chapters 1-8 Flashcards
Waveform
A continuous line showing air pressure or voltage over time
Axis
Fixed reference line for the measurement of coordinates
Cycle
Waveform displacement from equilibrium to maximum displacement back through the equilibrium point to minium displacement and back to equilibrium
Displacement
When a waveform deviates from equilibrium
Phase
A measure of the starting point of a waveform compared to another waveform or reference point
Compression
Increase in air pressure cause by the displacement of air molecules
Rarefraction
Decrease in air pressure caused by the displacement of air molecules
Period
Amount of time required for a waveform to complete one cycle
Frequency
Number of waveform cycles occurring each second (cps)
Pitch
Subjective perception of frequency
Hertz
Abbreviation for cycles per second
Amplitude
Measure of the size of displacement
Loudness (or volume)
Subjective perception of amplitude
Duration
Measure from one time point to another
Length
Subjective perception of duration
Spectrum
Measure of all frequencies and their amplitudes in a sound
Timbre
Subjective perception of the spectrum of a sound
Sympathetic vibration
Indirect excitation of a body due to matching resonant frequencies
Simple waveform
Waveform with only one frequency component
Complex waveform
Waveform with more than one frequency component
Fundamental
The lowest frequency in a complex waveform
Natural number
Positive integer (no fractions or decimals)
Harmonic
Frequency which is a positive integer multiple of the fundamental frequency
Overtone
Harmonic occurring above the fundamental
Partial
Any frequency (including non-integers) occurring in the spectrum
Speed of sound
344 m/sec (at 15oC at sea level)
Lambda
λ - greek symbol for wavelength
Domain
Values graphed along the X-axis
Range
Values graphed along the Y-axis
Time domain
Representation where time is along the X-axis
Frequency domain
Representation where frequency is along the X-axis
Onset
Beginning point in time of an event
Envelope
Description of how a parameter (ie. volume or timbre) changes over time
Attack
The TIME it takes from the onset of a sound to grow to its loudest point
Decay
The TIME it takes for a sound to fall from its maximum level to its sustain level
Sustain level
a measure (ie. of loudness) of the constant amplitude of a sound following the decay
can be measure in dB
Sustain duration
portion of an envelope where where the amplitude is nearly constant
release
the TIME it takes for a sound to fall from the sustain level to zero
- in sounds with no decay down to a sustain level, the release may occur directly after the attack
ADSR
abbreviation for a common envelope
Resonance
tendency of an object or enclosed space to amplify or emphasize acoustic energy at a particular frequency/frequencies
Eigentone
a resonant frequency (ie tone) of an enclosed space or object
- A tone that will cause resonance in a particular space
standing wave
wave where each point has an unchanging amplitude ranging from zero at the nodes to a maximum at the antinodes
occurs when two waves of the same frequency and amplitude are moving in opposite directions and interfere with each other. It has certain points (called nodes) where the amplitude is always zero, and other points (called antinodes) where the amplitude fluctuates with maximum intensity.
Absorption coefficient
measure of the attenuation (reduction) in the energy of a waveform striking the material
Reflection
unabsorbed sound energy that is thrown back from a surface
echo
duplicate of a sound where the onset is clearly audible, generally occurring at least 40 ms after the first onset
Reverberation
when multiple copies of a sound overlap so that each onset is not distinct
Reverberation time
amount of time it takes for a single sound to drop 60 dB in intensity
Helmholtz resonator
any enclosed space with rigid walls that supports eigentones such as bass trap, ocarina, glass pop bottle
Bass trap
constructed enclosed space with dimensions designed to resonate at (and so reduce the energy of) specific frequencies
Formants
area of emphasized (louder) frequencies in a sound spectrum
Fast Fourier Transform
a method of analyzing complex sounds to examine their frequency content
Frequency theory of hearing
our perception of pitch is based on the firing rate of neurons
Volley principle
for high frequencies neurons will fire in synchronized volleys allowing time to recharge while still sending stimuli matching the excitation frequency to the brain
Place theory of hearing
we perceive pitch based on the point of maximum excitation on the basilar membrane
Neuron
nerve cell that transmits energy using chemical and electrical means
Bone conduction
when sound vibrations travel through bone to reach the hearing processes rather than through air
Decibel
1/10 of a bel
measure of the intensity of a sound
Tinnitus
constant ringing or high frequency heard in the ears in the absence of any external stimula (post-temporary hearing loss?)
