A voice-operated gain adjustment device using transistors

Systems involving continuous analysis of speech require that the variations in the input speech signal level be kept to a minimum. This can be achieved by means of a voice operated gain adjustment device (VOGAD). This paper describes the VOGAD which was developed for use with CEERI Vocoder. In its present state, the VOGAD can keep the output level constant within ± 2 dB when the input level varies by ± 20 dB. An additional feature of the VOGAD is its ability to keep the gain at a low value during the pauses in speech. This helps to keep the background noise in between the spoken words at a minimum level.