Human lymphocytes were sonicated "in vitro" with short acoustical repetitive pulses, produced by a diagnostical transducer, either driven by capacitor discharge devices or by burst generators. Different biological effects were found, supported also by experimental data on pure cytochrome c reduction. Such effects prompt us to hypothesize the presence, in the acoustical pulses produced by the trasducer, of high frequency components hard to detect because of the difficulty to obtain precisely the electroacoustical transfer function of the commonly employed receiving transducers
