Distance hearing
The removal hearing is estimating determination with the hearing how far a sound source from the listener is removed.
In contrast to the particularly well developed ability of binocular distance vision , the human ear can only poorly determine the distance to a sound source. With distance hearing, the signal differences are not used, i.e. the level and transit time differences between the two sensors , but the comparison of the signal with learned stimulus patterns :
- Spectral distribution: High frequencies are more strongly absorbed by the air than low frequencies . Therefore, the spectrum is changed depending on the distance to the sound source. The sound event sounds duller with increasing distance, so that in the case of known sound events we can infer the distance from the change in their sound character. At the same time, low frequencies on obstacles or, for example, already on the bell of a wind instrument are bent more than high frequencies, so the bass component (a directed sound source) also decreases.
- Loudness : Sound sources further away have a lower volume than closerones. This aspect can only be used with familiar sound sources such as speaking people.
- Direct sound component: The sound pressure level of the direct sound decreases linearly with distance, but that of the diffuse sound remains almost constant in a reflecting environment, so that this ratio changes significantly with the distance from the sound source. That is why it is one of the most important features of distance hearing, linked to optical perception.
- Initial gap : With distant sound sources, the first strong reflections hardly have a longer way to the listener than the direct wave. They therefore arrive at him almost at the same time, while with a nearby sound source there is a clear gap in the beginning due to the various detours. Their great importance for the spatial staggering of the sound field isoften neglectedin sound productions .
- Movement information: Similar to the visual system, there is the phenomenon of movement parallax : When we move, closer sound sources pass us faster than distant ones.
- Interaural level differences : They play a role above all with very close sound sources. If the sound reaches one ear much louder than the other, we can conclude from our listening experience that this sound source must be very close.
The distance estimate in the open field , i.e. without reflections and echoes , depends primarily on the volume perception. If the sound is known, the sound pressure level is compared to a value stored in memory and the distance is “calculated”. Hearing from a distance is therefore based on learned knowledge, and perception is significantly influenced by experience .
Increasingly, however, the realization is also gaining ground that the temporal and spatial staggering of the first high-sound reflections has an outstanding influence on the auditory distance perception.
