Acoustic Center

[jsa_ind]

In a Line array of four 10 inch woofers, how does one find the "Acoustic Center" of the Line array?
Is there any software that can either model the "Acoustic Center" or physically calculate the same?

Thanks for your inputs in advance!

jsa_ind

[gedlee]

The whole concept of "acoustic center" was abandoned by the Standards group of AES several years ago because it could not be defined unambiguously. Basically there are a great many situation where the so-called "Acoustic center" is moving all over the place. There is no single place that can be called the "center".

Better is to think of excess group delay from some given point. In this case it doesn't matter where that point is so long as its fixed in space.

[jsa_ind]

Thank you Sir for the quick response!
Could you please advise how does one calculate the "Excess group delay" from a given point when it comes to a line array of four woofers?
Thank you!
jsa_ind

[gedlee]

I believe that most measurement software will do that.

Group delay is the rate of change of phase with frequency. There is going to be a "mean delay" which is as close to the "acoustic center" concept as you will get, and there will be variation from this mean which can be called the "excess group delay". This will tell you how stable the acoustic center is with frequency. In general one wants the excess group delay to be small, in which case there actually is a clearly defined acoustic center, but in practice there will always be some excess group delay and hence an ambiguous location for the acoustic center. Line sources will defintely have a large excess group delay by their very nature.

[jsa_ind]

Thank you Dr. Geddes for all your inputs!

jsa_ind