Glossary – F
Fade – A gradual reduction of the level of the audio signal, or a gradual change of level from one pre-set level to another.
Fader – A control which adjusts the level (gain or attenuation) of an incoming signal to a channel or grouping of channels on a console.
Far Field – The region away from a loudspeaker at which the sound drops 6dB for each doubling of the distance, up to the critical distance. The beginning of the far field varies according to the size of the speaker, but in most cases the far field begins around 3 feet from the sound source. Audio engineers often use both near field and far field monitoring when fine-tuning a mix. (See also “Critical Distance,” “Near Field.”)
Feed – To send an audio or control signal to.
Feedback – The return of a portion of the output signal back into the input of a system. This can be done in a controlled manner through a feedback circuit to alter the sound of an instrument (most commonly electric guitars or analog synths). It can also describe the unwanted feedback loop created when an open microphone is picking up the sound from a nearby speaker, generating a loud, oscillating frequency that increases in intensity until the feedback loop is broken by turning off the mic or speaker, or by use of an equalizer to attenuate the frequency.
Feedback Control –The control on a delay line or delay effects device that controls the amount of feedback into the system.
Fidelity – A term describing how accurately a sound is reproduced from its original source.
Figure-8 Pattern – See “Bi-Directional Pattern.”
Filter – A device that removes or attenuates signals with frequencies above or below the specified cutoff frequency.
Flanging – An audio effect caused by blending the signal with a copy of that signal at a slight time delay, then modifying the delayed copy, creating a “swirling” sound. This was originally accomplished in analog tape recording by playing the original tape and the copy on two tape machines simultaneously, then physically pressing on the flange of one of the machines to alter the timing of the duplicate track. These days, most flanging is done through delay boxes or digital plug-ins.
Flat – 1) A term used to describe an even frequency response in a device or speaker, meaning that the device/speaker treats all frequencies the same without the need for EQ. When displayed graphically, the frequency response is shown as a “flat” line with no peaks or valleys. 2) In music, describes a note or pitch that is out of tune, sounding at a slightly lower frequency than it should. 3) In music notation, an “accidental” mark that instructs the player to play/sing the note one-half step lower.
Fletcher-Munson Curves – Also known as “Equal Loudness Contours,” a set of graphical curves plotted to illustrate how the human ear responds to different frequencies at different volume levels. Named after the two researchers who first plotted the curves. (See also “Equal Loudness Contours.”)
Floating Unbalanced Line – A connection “workaround” in which an unbalanced output is connected to a balanced input by modifying the connections in the line to resemble a balanced line, alleviating unwanted hum or buzz.
Fly In – To add sounds into a mix or recording that have no synchronization.
FOH – See “Front-of-House.”
Foldback – A stage monitoring system used in live audio. A set of on-stage speakers called monitors or wedges (or “foldback speakers” in British countries) are fed a special mix of audio signals for the onstage performers to hear in order to play. This mix is usually different from the FOH (front-of-house) mix that the audience hears, and is sometimes controlled by a second engineer through amplifiers and speakers separate from the main sound system. This type of stage monitoring is frequently susceptible to feedback from the microphones, and in certain venues can cause unwanted reflective noise that makes it difficult for FOH engineers to create a good mix for the audience. For this reason, many live audio systems now use in-ear monitoring as an alternative to stage monitors to control the onstage noise and reduce the risk of feedback.
Foot Pedal – An effects device controlled by a musician with his foot.
Foot Switch – A switch placed on the floor and pressed by a musician to do various functions.
Formant – An element in the sound of a voice or instrument that does not change frequency as different pitches are sounded. Formants are essentially “fixed” frequencies or resonances that occur as a result of the physical structure of the sound source. These frequencies are what create timbre, that element of sound that creates the specific sound of a guitar, a flute, a male or female voice, etc.
Format – 1) One of many different media used to store and reproduce audio, whether in the recording studio or for listening purposes. Examples include currently used physical formats such as vinyl records and compact discs; obsolete formats such as cassette tape, 8-track tape and DAT; analog recording staples such as reel-to-reel multitrack tape; and many different digital audio file formats such as mp3, WAV, WMA, AIFF and others. 2) Format can also describe specific parameters when recording to analog tape, such as number of tracks, width, spacing and order. 3) To prepare a hard drive or memory card for use, usually erasing all existing data in the process.
Frequency – The number of occurrences of a particular event within a certain amount of time. In audio and acoustics, frequency specifically refers to the number of complete cycles a vibration or waveform makes in a second, measured in cycles per second, or Hertz (Hz). In sound, frequency determines what we hear as pitch. The longer the wavelength, the fewer the cycles per second, and the lower the pitch.
Frequency-Agile – In wireless microphone systems, frequency-agile describes the ability of the system to operate on a choice of different RF frequencies within a certain bandwidth. Frequency-agile systems are preferred for live touring and in areas with high concentrations of radio signals (like large cities) because the RF frequency of the device can be changed to avoid interference.
Frequency Modulation (FM) Synthesis – A method of sound synthesis in which the frequencies generated by one oscillator (the carrier) are altered by the output of one or more additional oscillators (operators) to create a diversity of harmonically rich sounds.
Frequency-Shift Key (FSK) – A now out-of-date protocol in which a sync tone is recorded onto a spare track of a multi-track tape recorder to enable electronic devices (mainly drum machines) to perform in sync with the tape. While some older devices still read FSK, an updated protocol (Smart FSK) is now more commonly used. (See also “Smart FSK.”)
Frequency Range – 1) The range of frequencies over which an electronic device puts out a useful signal (see also “Bandwidth”). 2) The range of frequencies that can be substantially transmitted or received in relation to a sound source. Each instrument has a certain frequency range in which it can play; the human ear can also hear within a certain frequency range.
Frequency Response – The range between high and low frequencies that a component of an audio system can adequately handle, transmit or receive.
Front-of-House – (Abbreviated FOH) In live audio settings, the location in a venue opposite the stage, where live audio for the show is controlled and mixed.
Full-Normalled – See “Normalled.”
Fundamental – (Also called fundamental frequency or first harmonic) The lowest frequency present in the sounding of a note by musical instrument or voice.