[music-dsp] Re: Directivity Index

Infos - Bien Entendu infos at bienentendu.fr
Wed Jan 21 01:01:01 EST 2004

no, the average should be made on the whole set of values
measured including the 0 degree value (which is a part of the total
energy send by the source (or received by the microphone)
but don't forget that the ratio for the directivity factor (Q) has to be
made with square pressure (P^2)
and than you make a 10*log Q for the DI
>1. I need to calculate Directivity Index (DI) from a polar plot, ie. I have
>x1 at 0 degrees, x2 at 15 degrees, x3 at 30 degrees and so on... and need a
>means of calculating the DI from this data.  If I want the DI with respect
>to 0 degrees (directly in front) is it simply a ratio of that value (x1)
>divided by a average of all the other values (ie. x1,x2,x3...)?

Pascal Luquet

Bien Entendu
34, rue Etienne Marey
75020 Paris
Tel. 33 1 40 31 56 31
Fax. 33 1 40 31 56 32
eMail : Luquet at BienEntendu.fr

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