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