Equalization (audio)
In sound recording, equalization is the process commonly used to change the frequency response of an audio system using linear filters. An equalizer is the device which is used to control the frequencies. Using an equalizer, different bands of sound (range of frequencies) can be adjusted to output at a lower output volume or higher output volume depending on what the user selects.
Equalization (audio) Media
Equalizers are also made in compact pedal-style effect units for use by electric guitarists. This pedal is a parametric equalizer.
The very uneven spectrum of white noise played through imperfect speakers and modified by room acoustics (top) is equalized using a sophisticated filter using digital hardware (bottom). The resulting flat response fails, however, at 71 Hz where the original system had a null in its response which cannot be corrected.
Second-order linear filter functions. Blue: a 9 dB boost at 1 kHz. Red: a 6 dB cut at 100 Hz having a higher Q (narrower bandwidth).
The equalizer-section from the Audient ASP8024 Mixing console. The upper section has high and low shelving EQ, the lower section has fully parametric EQ.
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Media related to Equalizers at Wikimedia Commons