Sound engineer to make a good sound necessary professional knowledge four: Haas effect

Haas found in his experiments that if two different sound sources produce the same sound and reach the audience at the same time with the same intensity, the subjective perception is that the sound comes from between the two sound sources; if

One is slightly delayed (about 5 to 35 milliseconds), it sounds like both sounds are from the undelayed sound source, the existence of the delayed sound source has no effect on the orientation, but increases the loudness; If the delay is 35 to 50 millimetres

Between seconds, the existence of the delayed sound source can be identified, but its direction is still in the direction of the undelayed sound source; Only when the delay exceeds 50 milliseconds is the second sound source heard like a clear echo.

It can be seen that if two identical sounds appear within 50 milliseconds (1/210 seconds), it is generally not distinguishable, and only changes in timbre and loudness can be detected if the second sound is delayed

Come back 50 milliseconds later, and with enough loudness, we can tell them apart. This effect is applied to indoor PA systems, which can ensure listeners in the sound field of distributed speaker systems

Visual and auditory coherence.

In the hall, if the acoustic distance difference between the reflected sound and the direct sound is greater than 17 meters, and the sound absorption effect of the room is not good, it will produce echoes, thus destroying the naturalness and intelligibility of the language. Also, in the larger hall

In order to ensure the uniformity of the sound field, auxiliary speakers are often provided in the back field, and at this time, for the audience sitting in the back row, if the distance from the main speaker to him is 12 larger than the distance from the auxiliary speaker to him

Meters (equivalent to the sound delay of 35 milliseconds from the main speaker than the sound from the auxiliary speaker in the back), he will feel that the sound is coming from the back, at this time, in order to ensure that the audience's visual and auditory consistency must be given

The rear auxiliary speaker is equipped with a delay device. It should also be noted that we always assume that the volume of the two sound sources is the same, and in fact, if the delay does not exceed 20 to 30 milliseconds, you can lead by attenuation

The volume of the sound channel (or increase the volume of the lagging sound channel) to change the position of the sound image.