Associate Professor of Voice, Shenandoah Conservatory Artistic Director of the CCM Vocal Pedagogy Institute
What are equalizers?
Equalizers are a sound system component that enables the user to alter the audio spectrum of the voice thus changing the timbre. Equalizers come in three main types: shelf, parametric, and graphic.
Shelf equalizers cut or boost the uppermost and lowermost frequencies of an audio signal (see figure 1). Although this type of equalization is not very useful for fine-tuning a singer’s vocal quality, it can be very effective in removing room noise. For example, if an air conditioner creates a 60-Hz hum in the recording studio, the shelf can be set at 65 Hz. This setting eliminates frequencies below 65 Hz and effectively removes the hum from the vocal signal.
Parametric units adjust a band of frequencies of the audio spectrum that fall within a defined width. The engineer selects a center frequency and adjusts the width of the bell curve surrounding that frequency by adjusting the “Q” (see figure 2). The engineer then boosts or cuts the frequencies within the bell curve to alter the audio spectrum.
Graphic equalizers allow engineers to identify a specific frequency for boost or cut within a fixed frequency bandwidth. A 10-band equalizer enables the audio engineer to adjust 10 specific frequencies, which typically include (in Hz): 31, 63, 125, 250, 500, 1k, 2k, 4k, 8k, and 16k (see figure 3). Graphic equalizers are often one of the final elements of the signal chain preceding only the amplifier and speakers. In this position, they can be used to adjust the overall sound quality of the entire mix.
Implications for the Singer
Equalization can be used in many different ways. When striving to replicate the natural timbre of a voice, a singer should audition several microphones and try to find an option that requires minimal equalization. If they are unable to find a suitable microphone, equalization adjustments can be used to compensate for the microphone’s frequency response curve. If a singer wants to purposely alter the timbre of their voice, equalization is the best place to start. For example, if a singer’s voice lacks forward placement, they could add power to the forward placement zone by boosting the forward placement frequencies with the equalizer. If a singer is sick and the natural ring of his or her voice is missing, they could use equalization to compensate. In both of these situations, equalization can be used to help a singer achieve the results he or she desires without resorting to constriction.
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