a human head and torso. They consist of acoustic materials fitted with ear and mouth simulators as well as two microphones inserted within each ear canal, typically at the ear drum. Simulated dummy head recording Takes place through the digital signal processing (DSP) where the signal is sent through a complex mathematical algorithm imprinting limited HRTF information creating the binaural effect. This process is called HRTF-based binaural algorithm. Limitations The main focus of recording with a dummy head is to achieve a perfect binaural playback that is suited to all listeners. The problem arises that each human head has different shaped and sized features. Due to the diversity in HRTFs it is impossible to create a binaural effect compatible for everyone’s ears. Therefore the simulated dummy head recording algorithm uses average HRTFs to create a moderate binaural effect for everyone. History The dummy head recording is associated with the use of the physical synthetic head called the “Kunstkopf”. The Kunstkopf would be placed in concert halls during the recording of a live orchestra or in the film industry actors could stand around the head whilst recording their dialogue. The dummy head could also be used to imprint positional information on prerecorded sound effects by playing sounds through a loudspeaker in a suitable orientation to the head. For example thunder and birdsong sounds to be played above the dummy head. During the 1990s, electronic devices which used digital signal processing (DSP) to reproduce HRTFs were made commercially available. These devices would allow the sound engineer to use dialled parameters to adjust the apparent direction of real time sounds. They were unusual and expensive, but would allow the sound engineer to alter special effects of prerecorded sounds quickly and conveniently. Through the manipulation of the parameters, sound engineers could take a monophonic recording of a passing car and make it sound as if it were passing behind them in real time. Recording with an actual dummy head for the same outcome would require a recording booth and a moving speaker, or an array of speakers as well as multiple panning or switching devices. Applications The dummy head manufacturers design their products differently to one another catering for specific situations. The GRAS dummy’s are flexible: they include head or torso with replaceable pinnae of different sizes and materials, set of different type ear-canal simulators, ear-drum simulators. Heads may include or not include mouth