Franssen effect

With Franssen effect, the observation is described that in reverberant environment is a localization of sound sources is only possible if there are more changes in the acoustic signal and that once a certain direction is assumed as long as Hörereignisrichtung until a directional information can be evaluated.

Attempt

This effect can be illustrated by the following listening test:

Explanation

Background for this behavior is that, outside of the reverberation radius the volume of the reflected sound from the chamber walls is substantially greater than the direct sound of the speakers. Thus acts in the steady state of the room sound from all possible directions in space at the same time on the listener, a direction can not be determined from this.

Only at the beginning of the experiment, when the right speaker is turned on, there is a short period in which the direction can be determined, namely when already the direct sound arrives at the listener, the sound from the wall reflections but not yet. This time appears to use the sense of hearing to determine the direction of incidence of the sound. And this direction seems to be the hearing so long maintained until re- direction information is evaluated.

During the gentle cross-fading between the speakers predominates at all time points, the reflected sound from all directions, the direct sound; the ear is not able to determine a direction of incidence. Therefore, even after the fade and disconnecting the cable the auditory event remains at the position of the right speaker.

Only when there are larger signal differences again, so that in the short term the direct sound can outweigh the reflected sound, the hearing may determine a reliable sound incidence direction again and then arranges the sound until further this direction.

• Psychoacoustics
• Surround sound
• Beschallungstechnik