The Musical The Musical Videoconference Videoconference Audio Quality Audio Quality vs. vs. Echo Cancellation Echo Cancellation Dr. Brian K. Shepard Dr. Brian K. Shepard Coordinator of Music Technology Programs Coordinator of Music Technology Programs University of Oklahoma School of Music University of Oklahoma School of Music
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The Musical Videoconference Audio Quality vs. Echo Cancellation Dr. Brian K. Shepard Coordinator of Music Technology Programs University of Oklahoma School.
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The Musical VideoconferenceThe Musical Videoconference
Audio QualityAudio Qualityvs.vs.
Echo CancellationEcho Cancellation
Dr. Brian K. ShepardDr. Brian K. ShepardCoordinator of Music Technology ProgramsCoordinator of Music Technology Programs
University of Oklahoma School of MusicUniversity of Oklahoma School of Music
• Ribbon - Ribbon - rather fragile, warm sounding, works with rather fragile, warm sounding, works with fairly low sound levelsfairly low sound levels
• Condenser - Condenser - fairly sturdy, bright and crisp fairly sturdy, bright and crisp sounding (accurate), will work with extremely low sounding (accurate), will work with extremely low sound levelssound levels
The Omnidirectional Microphone hears in a 360º sphereThe Omnidirectional Microphone hears in a 360º spherearound the diaphragm.around the diaphragm.
DiaphragmDiaphragm
Figure-8 MicrophoneFigure-8 Microphone
The “Figure-8” or Bidirectional Microphone hears inThe “Figure-8” or Bidirectional Microphone hears infront of and behind the diaphragm.front of and behind the diaphragm.
Cardioid MicrophoneCardioid Microphone
The Cardioid Pattern Microphone hears predominantlyThe Cardioid Pattern Microphone hears predominantlyin front of the diaphragmin front of the diaphragm
Supercardioid MicrophoneSupercardioid Microphone
The Supercardioid Pattern Microphone hears mostly inThe Supercardioid Pattern Microphone hears mostly infront of the diaphragm, but has a small rear pickup lobe.front of the diaphragm, but has a small rear pickup lobe.
Hypercardioid MicrophoneHypercardioid Microphone
The Hypercardioid Pattern Microphone hears mostly in front of the The Hypercardioid Pattern Microphone hears mostly in front of the diaphragm, but with a larger rear lobe and very little side pickup.diaphragm, but with a larger rear lobe and very little side pickup.
Boundary MicrophoneBoundary Microphone
Because the Boundary Microphone is placed on a flat surface, it Because the Boundary Microphone is placed on a flat surface, it hears above and beside the diaphragm in a half-spherical pattern.hears above and beside the diaphragm in a half-spherical pattern.
Dynamic, CardioidDynamic, CardioidPattern MicrophonesPattern Microphonesplaced close to theplaced close to the
performerperformer
Speakers positionedSpeakers positionedbehind, and off-axisbehind, and off-axisto the Microphonesto the Microphones
Non-Reflective Surface behind the PerformerNon-Reflective Surface behind the Performer
ElectronicElectronicGadgetsGadgets
Echo-CancellationEcho-CancellationModulesModules
Using Compression to “Duck”Using Compression to “Duck”Speaker LevelsSpeaker Levels
• Insert a “Sidechain” Compressor on Speaker Insert a “Sidechain” Compressor on Speaker ChannelsChannels
• Set Sidechain “Key” input to the signal from the local Set Sidechain “Key” input to the signal from the local microphone(s)microphone(s)
Using Compression to “Duck”Using Compression to “Duck”Speaker Levels (cont.)Speaker Levels (cont.)
• Threshold: Set so the local person’s level is above Threshold: Set so the local person’s level is above the threshold, while the remote level is below.the threshold, while the remote level is below.
• Ratio: Try between 5:1 and 7:1Ratio: Try between 5:1 and 7:1• Attack: Try between 100 to 250 msAttack: Try between 100 to 250 ms• Release: Try between 500 to 1000 msRelease: Try between 500 to 1000 ms• Makeup Gain: Set at 0 dBMakeup Gain: Set at 0 dB
Compressor DetailCompressor Detail
Using Gates or Expanders to Using Gates or Expanders to Silence MicrophonesSilence Microphones
• Insert a Gate or Expander on each Microphone Insert a Gate or Expander on each Microphone ChannelChannel
• Gates turn off the channel, while Expanders turn Gates turn off the channel, while Expanders turn down the channel. Thus, Expanders are usually down the channel. Thus, Expanders are usually more graceful than Gates.more graceful than Gates.
Using Gates or Expanders to Using Gates or Expanders to Silence Microphones (cont.)Silence Microphones (cont.)
• Threshold: Set so that the local person’s softest level Threshold: Set so that the local person’s softest level is above the threshold.is above the threshold.
• Ratio (Expander): Set below 1:1, Try 0.5:1Ratio (Expander): Set below 1:1, Try 0.5:1• Attack: Try between 2 to 10 msAttack: Try between 2 to 10 ms• Release: Try between 50 to 200 msRelease: Try between 50 to 200 ms• Makeup Gain (Expander): Set at 0 dBMakeup Gain (Expander): Set at 0 dB
Gate DetailGate Detail
Expander DetailExpander Detail
Using a Limiter to ControlUsing a Limiter to ControlAudio Pops and “Hits”Audio Pops and “Hits”
• Insert a Compressor/Limiter on Speaker ChannelsInsert a Compressor/Limiter on Speaker Channels• Threshold: Set just above highest sound levelThreshold: Set just above highest sound level• Ratio: Set to 20:1 or greaterRatio: Set to 20:1 or greater• Attack: Set as short as possibleAttack: Set as short as possible• Makeup Gain: Set to 0Makeup Gain: Set to 0
Limiter DetailLimiter Detail
For More InformationFor More InformationDr. Brian K. ShepardDr. Brian K. Shepard
Coordinator of Music Technology ProgramsCoordinator of Music Technology Programs
OU School of MusicOU School of Music
500 West Boyd Street, Room 138500 West Boyd Street, Room 138