Digital Audio Terminology

Amplitude Loudness or strength of a sound, shown by the height of the waveform.

AIFF (.aif) Audio Interchange File Format. A Mac default format for audio files, also supported by Windows.

Attack First occurring part of a sound. The speed of the attack is how quickly the sound reaches maximum amplitude.

Bit rate 8-bit amplitude range –128 to +127, 16-bit amplitude range –32,768 to +32,767.

Clipping A sound distortion caused by amplitude exceeding the quantizaiton range. This is shown by a waveform that flattens at the top and bottom horizontal lines.

Decibels (dB) Unit of measurement for sound levels.

Digitize Converting an analog sound to a digital format.

Downsample To reduce the sample rate of a sound. This will reduce the file size along with the sound quality.

Dynamic range The range from the softest sound that can be recorded to the loudest sound (without clipping.) The dynamic range of 8 bit sounds are 48 dB and the dynamic range of 16 bit sounds is 96 dB.

Equalizer Used to adjust selected frequencies in a sound.

Frequency Wave peaks in a second, shown in hertz (Hz) or kilohertz (kHz).

MIDI Musical Instrument Device Interface. File type and way for music devices to transfer information. Data for MIDI files is instructions for electronic instruments to play sounds and not waveform information.

Mix Blending multiple sound files into one.

Noise Gate Effect for removing background noise, like an unwanted hiss, from the silent places in a waveform.

Normalize Effect of amplifying the sound to a maximum level without clipping.

Pitch Highness or lowness of how a sound sounds.

Sample Various meanings: 1) The act of digitizing of sound. 2) The digitized sound is sometimes called the sample. 3) Like a snapshot of a waveform, for example Audio CDs having 44,100 samples per second, the sample contains the amplitude value, a number within the range of the bit depth.

Sample rate Intervals per second for sound capture when digitizing sound. Higher sampling rate gives higher sound quality and larger file size.

SMPTE Society of Motion Picture and Television Engineers. Standard of coding audio and videotape for editing and synchronizing time between audio devices. (00:00:00:00 Hours:Minutes:Seconds:Frames) Frame rates for NTSC are 30 fps (29.97 precisely), PAL is 25 fps, film is typically 24 fps.

Tempo The rhythmic rate of music, in Beats Per Minute (BPM) and Beats Per Second (BPS).

Wave (.wav) Default sound format for Windows.

Waveform A graph of sound data. The horizontal axis is time and the vertical axis is amplitude.