A transducer comprises transmission means (10) for transmitting ultrasonic energy. The transmission means comprises insulating means and includes a diaphragm portion (11) and an amplifier portion (12). The diaphragm portion has a wave receiving/generating surface (14). Sensor/generator means is coupled to the apex (15) of amplifier portion (12) for sensing/generating ultrasonic energy passing through transmission means (10). The sensor/generator means is insulated by transmission means (10) from exposure to temperature variations.
