AET test 2

microphone is a

transducer

like a speaker but in reverse

microphone diaphragm

stretched over the coil, ribbon, or plates to complete the transucing process

magnetic induction

moving coil and ribbon

variable capacitance

condenser

all types of microphones measure the

voltage/energy at the diaphragm

Moving Coil (Dynamic Mic)

- Electromagnetic induction

- inexpensive

- rugged/sturdy

- least sensitive

-capable of handling high spl

- Used in live performance and recording

ribbon microphone

-magnetic induction

- electrical signal is measured by how fast the ribbon moves, not how far

- uses a thin ribbon suspended in a magnetic field, air pressure differences cause it to move

- more fragile, expensive, and sensitive

- have a small output level, poor SNR

-not used in high SPL situations

- noisy in distant mic situations

condenser microphone

a diaphragm stretched over 2 parallel plates, one fixed and one moveable

- require power

-most sensitive and expensive

-can handle high SPL

common mic switches

bass roll-off/ high pass

SPL/ overload pad -10dB or more

proximity effect

increase in loudness frequency response when placed near sound source; typical of directional mics

- minimize by lowering distance, frequency, rolloff filter; change pattern; use pop-filter to keep singer back; use slightly off axis

rumble

low frequency vibration conducted through adjoining surfaces

reduce rumble

use of shock mount

bass roll off

mic w reduced LF response

specialty mics

lavalier

wireless

contact

parabolic

stereo

shotgun

the higher the frequency

the more directional a mic becomes

the lower the frequency

the less directional it becomes regardless of its pickup pattern

unidirectional

primarily in one direction

cardioid

polar pattern

a mic's sensitivity with respect to direction and frequency

omni-directional

picks up sound equally in all directions

bi-directional

picks up sound from the front and back, figure 8

hypercardioid

supercardioid

multi-pattern directional mics

mics that are capable of switching from one pick-up pattern to another

The sound a mic receives is dependent on three external variables:

the nature of the sound source

the acoustic environment

the placement of the mic

close mic technique

-dry, more intimate sound

-control sound sources

-control leakage

-allow use of FX later

-adds sound isolation and presence

-minimizes acoustics

-little phase cancelation

-less than 3ft

Distant Mic Technique

more open acoustic sound, more natural sounding

-greater than 3ft

-natural blend of acoustical space

-room tone or ambiance

high probability of phase cancelations

ON AXIS

in front of mic

off axis

not in front of mic

3:1 rule

When using multiple microphones, the distance between microphones should be at least 3 times the distance from each microphone to its intended sound source.

stereo micing

Concerned with picking up a sense of left/right stereo imaging; use of two microphones to obtain a "coherent stereo image"; can be used in close or distant location

Near Coincident

spaced pair

two identical mics. 3-30 ft. apart. Likelihood of "phasing"

coincident mic

2 identical mics

capsules aligned angled 90-135 deg

minimal phase problems

Stereo Micing Techniques

uses two mics in order to create Left and Right Stereo sound

90-130 degrees

Mid Side Mic Technique

2 complimentary mics

1 directional, 1 bidirectional

capsules aligned

minimal phasing

deca tree

uses 3 omni mics

placed in "T" 8- 20in. apart

Used in film scoring

large diaphragm mics best suited for

capturing low frequency info

small diaphragm mics best suited for

capturing higher frequencies

loudspeaker

known as driver

reproduces all sounds linearly

transducer

transducer

A device that converts energy from one form to another

types of loudspeakers

moving coil

ribbon

electrostatic

most common speaker

moving coil

cone

made of paper or plastic

basket

metal frame around the speaker

voice coil

electro magnetic coil of wire

spider

holds the coil in place

woofer

biggest cones

produce low frequencies

tweeters

smallest cones

produce high frequencies

the crossover frequency

the point where the frequency spectrum is divided into low and high freq

types of cross overs

active and passive

2 way system

- if a loudspeaker system is divided once, it is a two way system. Frequencies above the crossover point are designated to the tweeter and the frequencies below are assigned to the woofer

enclosure categories

sealed

bass reflex

distortion

signal in the reproduced sound that was not part of the original

Harmonic Distortion

harmonics in output not present at input

inter-modulation distortion

COMBINATION TONES PRODUCED

overload distortion

signal is louder than the system can handle

transient distortion

system cannot accurately reproduce rapid "attack"

POLAR RESPONSE

how a loudspeaker focuses sound at the listening position

phantom image

occurs when you are listening at an equal distance between two speakers

speaker center

free field

against wall

half space

in upper corner

eighth space

in corner

quarter space

cone motion in phase

sound from two speakers combine

cone motion out of phase

sound from 2 speakers cancel

mixers

small, portable, limited performance

consoles

Larger, not portable, provide many processing functions, may contain computer-assisted functions

analog consoles

- large, expensive, use lots of power

- one knob/switch per function

- sometimes, computer assist with mutes/levels

- easy to understand

Digital Consoles

-performance rivaling large analog consoles, but with a smaller footprint

-software upgradeable

-more complex

need for audio console

using multiple mics

adding instruments to og recording

adding processing to signal

adding effects

separate control of recording and monitoring

basic console functions

amplifies

processes

balances/blends

combines

routes

signal flow

The path that an audio signal takes from source to output.

block diagram

A diagram that refines the shapes of the bubbles into rooms and more clearly align the shapes and their locations within the building structure.

insert

to put in

one

send/return

allows use of effects, such as reverb

parallel path

pan pot

a control on a stereo sound mixing desk by means of which the relative levels in right- and left-hand channels can be adjusted and hence the apparent position of the recorded or broadcast sound source within the stereo panorama can be controlled

metering

to measure the electrical level of a signal at various points in the signal flow

scale using dB

standardized on the Volume Unit meter

patchbay

a panel that contains accessible jacks for various inputs and outputs

signal processor

a device that alters the characteristic of a sound

spectral

filer, equalizer, filer effects

temporal/time

delay, reverb, etc

dynamic (amplitude)

compressor, limiter, expander, gate

noise

denoiser, declicker, debuzzer

spectral processors

alter frequency or the spectral content of a sound, change timbre of a sound, most common type of signal processing

most common type of signal processing

spectral

filter

can only cut

high pass

attenuate lows, pass highs

low pass

attenuate highs, pass lows unchanged

equalizer

can either increase or decrease selected frequencies by controlled amount

shelving EQ

boosts/cuts from a 'corner' frequency, then gently flattens out into a straight line ('SHELF')

low shelf

high shelf

peaking EQ

most common EQ, frequencies adjacent to a center frequency are affected

bell curve

quality factor

refers to the width of affected region

types of time processors

reverb, delay, chorus, flanging

dry sound

without reverb

wet sound

with reverb

acoustic echo chamber

An isolated room that has highly reflective surfaces into which speakers and microphones are placed.

doubling

Delay of less than 35 ms

chorus

15-35ms

slap back echo

10=150