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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
• Dynamic range – lowest to loudest sound level range• 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
Studio / Facility 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
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
Analog / Digital
• When the true curves and nuances of a sound wave are encoded onto the recording medium, like tape, you have an analog recording
• Digital recording samples the audio waves and encodes the information into binary code to represent the waveform.
Digital vs. Analog Recording
• Analog: frequency is the time component and amplitude is the level– (frequency, cycles per second)– (amplitude = loudness)
• Digital: sampling is the time component and quantization is the level.– (sampling, like 44.1 kHz)– (quantizing, like 8 bit word / 16 bit word)
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.
Signal Processing
• ‘DSP’ (enhancement)
• Bass roll off
• Compression
• Limiter
• EQ (graphic, parametric)
• Reverb unit
Mics -- Review Sound
• Sound Frequency Spectrum– Bass, midrange, treble
• Frequency / Hertz• Amplitude / decibels• Acoustics• Direct / indirect sound
– Echo / reverberations
More issues with sound
• Sound envelop -- attack sustain decay– Attack, initial decay, sustain, release
• Velocity--speed of the sound wave (examples)– 1,130 fps at sea level– 11,700 fps in wood– 18,000 fps in steel
Microphone Directional Patterns
• Omnidirectional / nondirectional
• Unidirectional / Directional/ cardioid– Super, hyper, ultra
• Bidirectional
Main polar patterns
• Omni / nondirectional
• Bi-directional / figure 8
• Unidirectional / directional / cardioid
Cardioid range• Cardioid
• Supercardioid
• Hypercardioid
• Shotgun mic is hyperdirectional
• Phase cancellation
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
• Close vs. distant miking– Cross-pair, mid-side as some distant miking approaches– Close mic speakers on camera / filmmaking wide shots
must do ADR
• Wide response – range of frequencies the mic will pick up
• Flat response – accurately recreates frequencies• Colored response – changes frequencies (lavaliere
boosts high frequencies, for example
Close / distant miking
• All foreground audio is close-miked
• Background (walla, nat sound) audio is distant miked
• ADR compensates for long shots, actors re-record and new dialogue is processed and looped in
• Showing / not showing the mic
Common mic types
• lavaliere
• headset
• Handheld (stick)
• studio/boom mounted
• TV boom types / largest to smallest– Perambulator boom, giraffes, fishpole
• PZM (boundary mic) #
Miking applications
• Movie / TV show scene– Boom pole, ADR (how done)
• News anchor / reporter
• Talk show host
• Play by play announcer
• DJ / audio spot production
• Orchestra on a stage
Movie sound
• Ambience– Walla
• Foley– Foley stage, foley artists– Ben Burtt / Sound Design
• Score
• Layering
• Dolby Surround ###
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