During the last decade the binaural technique has been used increasingly for recordings of noise and music. The main reason is the capability of the technique to store and reproduce three-dimensional aspects of a sound field by means of only twochannels.The idea behind the binaural technique is the following. The input to the hearing consists of two signals - the sound pressures at each of the eardrums. If these are recorded in the ears of a listener and reproduced exactly as they were (usually throughheadphones), then the complete auditory impression is recreated, including spatial aspects such as direction and distance to sound sources. In most practical applications recordings cannot be made in the listener's own ears, and during recording the listener is usually replaced by a copy of a human head, called an artificial head or a dummy head. Several artificial heads are commerciallyavailable, and they do produce recordings with a surprisingly natural reproduction. Nevertheless, it is often claimed that the three-dimensional space is distorted, and that localization errors occur. Often mentioned imperfections are: Confusions betweenfront and back, elevation of sound sources, sound sources perceived too close, and in-the-head localization. These shortcomings have mainly been observed in rather informal listening tests, and their existence has not been proven in large-scale scientific experiments. Nevertheless, it is generally accepted that the imperfections do exist, and this fact seems to limit the success of the artificial head recording technique. It was therefore the purpose of this investigation (presented in more details in [1]) to study the quality of artificial head recordings. Note that the investigation thus constitutes anevaluation of the binaural technique when the recordings are made with artificial heads. We have previously carried out similar evaluations of the technique with recordings made in human ears [3], [4].
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