Abstract: The touch dynamics of the operation of keys of an electronic musical instrument are determined through the use of pressure sensitive transducers associated with the keys, the transducers each including a magnetic field responsive semiconductor device and providing signals which are analyzed to determine their variation in magnitude as a function of time. Additionally, after a pre-selected time period, if a key remains operated and the pressure exerted thereon is varied, the output voltage of the key associated transducer will be further analyzed to determine if the player is calling for the reproduction of a secondary effect.