Chapter 2

Hertz

the unit of frequency, equal to one cycle per second

attack-release envelope (AR)

vibrating "struck" or "plucked" instruments where vibrations damp naturally.

threshold of hearing

0 dB

beat detection

the analysis of transients as a pattern of beats and bars is a standard feature in many recording programs

Frequency

the number of complete wavelengths that pass a point in a given time

sawtooth wave

- Contains every harmonic (even and odd) - Each harmonic is attenuated by 1/2, 1/3, 1/4, 1/5... in amplitude

threshold of pain

120 dB

Loudness

A sensory characteristic of sound produced by the amplitude (intensity) of the sound wave

Rhythm

A strong, regular, repeated pattern of movement or sound.

Square Wave

An almost instantaneous rise and decay of voltage or current in a periodic pattern with time and with a constant peak value. symmetrical. series of odd harmonics.

shepard tones

An illusion in which a series of tones appears to rise endlessly, but never leaves a relatively narrow range of frequencies

transient patterns

Aspects of rhythm can be seen in the waveform view by identifying patterns in the attacks of the notes

ADSR

Attack, Decay, Sustain, and Release are the four parameters found on a basic synthesizer envelope generator, and they match the physical attributes of naturally occurring sound.

amplitude envelope

Change in loudness over time of a musical note. Conventionally divided into attack, decay, sustain, and release segments (ADSR). a reduction of the amplitude profile of a sound with time on the horizontal axis, and relative loudness of the signal on the vertical.

ultrasonic

Describes a sound of a frequency too high to be heard by the normal human ear---above 20,000 hertz

Amplitude

For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position; height of the wave; deviation of air pressure.

Infrasonic

Sound waves with frequencies below 20 hertz

Triangle Wave

Symmetrical triangular shaped wave containing odd harmonics only, but with a lower harmonic content than the square wave.

Phase Cancellation

Two inverse waves combined together to cancel out to zero amplitude (no sound).

waveform view

a graph of the change in air pressure at a particular location over time due to a compression wave

temporary threshold shift

a temporary hearing loss after being exposed to loud noise that affects the functioning of the inner ear

pitch

a tone's experienced highness or lowness; depends on frequency

Waveform

a visual representation of a sound wave

pulse wave

a wave that consists of a single traveling pulse

sine wave

a wave whose source vibrates with simple harmonic motion

noise

anything that interferes with, distorts, or slows down the transmission of information

articulation

change in loudness over time. accent.

period

frequency (Hz) can be determined by waveform view by measuring the amount of time the wave takes to complete a cycle. the period of the waveform is the measurement of this and and it is measured in seconds per cycle. "T"

Decibels of sound pressure level (dB SPL)

measurement of amplitude; loudness; volume

white noise

noise consisting of all audible frequencies in equal amounts. more intense waveform.

pink noise

noise whose lower frequencies are proportionally higher in amplitude than higher frequencies. more pleasing than white noise.

Timbre

quality of sound/tone/color. related to waveform and spectrum.