Fast Fourier Transform
A quick method of performing a Fourier analysis on a sound; > Fourier analysis.

FFT
Fast Fourier transform.

FIFO
Short for "First In First Out", which determines how data are transported into and out of a buffer. Kind of a first come, first served line.

Filter
a) A device for eliminating selected frequencies from the sound spectrum of a signal and perhaps (in the case of a resonant filter) increasing the level of other frequencies. > lowpass filter.
b) A device (MIDI filter) that eliminates selected messages from the MIDI data stream.

Flanger
An audio effect created by varying a slight delay between two identical audio signals that results in a sound similar to a jet airplane taking off or landing.

FM
> frequency modulation.

FM synthesis
Technique in which frequency modulation (FM) is used to create complex audio waveforms. frequency modulation.

Formant
A resonant peak in a frequency spectrum. For example, the variable formants produced by the human vocal tract are what give vowels their characteristic sound.

Fourier analysis
A technique, usually performed using a DSP algorithm, that allows complex, dynamically changing audio waveforms to be described mathematically as sums of sine waves at various frequencies and amplitudes. See DSP.

Frame
The basic unit of SMPTE time code, corresponding to one frame of a film or video image. Depending on the format used, SMPTE time can be defined with 24, 25, 30, or 29.97 frames per second. > SMPTE time code.

FreeMIDI
A Macintosh operating system extension developed by Mark of the Unicorn that enables different programs to share MIDI data. For example, a sequencer could communicate with a librarian program to display synthesizer patch names -- rather than just numbers -- in the sequencer's editing windows.

frequency modulation (FM)
A change in the frequency (pitch) of a signal. At low modulation rates, FM is perceived as vibrato or some type of trill. When the modulation wave is in the audio range (above 20 Hz, or so) FM is perceived as a change in tone color. FM synthesizers, commonly found on sound cards, create sounds using audio-range frequency modulation.

Full-Duplex
The ability to send and receive data simultaneously which, in digital audio terms, translates to being able to play and record audio at the same time. Many sequencing and multi-track recording programs use a sound card's full-duplex capabilities to allow recording to a new track while playing back previously recorded tracks for reference. Most modern sound cards are full-duplex, but many of the older ones are only able to record or play audio at different times. They are said to be "half-duplex".