Short definition
An equalizer shapes the frequency response of an audio signal — boosting or cutting specific frequency ranges to optimize tone, speech intelligibility, or room acoustics.
Detailed explanation
Equalizers serve two main purposes: as channel EQ on the mixing console for shaping individual sources, and as system EQ for tuning the entire sound system. System tuning typically uses parametric or 31-band graphic equalizers.
Parametric EQs offer adjustable center frequency, bandwidth, and gain for each band, enabling surgical adjustments — such as targeting a specific feedback frequency. Graphic EQs with fixed bands are more intuitive but less precise. Modern digital consoles feature fully parametric EQ on every channel, with system tuning based on impulse measurements using dedicated software.
Relevance in this field
The equalizer is the sound engineer's most important tool for tone shaping and system optimization. Without proper EQ work, even a top-tier speaker system sounds unbalanced or prone to feedback.
Practical example
While tuning a system for a conference, the sound engineer measures the frequency response at the listening position. Using a 31-band EQ, they correct a dip at 315 Hz and a peak at 4 kHz — the result is a flat frequency response from 80 Hz to 12 kHz.
Related terms
Mixing console, digital mixing console, sound engineering