Resolution in an Artificially Generated Multiple Object Auditory Sensations Space Using New Auditory Sensations

Auditory space, produced by means of a Continuous Transmission Frequency Modulated (C.T.F.M.) wide beam, wide band sonar, has been used in a sensory aid for the blind for some time. Yet, no satisfactory definition of auditory resolution which is directly related to spatial resolution, has been obtained and measured by controlled experiments. In this paper, laboratory experiments, using realistic system simulation techniques are described which determine the ability of subjects to resolve objects in space by auditory means, under both static and dynamic conditions. It is shown that while the auditory frequency resolution is poor under static conditions, it is significantly improved in the dynamic case. The Doppler effect, involving doubling the rate of change of the audio frequency, plays a significant part in this improvement. An increase in relative velocity of an object may also enhance the resolution capability quantitatively as well as qualitatively to an extent that signals may be resolved cognitively before the subject's reaction can take place.