Sound localization

The distance hearing is an evaluative determination by hearing how far a sound source is removed from the hearing.

In contrast to the very well-trained ability of the binocular distance vision, the ear of man can only legally deficient determine the distance to a sound source. The difference signal, ie, the level difference and the propagation time differences between the two sensors are not used when listening for distance determination, but for determining the direction. For distance hearing, therefore, the comparison of the signal with learned stimulus patterns must be used:

• Spectral distribution: high frequencies are more absorbed by the air as deep. Therefore, the range as a function of the distance is changed to the sound source. The sound event sounds less with increasing distance, so that we can conclude from the change in their sound character to the distance in the known sound events. At the same low frequencies around obstacles or, for example, already on the bell of a wind instrument are more bent than high frequencies, so does also the amount of bass ( a directional sound source) from.
• Loudness: More distant sound sources have a lower volume than more. This aspect can only be used with the familiar sound sources such as speaking people.
• Proportion of direct sound: The sound pressure level of the direct sound decreases linearly with distance. In reflecting environment, however, the diffuse sound level remains approximately constant, so that this ratio varies strongly with the distance of the sound source. Therefore, it is linked with the optical perception, one of the most important features in distance hearing.
• Initial time gap: distant sound sources, the first reflections have little a longer path to the listener than the direct wave. Therefore meet almost simultaneously at him while at a nearby sound source through the various detours a significant initial time gap. Their importance for the spatial positioning of the sound field is often neglected in sound production.
• Motion information: Similar to the visual system, there is the phenomenon of motion parallax: If we move, then pull more sound sources faster than more distant past us.
• Interaural level differences: They play a role especially in very close sound sources. Achieved the sound an ear much louder than the other, so we can conclude from our listening experience that this sound source must be very close.

The distance estimation in the open field, without reflections and echoes, depends primarily on the perception of loudness. If it is a known tone, the sound pressure level is compared with a value stored in memory, and " calculated " distance. Distance hearing based on learned knowledge. The perception is strongly influenced by past experience. Increasingly, however, is made by the finding that the temporal and spatial staggering of the first reflections has outstanding impact on the auditory distance perception.