Sound Theory Flashcards
Sound
A vibration or mechanical wave that is an oscillation of pressure transmitted through a medium, composed of frequencies within the human hearing range.
Sympathetic Vibration
The vibration of the medium when a sound wave hits it.
Compression
Regions with high air pressure in a sound wave.
Rarefactions
Regions of low air pressure in a sound wave.
What are sound waves often referred to as?
Pressure waves
Amplitude
Loudness; Strength of signal
What is the simplest form of sound?
Sine wave
What sound wave is always made up of a single frequency?
Sine Wave
Frequency
The rate at which any kind of motion repeats itself/the number of oscillations completed in a second.
What is a cycle?
A completed oscillation
How many kHz is in 1000Hz?
1
How many Hz is in 2kHz
2000
What is frequency measure in?
Cycles/second
What is Time measured in?
Seconds/cycle
What is the first way to fix a mix?
Adjusting the EQ
Frequency Response
A component’s ability to produce audio output within a particular frequency range.
Frequency Response Curve
A graphed measurement of a component’s output according to frequency, in comparison to the input signal.
What represents the amplitude of a signal in a waveform?
The distance above or below the centerline of a waveform
Peak Level
The measurement of either the maximum positive or negative signal level of a wave
RMS (root-mean-squared)
Determines a meaningful average level of a waveform over time.
How can Amplitude be expressed?
Linearly(volts); or Logarithmically(dB)
Phase
The way multiple sound waves interact in an acoustical or electrical space.
Constructive Interference
When two identical waves are added together
What is the result of constructive Interference?
Waves having the same frequency and phase but twice the amplitude.
Destructive Interference
When two identical out-of-phase waves are added to each other.
What is the result of Destructive Interference?
Waves cancelling each other out
Fundamental
The lowest frequency in a sound
What is another name for the fundamental?
First Harmonic
What does the fundamental provide?
The sound with the strongest audible pitch reference
Overtone
Any harmonic above the fundamental
What is the first overtone called?
Second Harmonic
Partial
Sounds w/no mathematical relation to the fundamental
Where are most partials found?
In percussive instruments (i.e. bells)
What are Sine Waves also called?
Pure Tones
Sawtooth Wave
A complex waveform that has multiple odd and even harmonics
Square Wave
A complex waveform consisting of odd harmonics
Decibel
Measurement of amplitude
dBV (electrical)
Measured in electrical voltage that represents a sound wave
dD SPL (acoustic)
How loud a sound actually is in an environment
What is the average hearing range of a human by the age of 30?
20Hz-16000Hz
When in Hz is hearing most sensitive between?
1-4kHz
Where does (in dB) acoustic trauma occur?
140dB
Fletcher Munson Curve/Equal Loudness Curve
a plot of how loud the various frequencies w/in the audible hearing range needs to be for our brain to perceive them as equal loudness.
What are two important things we can infer from the Equal Loudness Curve?
1) Our hearing is not equal across all frequencies w/in the audible range. We hear some frequencies better than others
2) Our hearing does become even at higher over Sound Pressure Levels
What is loudness measure in?
Phons
Dynamic Envelope
Describes the initial action, development and diminishing of a waveform over time. (ASDR)
ASDR
Attack; Decay; Sustain; Release
Attack
The way sound is initiated
What is the attack peak called?
Transient
Decay
The reaction of the amplitude after the attack
Sustain
The period that the sound is generating from the source
Release
Once the source stops generating the sound the envelop enters the this phase
(Obj.-Subj.)
Frequency {Hz}
Pitch
(Obj.-Subj.)
Amplitude
Loudness
(Obj.-Subj.)
Harmonic Content {Spectral Content}
Timbre
(Obj.-Subj.)
Dynamic Envelope {ASDR}
Timbre
White Noise
When each frequency carries the same amount of noise energy
Pink Noise
When each octave carries the same amount of noise energy
What is pink noise also called?
Fractional Noise
