About Us

You may have noticed the introduction of two new characters at AMS Acoustics. Although Ed (the head) and his sister Edwina have been with the company for a good number of years, it has been decided that due to their impeccable standard of electro-acoustic related works they should become our company mascots. Designed and manufactured by Bruel and Kjaer, Ed and Edwina are Head and Torso Simulators (HATS) Type 4128C and 4158C respectively, each consisting of a head mounted on a torso, which represent the international average dimensions of a human adult. In airborne acoustic measurements they provide the correct simulation of the acoustic field around a human head and torso. Both can be used free standing, fitted on a tripod, or on a turntable using the tripod mounting adaptor. 


Ear Simulator Type 4158C consists of a removable silicon-rubber pinna joined to an ear canal. The ear canal ends in an occluded ear simulator which simulates the inner part of the ear canal according to the IEC 60711 standard. The occluded ear simulator contains a ½" microphone and is connected to a microphone preamplifier with an adaptor. The ear simulator complies with ITU-T Rec. P.57. Type 4158C is the right ear of Type 4128C. A left ear, Type 4159C, is also available for binaural measurements. For headphone measurements, soft pinnas are also available. Both Type 4158C and Type 4159C are delivered with a calibration chart specific to their ear simulator and pinna. Pistonphone Type 4228 and Sound Level Calibrator Type 228 4231 are both suitable calibrators for these ear simulators. The combined influence of the torso, head, pinna and ear-canal on airborne sound signals can be quantified by the acoustic freefield transfer function (the frequency response from free-field to the eardrum). This is called the Listener free-field frequency response (lfr) in telecommunications work and the Mannequin frequency response in technical audiology.