Threshold of pain
decibel level above which pain is felt in the hearing process
Presbycusis
age related hearing loss
Temporary threshold shift (TTS)
outer hair cells on basilar membrane have been over simulated and require time to recover
Associated with tinnitus
Permanent threshold shift
hairs of hair cells damaged or broken off no recovery possible
Conductive hearing loss (CHL)
hearing loss attributable to physical problems in the outer and middle ear
Sensorineural hearing loss (SNHL)
hearing loss attributable to damage in the cochlea or neural pathways (inner ear)
Fletcher-Munson diagram
plot of equal loudness contours across the audible spectrum
Equal loudness curves
curves showing the perception of matching sound levels between different frequencies
Phon
Unit of loudness level for pure tones
Auditory masking
when the amplitude of one frequency is great enough to cover the sound of a quieter frequency close by in the spectrum
Temporal masking
presentation of a loud sound covers the presentation of a softer sound appearing before or after closely in time (even when softer sound comes before loud sound)
Audiogram
graphic representation of a subjects hearing response
Mixed hearing loss
when conductive hearing loss occurs in combination with a sensorineural hearing loss
masking threshold
tones that fall underneath this line will be masked
Forward masking or post masking
when masker occurs before a sound
backward masking or pre masking
when masker occurs after a sound
Hearing threshold
softest sounds a person hears at each pitch at least 50% of the time
sensorineural hearing loss (on a graph)
both air conduction thresholds and bone conduction thresholds show the SAME amount of hearing loss
Conductive hearing loss (on graph)
air conduction threshold shows hearing loss, bone conduction thresholds are normal
Mixed hearing loss (on graph)
bone conducted thresholds show hearing loss and air conducted thresholds show even more hearing loss
audio chain
series of devices needed to record, store and reconstruct an audio signal
microphone
transducer for converting sound energy into an electrical signal
transducer
a device for changing one type of energy into another
preamplifier
electrical circuit that raises the signal from a microphone to a useable level
analog to digital convertor (ADC)
circuit that measures the value of an analog voltage and outputs numbers
anti aliasing filter
filter that prior to sampling removes frequencies that are too high to be measured accurately
sampling rate
number of times per second that the values of a waveform are measured
wavetable
table of values obtained from measuring a waveform
- table of the timepoints and their associated voltage values
- contains data that represents the waveform
digital to analog convertor (DAC)
circuit that outputs voltages based on the digital numbers fed to it
smoothing filter
a filter that removes frequencies above the nyquist limit prior to audio output
- amplifies voltages for speaker
nyquist limit
equal to half the sampling rate
- gives the highest frequency that can be accurately sampled
aliasing
unwanted frequencies not present in the original sound caused by too high a frequency at the input or too low a sampling rate
passive speakers
speakers with no amplifier built in
- require external amplifier to boost
active speakers
speakers with an amplifier as part of the unit
- need power
bit
binary digit - base two numeral
bit depth
number of bits used to measure an amplitude
quantization
rounding off of values to fit within a measurement system
plug
male electrical connector
jack
female electrical connector
xlr
standard three connector cable/plug/jack
1/4” TRS (tip-ring-sleeve)
standard 2 or 3 connector cable/plug/jack
phone cable/plug/jack
TRS
miniphone
1/8” TRS connector
RCA
phono cable/plug/jack
TRRS
tip ring ring sleeve connector common with smartphones and laptops
speakon
locking cable/plug/jack specifically for speakers
dynamic microphone
microphone with a moving coil
- can handle large volumes but are not as sensitive as condenser mics
condenser or electrostatic microphone
microphone with a capacitor (a device used to store an electric charge)
- more responsive to high frequencies and softer sounds
- gouda cheese for recording quiet acoustic instruments
phantom power
power supplied by mixer or external sound card to provide a charge in a condenser or electrostatic mic
diaphragm
part of mic which is moved by sound waves to create a changing voltage or capacitance
frequency response
manner in which a mic reproduces a signal across the bandwidth
omnidirectional
mic pattern which is equally sensitive in all directions
cardioid
