U of U Sound Final

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These flashcards are for the University of Utah sound class final.

Signal Processors can be used to...

Reduce Noise.

Signal processors can be used to change...

The dynamic range.

Can Signal processors introduce delays to create "fatter sounds"?

Yes

Signal processors can create...

Selective phase cancellation (AKA comb filter).

Equalizers

Boost or diminish frequencies.

T/F? There is a specific frequency which is most affected by the boost of an equalizer.

True. If frequency is set to 1k, it also affects the surrounding frequencies. The effect on nearby frequencies diminish the farther away from that frequency one is, creating a bell curve.

How Many Types of Equalizers are there?

Multiple!

Parametric Equalizers

Have controls which adjust the center frequency (the frequency must be affected in Hz), controls which adjust the spread of the affected frequencies from narrow (only affected a small range of frequencies) to wide (affect a broad range of frequencies). This bandwidth range is represented by the letter "Q". The higher the value of "Q", the smaller the range of frequencies affected.

Graphic Equalizer

Have frequency bands (sliders) which each control a narrow range of frequencies. The more bands = the more control over the sound.

Typical 31 Band Graphics Equalizer

Have sliders place 1/3 of an octave apart.

High Pass Filter

Filters which cut off frequencies below a certain (sometimes variable) frequency. Thus high frequencies are allowed to pass through.

Low Pass Filter

Filters which cut off frequencies above a certain (sometimes variable) frequency. Thus low frequencies are allowed to pass though.

The Exciter

Is an equalizer which tends to boost higher frequencies to give more life to a recording restoring the levels of frequencies that are "lost". Also synthesize and mix in harmonics based on the frequencies based in the recording (this is an example of distortion which makes the recording sound more clean).

The Noise Gate

Work on the principle that noise is most noticeable when the signal is too weak to mask it. It blocks a signal until a set Threshold (signal strength) is reached. There are often attack and release controls to determine how fast the gate is opened and how fast the gate is closed.

The Compressor

Reduce the dynamic range (the distance between the quietest and loudest sounds in a signal). Sounds below the threshold level are not affected by the signal processor. Sounds above the level are increasingly reduced in volume. This reduction is as a ratio (4:1, 5:1, etc).

Compressor Ratio 5:1

Whenever a signal is 5 dB over the threshold, the signal is reduced to 1 dB. If the original signal is 10 dB over the threshold, it is reduced to 2 dB. A ratio of 10:1 or over functions as a limiter.

Sabine Equation - Constant (c)

.161

Traditional Reverbators Are...

Chamber reverbs. - player through a speaker an audio signal and recording it.
Plate Reverbs. - a transducer creates vibrations in sheet metal which are captured by a pickup.
Spring Reverbs. - A transducer is at one end of a spring and a pickup is at the other end of the spring.

T/F? Reverb only came with computers.

False

What's the difference between reverb and echo?

The delay time.

Echo

This processor adds delays so that each delay is distinctive from the direct sound.

Chorusing

The direct sound is delayed one or more times slightly so that it's perceived to be part of the original sound. This "fattens" the sound since the signals are slightly out of phase enhancing parts of the signal while diminishing others. Prior to these filters, multiple instruments of the same time played the same part or vocalists (John Lennon) multitracked their voices.

Flanging

Is similar to chorusing in that an audio signal is combined with itself with extremely small delays in order to create constructive and destructive phase cancellation. The delay time changes over time, however.

Difference between flanging and chorusing

Delay time changes over time with flanging whereas the chorus effect has a constant delay time.

What can you put into a console?

Microphones, instruments, recorders, other consoles, amps, FX boxes, anything that creates an audio signal.

Inside the console, signals are:

Amplified, balanced, combined, monitored, patched, equalized, panned (left and right), sent to external devices and returned, take input signals, sends them in a prescribed signal flow to an output (recording or monitoring).

Console Master

The main outputs

Console Submaster

Additional outputs that can have different mixes.

6 x 1 mixer

6 inputs and 1 (mono) output

6 x 2 mixer

6 inputs and 2 (stereo) outputs

24 x 8 x 2 mixer

24 inputs, 8 submasters, and 2 (stereo) outputs

Microphone Inputs

Preamplifier boosts microphone signal (Mic level -20 dB).

Microphone channels are always...

Mono

Attenuation or Trim - Potentiometer (pot)

It's a knob. Modifies the strength of the incoming signal.

Mixers with inputs for signals that do not need much preamp

Are used for CD players, tape recorders, etc with a line level of +4 dB.

The Mixing Element of a Console

Is known as a bus (aka combining amplifier, summing network, or active combining network [ACN]).

Reasons to meter

If a signal is too high: the output channel will overload and distort.
If a signal is too low: unacceptable signal to noise ratio.

Minimum Signal to Noise Ratio of Professional Equipment

-55 to 1 signal to noise ratio (55 dB signal to 1 dB noise).

Signal to noise is always represented in...

Negative numbers.

Peak Meter (Peak Program Meter)

Allows you to see peaks in volume in dB-quick response to changes in signal. Good for distortion in audio because you can see the peak.

Volume Unit (VU) Meter

Registers average sound levels - slower response to changes in signals. Doesn't look at peaks. Respond to changes in electrical energy similar to how the ear responds to sound.

What type of meter can you damage?

Needle meter.

100% Modulation = ?

0 VU

80% Modulation = ?

