  a range of equipment, not the “perfect item”!  consistency principle  juxtapositions  efficient field sessions and later processing

65. 65 END OF AUDIO BASICS!

66. 66 PART 2: AUDIO PROPERTIES

67. 67 AUDIO SIGNALS

68. 68 Audio is initially analogue  analogue means an infinitely variable property of the real physical world  digital means a sequence of measurements of real world properties, ie symbols

69. 69 Audio signal parameters  pitch kHz - human voice  fundamental 100 (m) – 200 (f) Hz  formants 800 Hz – 4+ kHz  harmonics, other, up to 15 kHz  amplitude (power) dB  a relative and logarithmic measure  0 dB is reference point; sound of mosquito flying at 3m  max human is about 140 dB (pain = 120)  each 6 dB step perceived as doubling/halving volume

70. 70  signal to noise  ratio of wanted to unwanted sound data  the bigger the number the better Signal parameters

71. 71 DIGITAL AUDIO

72. 72 Digital audio AnalogueDigital (identify and measure points)

73. 73 Digital audio

74. 74 Digital audio parameters  digital means measuring or “sampling”  where and when is it done?  the properties of digital audio are:  sampling rate(Hz)  sample size (“resolution”, “bit depth”)  mono or stereo  for compressed data: bit rate (Kb/s)

75. 75 Digital audio parameters  what do these mean?  11KHz, 8 bit  44.1 KHz, 16 bit  48 KHz, 24 bit  192 KHz, 48 bit  these have implications for  quality  file size  compatibility, usage...

76. 76 Encoding  “codecs”  file formats eg WAV, AIFF, AU, MP3, Ogg

77. 77  reasons  types  open and proprietary formats (eg MP3 vs ATRAC)  lossy and non-lossy (most are lossy)  repeated compression unpredictable  distinguish sound information content from its encoding and its carrier Compression

78. 78 Digitising  where is it actually done?  involves either  digitisation (capturing/ingesting)  re-digitisation (capturing)  copying (may involve transcoding, e.g. ATRAC)

79. 79 Digitising  where was your audio digitised?

80. 80 Digitisation: results and quality  what does the result depend on?  player and digitising devices  settings  levels  cables, connections, environment

81. 81 Digitisation: results and quality  where can quality be lost?  (as well as original recording issues)  poor treatment of carriers  unknown properties of carriers (eg unlabeled)  choice of output port, settings (level, format etc)  choice of input port, settings etc  quality of player and digitising devices  connections/cables, interference from other devices or mains supply

82. 82 End