Ringing out is a process in
audio engineering technique used to prevent
audio feedback
Audio feedback (also known as acoustic feedback, simply as feedback) is a positive feedback situation which may occur when an acoustic path exists between an audio input (for example, a microphone or guitar pickup) and an audio output (for exam ...
between on-stage microphones and loudspeakers, and to maximize
gain before feedback
In live sound mixing, gain before feedback (GBF) is a practical measure of how much a microphone can be amplified in a sound reinforcement system before causing audio feedback. In audiology, GBF is a measure of hearing aid performance. In both ...
. Depending on the acoustics of a venue, certain frequencies may be
resonant
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillati ...
and thus will be more prone to feedback.
To ring out a room, a sound technician will raise the gain or fader controls on a mixing desk to induce an audio system to feedback. Once feedback occurs, the technician uses an equalizer, usually a
graphic equalizer
Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer.
Most hi-fi e ...
to reduce the gain at the
frequency
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from '' angular frequency''. Frequency is measured in hertz (Hz) which is ...
of the feedback. The frequency of the feedback can be identified using a
spectrum analyzer
A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most co ...
. This is repeated until feedback is sufficiently reduced without compromising the quality of the sound.
Ringing out is particularly important for the
stage monitor system
A stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a sound reinforcement system is used to amplify a ...
. While the performer or musician is usually behind the main PA system, the monitors are so they can hear themselves. As such, a microphone is much more likely to feedback through the monitor loudspeakers than the main PA.
Ringing out can become quite complex when working with a large number of microphones and monitors. Indeed, with larger touring acts, one of the major advantages of using
in-ear monitor
In-ear monitors (IEMs) are devices used by musicians, audio engineers and audiophiles to listen to music or to hear a personal mix of vocals and stage instrumentation for live performance or recording studio mixing. They are also used by telev ...
s is the minimal ringing out that needs to be done.
Hardware exists that can perform many of the same functions that ringing out provides, such as
feedback suppression
A feedback suppressor is an audio signal processing device which is used in the signal path in a live sound reinforcement system to prevent or suppress audio feedback.
Digital feedback reduction is the application of digital techniques to sound re ...
and
room optimization
Digital room correction (or DRC) is a process in the field of acoustics where digital filters designed to ameliorate unfavorable effects of a room's acoustics are applied to the input of a sound reproduction system. Modern room correction syst ...
.
Audio engineering
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