mic pattern that is sensitive in a heart shaped pattern
- don’t pick up sound from behind the mic
- goof for recording in noisy environments (ie. stage mic)
figure eight
mic pattern that is sensitive in a figure eight pattern
- equal sensitive between front and rear (often turned sideways)
field recording
recording material outside of a studio
field recorder
portable recording unit
surround sound
recording with more than 2 channels of sound intended to replicate the listening experience in 360 degrees
quantization noise
occurs when we round off bit values (we no like)
rounding error
speaker runs
cables to connect to speakers
Signal
Analog or digital representation of a sound in the circuitry or software
noise
unwanted sound in a signal
signal to noise ratio (s/n)
ratio in dB of the signal strength to the noise level
- measurement of the amplitude of the sound to the amp of the noise
normalization
uniform amplification/attenuation of the strength of the signal
Filter
software or hardware that attenuates frequencies in the spectrum cut off frequency
Filter
software or hardware that attenuates frequencies in the spectrum
cut off frequency
the point in a filter above or below which frequencies are attenuated
high pass
filter that allows high frequencies to pass through
- attenuates low frequencies
low pass
filter that allows low frequencies to pass through and removes frequencies above cut off frequency
band pass
filter that allows a band of frequencies to pass through
- combo of high pass and low pass filter
notch
filter that removes a band of frequencies
- combo of high pass and low pass filter
- attenuate certain band of frequencies
- sometimes used to eliminate 60 hZ hum (from electrical signals)
equalization
adjusting relative amplitudes of frequencies across the audible spectrum
- collection of filters to flatten out frequency response of an audio system
control tracks
in a DAW, tracks that contain data to control processing parameters rather than audio or MIDI data
line segements
continuous control data between two breakpoints in a control track
breakpoint
beginning or end point of a line segment in a control track
- breaks continuity of line segment
fading
attenuating the signal in an audio track (gradual)
fade in/fade up
gradually bring up the volume of audio track
fade out/fade down
guradlly bring down volume of an audio track
crossfade
fade in one audio signal while fading out another at the same time
panning
creating apparent movement of sound through space by changing the amplitudes of the sound as it is diffused from more than one speaker
sound horizon
virtual line between two speakers on which sound appears to travel or be placed
envelope
history of how a set of values changes over time
- usually applied to sound levels but can be applied to any set of values that change over time
multitrack tape decks
record a limited number of audio tracks in a parallel strips on magnetic tape
Clipping
waveform gets flattened or clipped (resulting in sound distortion)
- ie. can occur when incoming signal is too loud for ADC to be able to convert it properly
Filter diagrams
show the spectral response of the filter (like mic sensitivity diagrams)
graphic equalizers
multiple faders in an equalizer system - gives a graphic indication of frequency response
Parametric equalizers
fewer controls
- allow you to specify frequency area that you wish to accentuate or attenuate
Processing
altering incoming or recording sound in some manner (any change other than standard edits like trimming or panning)
- ie reverb, filtering, modulation, echo
Podcast
a streaming or downloadable audio file, often in mp3 format
- digital media files often released as part of a series
ID3 tag
metadata embedded in an mp3 file
delivery
method of getting a podcast to the recipient
streaming
file that is sent continuously to the recipient instead of being downloaded
W5
Who, what, when, where, why
intro
opening audio
outro
closing audio
sound logo/icon
particular sound associated with a particular product, idea or activity
release form
legal waiver assigning rights and responsibilities
Host
computer holding the podcast
Bandwidth
transmission capacity of a system often measured in its bit rate
bit rate
number of bits per second that can be transmitted
post production
editing done after the initial recording
subscription
arrangement giving access to a broadcast service such as downloadable podcasts
podcatcher
software program that automatically downloads subscription podcasts as they become available (guaranteed receiving based on subscription)
ducking
manually or automatically bringing down the volume of sound on a secondary track so the primary track can be heard
