The frequency in the middle of a BAND of frequencies, by which the band is identified together with the BANDWIDTH.
For instance, in the standard octave band from 177 to 354 Hz, the centre frequency is 250 Hz. See chart under SOUND ANALYSER, diagram under FILTER and Appendix E.
In electronic SOUND SYNTHESIS, it refers to the frequency of the unmodulated CARRIER signal or the middle of the frequency range to which EQUALIZATION is applied.
See: FILTER, FORMANT, SOUND SYNTHESIZER.