RTV 497 / THE 530Sound and Audio
Sound in an environment
• Sound wave– Compression / rarefaction
• Frequency / Measured in hertz• Amplitude / Measured in decibels (db-spl)
– AM/FM, kHz / MHz (r.f.) • Attack/sustain (internal dynamics)/decay -- sound
envelope• Acoustics / Psychoacoustics / binaural hearing• Absorbed / Reflected• Direct / Indirect (echo & reverberation)
Some issues with sound• Equal loudness principle--depending on loudness
we don’t hear low and high frequencies as well as we hear middle
• Masking--Hiding of some sounds by other sounds by other sounds when each is a different frequency and they are presented together. Loud over soft / lower-pitched over higher
• Acoustical phase--the time relationship between two or more sound waves at a given point in their cycles
• Timbre--a sound’s unique tone quality or tone color
Production Room Sound Design
• Ergonomics – human element in designing room• Sound Absorption and Reflection• Diffusion--scattering of sound waves• Diffraction--spreading or bending• Resonance--vibration of an object at the same
frequency as the original body’s frequency• Lively or Dead Room• Isolation
Why Important?
• Equipment does not exactly re-create realistic, ‘natural’ sound
• You have to compensate
• Hidden close mic
• ADR / looping
• Recording voice track without ambient sound
• Record interviews w/o ambient sound
Sound Frequency Spectrum
• Bass– Low bass, 1st & 2nd octaves, 16-64 Hz– Upper bass, 3rd& 4th octaves, 64-256 Hz
• Midrange– 5th, 6th & 7th octaves, 256 - 2,048 Hz– Upper midrange: 8th octave, 2,048 - 4,096 Hz
• Treble– 9th & 10th octaves, 4,096 - 16,384 Hz
Digital Recording
• Sampling: takes periodic samples (snapshots, voltages) of the analog signal and converts that information into digital data
• Sampling frequency: the rate at which the signal is sampled: 44.1 kHz, 48 kHz
• Think of film at 24 fps – each still frame is a ‘sample’ (snapshot) of information in 1/24 of a second
Digital Recording• Quantization: how many ones and zeroes to
represent each sample• A quantity expressed as a binary number is called
a digital word.• 10 is a 2-bit word, 101 is a 3-bit, 1010 is a 4-bit
etc.• The greater the number of the quantizing level
(10010110 an 8 bit vs. 10, a 2 bit) the more accurate the representation of the analog signal.
Mics -- Review Sound
• Sound Frequency Spectrum– Bass, midrange, treble
• Frequency / Hertz• Amplitude / decibels• Acoustics• Direct / indirect sound
– Echo / reverberations
Microphone Directional Patterns• Omnidirectional / nondirectional
• Unidirectional / Directional/ cardioid– Super, hyper, ultra
• Bidirectional
• (see reading for diagrams)
Cardioid range
• Cardioid
• Supercardioid
• Hypercardioid
• Compare to parabolic
Professional Mic types
• Moving coil/dynamic
• Ribbon
• Capacitor/condensor
• Transducer – changes energy from one form to another – in this case sound waves into an electrical current
More about mics and sound
• Common analog audio connectors– RCA (phono), ¼” (phone), mini-plug, XLR– Jack (‘female’) vs. plug (‘male’)
• Close vs. distant miking– Cross-pair, mid-side as some distant miking approaches
• Wide – range of frequencies• Flat – accurately recreates frequencies• Colored response – changes frequencies (lavaliere
boosts high frequencies, for example
Common mic types
• lavaliere
• headset
• handheld
• studio/boom mounted, TV boom– Perambulator boom, giraffes, fishpole
• PZM (boundary mic)
Audio Mixing Equipment
• Three things you mix– Sources, techniques, aesthetics
• Audio console or DAW• ProTools or Adobe Audition• 5 console functions
– Amplify, switch, route, mix, balance
• Various console inputs• Routing: patch panel
Other console terms• Program / Audition• Monitor vs. cue• Master pot• VU meter / PPM (analog / LED)• Muting system• Foldback (IFB note)• Pad / trim / gain / AGC• Pan Pot• Submixer & pre-amp
Other audio mixing terms
• Compressor
• Limiter
• Equalizer (EQ)
• Filters– High pass, low pass, band pass, notch
• Stereo vs. multi-track recording– Basics of multi-track / mixdown
Three things you mix...
• Music– Production library, royalty-free loops– BMI, ASCAP, SESAC– blanket license vs. ‘needle drop’– SoundExchange fees
• SFX -- Production library, Foley• Voice
– Narration vs. dialogue– Walla difference
Audio layering
• Initially recording ‘clean’ / dry sound.• No flubs in narration.• No distracting sound bite content.• Multitrack / mixdown• You must view and set audio levels• You must balance audio throughout• All foreground at -12 -- see outline link