Source resolution in p-p sound intensity method

[jeyaselvan]

I am trying to understand the limits in resolving two sources (located say within the acoustic wavelength). If we assume that the sources independently generate acoustic waves of say 100Hz & 150Hz is it really possible to decipher the sources with p-p sound intensity method?

I am sure that your experience on p-p intensity based source identification will be of great help to me.

I do understand that the phase mismatch of the microphones has an effect on the lower frequencies, but for the sake of argument,may be we can assume they are perfectly matched.

Thanks in advance

 

[IRstuff]

Not sure what you mean by "p-p sound intensity method" but there certainly are algorithms that can resolve source locations, such as MUSIC.

TTFN

FAQ731-376

 

[SomptingGuy]

I guess p-p sound intensity means the two microphone technique, where you use the imaginary part of the crosspower to estimate intensity. Don't really understand the main part of the question thouh :-(

- Steve

 

[jeyaselvan]

Thanks in advance

p-p indicates the pressure-pressure based method (two microphones matched for amplitude and phase, typically B&K's intensity probe).

Since there are currently p-u meaning the pressure-velocity based method, typically the ones from Microflown.

Intensity being the product of sound pressure and particle velocity, in the p-p method, I believe the particle velocity is calculated through cross correlation between the two pressure signals and in the p-u method, it is directly measured through hot wire based methods.

Iam interested in knowing the resolving capability of sources through p-p method when the sources are located in distances much lesser than the acoustic wavelength .

 

[IRstuff]

Resolution is not really an issue with the separation of sources, but rather the resolution, hence, separation, of your detectors. You could have sources separated by multiple wavelengths, but if your microphones are physically next to each other, you'd be unable to resolve where any source is.

By your problem statement, since each source is completely independent, there is no interference, and hypothetically, their separation is irrelevant.

TTFN

FAQ731-376

 

[jeyaselvan]

Thanks IRstuff

I think I have not clearly stated my problem or I have not understood the problem fully.

From the source identification point of view, I am trying to understand whether I would be able to resolve and identify the existence of these sources (and then go for estimating the sound power and so on)using p-p method.

You may find enclosed the comparison of the resolving capability of the various source identification methods ( direct intensity nased and array based). The direct intensity that is mentioned in the attachment corresponds to that of the p-u probe.

I am primarily interested in the lower frequency range, say (200 - 2000Hz).