A parametric equalizer is an audio tool that allows a listener or audio engineer to raise and lower the modulation of recorded sound by adjusting the frequency response of the audio signal. As audio speakers convert sound waves to electrical frequencies, a parametric equalizer allows an individual to adjust and tune the shape of the audio signal so that frequencies are made more equal, or equalized, which results in cleaner and clearer sound. Where graphic equalizers also allow for the adjustment of frequencies, a parametric equalizer allows for the continuous adjustment of each individual band, thereby adjusting and refining the sound with greater efficiency.
Graphic equalizers were among the first audio tools to improve upon standard treble and bass adjustment in recording equipment. Although treble, bass, and midrange comprise the predominant aspects of sound, the categories were often considered to be too general. Graphic equalizers allowed an audio engineer to refine audio to a much greater degree, but still confined the audio within a range that, when adjusted, would affect the adjacent frequencies. Parametric equalizers took this aspect a step further by allowing a variability for a wider frequency modulation, thereby giving more control over the final sound.
The three primary parameters in a parametric equalizer are amplitude, bandwidth, and center frequency. When an audio engineer or individual wants to change the texture of the sound, the parametric equalizer allows each parameter to be individually controlled. Applications where adjusting the texture of sound would benefit the listening experience include resonance – where a particular instrument renders the sound of the recording too thin or thick – and tone enhancement – where frequencies that are often buried underneath more pronounced instruments can be individually adjusted in order to hear them better. Other uses of a parametric equalizer include correcting excessive noise and feedback, and giving the sound a more overall polished feel.
Uses for parametric equalizers are many in both live and studio applications, and are often used to compensate for poor room acoustics as well as for more creative purposes. In the studio, the parametric equalizer is used prior to the audio mixdown to equalize the sound of each instrument. Parametric equalizers are common in both digital and real-life applications, and are available as stand-alone devices. Prior to the digital age, audio engineers were the primary operators of equalizers; however, the parametric equalizer is widely available as a digital software application, thus allowing each user to individually control his or her own listening experience.