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.
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.
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.
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.
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