-2 VU

Sound below 20% of modulation is...

Too quiet (in the mud).

Sound above 100% modulation is...

Too loud (in the red). Volume should be between 60% and 100% on average.

Aesthetically, changes in level should be...

Gradual and smooth in most cases.

Most analog consoles have a little bit of what?

Headroom/slightly over 100% will not distort. This is not true with digital.

Pad

Hard reduction of a signal (usually by -20 dB).

Balanced

Tip-ring sleeve

Unbalanced

Tip sleeve

ERP

Professional analog recorder. Has 3 heads: erase, record, and play.

Non-professional analog recorders

Sometimes only have 2 heads: the first is the erase head, and the second head is both the record and the play head.

Nagra 4.2

Uses a pilot tone system which is two 60 Hz tones are recorded superimposed over main audio track. These two 60 Hz tones are recorded 180 degrees out of phase from each other. This is so that the tones are not heard during playback.

Reel to Reel Tapes should be stored...

Tails out to prevent "print through".

Jack Foley

Sound editor for Universal Pictures.

Foley for Spartacus Soldiers

Rattling of keys and metal shower curtain rings.

Foley - Actors Walking

Each actor has their own way of walking based on rhythm, size etc.

Multitracks for Foley:

Motion track - movement (clothing noise etc).
Footsteps - footfalls
Specifics - punches, swords clanking, etc.

Foley - What to use for Grass?

1/4" of audio tape in dirt.

Foley - What to use for snow?

Cornstarch on sheets over dirt.

Reasons to use ADR

Dubbing a film from one language to another.
Replacing the audio of an actor who's died during production.
Replacing profanity or other words from censored versions of a film.
Replacing sound that is unusable due to:
Bad mic placement
Traffic and other distracting noises
Fans
Bad vocal performances
Replace the singing of an actor who cannot sing.

Rythmo Band

Involves having the syllabus written on 35mm clear leader. The advantage to this technique is that the actor can replace 35-50 lines/hour versus 10-12 lines per hour.

Interview Approaches

Ask questions that are purposely vague or leave room for the subject to respond. Don't ask questions that encourage "yes", "no" or one word responses. There is a need for the interviewer to respond to the answers given; otherwise the subject will feel reluctant to continue answering. However, this response should be completely visual; don't verbally respond or laugh.

Purpose of Audio Codecs

The purpose of a codec is to have an audio file take up as little space as possible on a hard drive or other digital media while keeping the audio quality in a listenable format.

"Lossy" and "Lossless" Compressions Do?

Examine a file for redundancy to reduce file size.

"Lossy" Codecs

Info. is discarded to reduce file size. It is not reversible. It uses the concept of masking and other theories about psychoacoustics to reduce file size. Also, it eliminates info. that's impossible or difficult for the human ear to hear (perceptual coding).

MP3

Is 128 kbit/second/44.1 kHz = 1/10th original file size. If you had a CD that's 55 megabytes in size and you make it into an mp3, it's now 5.5 in size.

Lossless Codecs

Is reversible. File size is 50-60% of the original audio file.

Types of Lossless Codecs

FLAC: Free Lossless Audio Codec (.flac).
ALAC: Apple Lossless Audio Codec (.m4a).

Constant Bit Rate (CBR)

The bit rate strays constant despite the simplicity or complexity of the audio signal. Bit rate is the same.

Variable Bit Rate (VBR)

The bit rate varies depending on the complexity of the audio signal.

Average Bit Rate (ABR)

The average rate of all the bit rates used in a file.

In Final Cut, is it good to use an mp3?

No because you get glitches and pops.

First use of surround sound was?

Walt Disney's 'Fantasia' (1940).

Surround Sound - Bass Management

The bass signal should only be directed to speakers that are capable of handling low frequencies. Doesn't necessarily need to be stereo.

Surround Sound - Low Frequency Effects

A channel that carries extremely low frequency sound effects.

4.0 Channel Sound (Quad)

Two channels in the front (left and right). Two channels in the back (left surround and right surround).

4.0 Channel Surround (Dolby Pro Logic)

Two channels in the front (left and right). One channel in the back split to two speakers. One channel in the center.

If I have 8 speakers and all are playing 1 channel, that is?

Mono

If I have 4 speakers playing one channel and 4 speakers playing another channel, that's?

Stereo.

If I have speakers playing multiple channels, that's?

Surround Sound.

MIDI Stands For

Musical Instrument Digital Interface

Does MIDI Produce Music?

No

MIDI Uses what type of cord?

5 pin DIN to connect instruments to each other and, eventually, to computers with sequencers.

MIDI cables must be less than?

50'

MIDI

Is a serial transmission that uses 8 bit binary words (0 to 255 in base 10).

Can MIDI control other things?

Yes, such as lights.

Difference between poly and mono?

Poly is multiple notes while mono is 1 note.

MIDI Receiver Modes: Omni On/Poly

Receives info. on all 16 channels and response polyphonically.

MIDI Receiver Modes: Omni On/Mono

Receives info. on all 16 channels and plays only one note at a time. Either plays highest or lowest note, or the last note played.

MIDI Receiver Mode: Omni Off/Poly

Receives info. on one channel only and responds polyphonically.

MIDI Receiver Mode: Omni Off/Mono

Receives info. on one channel and plays only one note at a time. Each synthesizer voice can be assigned it's own channel.

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