An apparatus and a method for generating ultrasound are provided. The apparatus comprises a signal generator arranged to generate a driving signal and an ultrasound transducer arranged to transmit an ultrasound beam in response to the driving signal. The signal generator is arranged to combine a carrier wave 202 and a modulating wave 200 having a lower frequency than the carrier wave, to generate an amplitude-modulated driving signal 204. The ultrasound beam is suitable for inducing cavitation in a human or animal body tissue. The beam may be a continuous beam as part of a high-intensity focused ultrasound system, and the modulated beam is more closely controllable than through frequency mixing.
