Abstract: Electrical circuitry for varying the relative distinctiveness between the lead and rhythm audio signals produced by an electrical guitar, or the like, according to the strength with which the musician picks the guitar strings. The rhythm signal is compressed in response to how hard the player strums or picks the guitar, while the lead signal is expanded as a direct function of rhythm signal compression. An electrical signal is generated from the rhythm signal for controlling the extent of compression and expansion of the audio signals.

Abstract: A keyboard for a monophonic musical instrument has a plurality of touch sensitive keys which function as variable capacitors, the capacitance depending on the force applied to the keys. The variable capacitance is detected and used to produce a variable control voltage which is used to execute one or several of various control functions, such as controlling the volume of the sound produced by The instrument, controlling the cutoff frequency of a low pass filter in the output system of the instrument, controlling the amount of vibrato or other periodic modulation introduced into the sounds produced by the instrument, controlling the frequency of the vibrato or other periodic modulation, or controlling the amount of "bend" in the pitch of a sound produced by the instrument, i.e. shifting the pitch slightly from its nominal value. The variable capacitors employ a conductive elastomer which is deformed in response to the force applied to the keys.