1 / 74

Audio Recording And Production: An Introduction

Audio Recording And Production: An Introduction Soam Acharya CS 731 Spring 1998 Contents sound basics acoustics/psycho-acoustics actual recording process Characterizing Sound Frequency and Pitch Amplitude and Loudness Frequency and Loudness Acoustic Phase Timbre Frequency And Pitch

Leo
Download Presentation

Audio Recording And Production: An Introduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Audio Recording And Production: An Introduction Soam Acharya CS 731 Spring 1998

  2. Contents • sound basics • acoustics/psycho-acoustics • actual recording process

  3. Characterizing Sound • Frequency and Pitch • Amplitude and Loudness • Frequency and Loudness • Acoustic Phase • Timbre

  4. Frequency And Pitch • 20 - 16000 Hz • “feel” outside this range • low bass: 20 - 80 Hz • traffic, thunder, explosions • upper bass: 80 - 320 Hz • fullness/boomy • rhythm instruments: drums, bass, low piano • midrange: 320 - 2560 Hz • fundamental of most sound sources • intensity • upper midrange: 2560 - 5120 Hz • highest sensitivity • treble: 5120 - 20000 Hz • brilliance/sparkle

  5. Amplitude and Loudness • db-SPL = 20 * log10 (sound pressure/ref. sound pressure) • can hear loudness at 1 - 10000000 or greater • the db type measurement also used frequently elsewhere

  6. Airport runway, inside a bass drum Threshold of pain: thunder, “in your face” vocals subway 1” away from acoustic guitar Average conversation Subdued conversation Furnished living room 120 100 80 20 40 140 60 Threshold of hearing 0 Amplitude and Loudness II dB-SPL

  7. Frequency and Loudness [p23 - fig 2-7] (in)equal loudness principle masking equalization

  8. Timbre Tone quality or color

  9. Timbre II Shape of sound or envelope

  10. Acoustics/Psycho-acoustics • direct waves • early reflection • later reflection (reverberation) • body • decay or reverberation time • echo • long reflection path

  11. Sound In An Enclosed Room P35 - 3-2

  12. Reverberation Vs. Decay Time Decay Time Concert hall gymnasium Conference room living room w. rugs Inside a car closet Tiled bathroom Open field Reverberation

  13. Surface Shape of Room Concave: concentrate Concave: disperse Parallel: standing waves

  14. Studio Room Surface P42 - 3-10

  15. Studio Room Materials • Sound absorption coefficient • 0 reflects, 1 absorbs • drapes > glass • porous absorbers • acoustical tiles, carpets, fibreglass, urethane foams • bass taps (diaphragmatic absorbers) • wood panels mounted over air space

  16. Sound to electric signal Analog processing/mixing Computer analog to digital storage digital to analog Processing/editing Actual Recording Process playback

  17. Converting Sound to Electricity: Microphones • moving coil • diaphragm, magnet, coil in a magnetic field • robust, not sensitive to transients, less expensive • ribbon microphone • metal ribbon in a magnetic field • printed ribbon • more robust design • good high frequency response • low output level ie. not sensitive

  18. spacer Back plate Air film Diaphragm - front plate Capacitor/Condenser Microphone • Needs separate power supply for pre-amp • electret type: pre-charged, can get away with batteries • professional use • high sensitivity, output level (large SNR)

  19. Microphone Pickup Patterns • Omnidirectional • all over • non directional • Bidirectional • front and rear • Unidirectional • front only • cardioid • unidirectional

  20. Pickup Patterns II

  21. Pickup Patterns III P 76 - 5-10

  22. Reading A Microphone Spec. Cardioid polar response diagram

  23. Reading a Microphone Spec II Frequency response plot

  24. 1/4” from mic 2” from mic frequency Proximity Effect of Mic. Relative level (dB)

  25. Microphone Accessories I windscreen Pop-screen

  26. Microphone Accessories II XLR -male XLR-female 3.5 “ (miniplug) RCA 1/4”

  27. Specialty Microphones • lavalier • shotgun • parabolic • wireless

  28. Lavalier Microphones • To be worn on lapels • omnidirectional • built-in high freq. boost (chin cutoff)

  29. Wireless Microphones • FM transmitter • UHF/VHF FCC approved • multiple modes

  30. Shotgun Microphones • Long distance pickup • need for unobtrusiveness on sets • attenuate sound from all angles except a narrow one in the front • supercardioid/hypercardioid/ultracardioid • less directional at lower freq.s

  31. Parabolic Microphones • Also long-distance pickup • omni/uni directional microphone

  32. Deploying Microphones • Acoustic/electrical phases • omnidirectional vs. unidirectional • miking speech for radio • miking speech for tv • recording music • reducing unwanted sounds

  33. Acoustic/Electrical Phases • Acoustic phases cancellation • 3:1 rule for microphones • dist between two microphones >= dist between source and main microphone P 292 12-1

  34. Omni vs. Uni directional • Omni • does not have to be held directly in front • picks up more ambience • less susceptible to wind, popping • more resilient to distance • Uni • cuts down unwanted sound • no sense of environment • reduces feedback in reverberant locations

  35. Miking Speech in Radio • Stay within pickup pattern • mic-to-source distance • inverse square law • proximity • weak voice • lip smacking • diffusion of sound quality

  36. Across directional mic face reduces freq. response 45 deg. angle Miking Speech in Radio II P 297 12-5 P297 - 12-6

  37. Stereo Miking • Two microphones • difference in arrival time between microphones • phase problems when combining to mono • Coincident miking • two directional microphones together on same vertical axis • minimize disparity in arrival times

  38. Stereo Miking II P 304, 12-13

  39. Miking for TV • News and interviews • Panel and talk programs • miking the audience

  40. News and Interviews • Omnidirectional lavalier • hide under clothes • rustling/movment • inhibits higher frequencies

  41. Panel and Talk Programs • Host/guest: • Lavalier microphones • unobtrusive • easy to mount • mic-source constant • Mobile host • handheld • pop filter/ shock mount • host can control source distance • go to audience

  42. Miking Audience • Directional shotgun microphones • distribute them in equal quadrants above the audience • audience monitor loudspeaker feedback • offaxis to microphones

  43. Recording Music • Distant miking • ensemble, reduces electronic noise • air loss with distance: freq dependent • phase • close miking • control • better separation of sources

  44. Recording Music II • Miking instruments • drums • bass drum: coil • damping • hi-hat: capacitor • violin/viola • multiple microphones to capture the range • vocals • proximity effect • sibilance • compression

  45. Putting It Together P 409 - 14-67

  46. Reducing Noise • Microphone location • near noisy sources • outdoor location: • noise suppressors (eq dialogue) • shielding • noise gates

  47. Roadmap Sound to electric signal Analog processing/mixing Computer analog to digital storage digital to analog Processing/editing

  48. Analog Processing/Mixing

  49. Analog Processing/Mixing II • Input: • overload indicator • trim • phantom power • equalizer/filter • phase reversal • panning • bus assignment (input signals to output buses) • cuing (for auditioning) • meters • mute

  50. Analog Processing/Mixing III • Output: • buses (to group signals) • bus fader • effects modules • output meter

More Related