Speaker perforations

[MehdiZerrad]

Hello everybody,

Is there someone who has a physical explanation about the impact of the perforations in the speakers plate, on the sound pression field ??
What is te correlation between the density of perforations and wave lenght ?

Thank you

 

[GregLocock]

Can you link to a photo of the feature you are talking about?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[MehdiZerrad]

Thank you for your reactivity,

This link contains some pictures of what i am talking about :

https://www.google.fr/search?q=gril...h&sa=X&ei=b_J-U7TyF-ic0AWy8IGQCw&ved=0CAUQ_AU

Cheers

 

[GregLocock]

OK, that's called a speaker grill. I'm afraid I have no experience of measuring or calculating the effect of these. gut feel is that it would affect high frequencies, particularly where wavelength is approximately the same as the grill apertures, say 3 mm, say 100000 Hz.

However they also act as mini Helmholtz resonators, and there is also the possibility of mass loading coupling between the air and the grill. It's a complex subject.

Here's some measurements, I'm not going to lose any sleep over 1 dB

http://www.rjbaudio.com/Audiofiles/grill frame diffraction.html

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[MehdiZerrad]

Thank's Greg for your help its really nice of you.

 

[rob768]

I'm guessing its just protection, but as they seem to be able to come off easily, I suggest listening or measuring a sample (pink noise?) with and without them.

 

[MehdiZerrad]

Thank you rob768 for your answer.

Actually it's clear that people use this grille for the protection of the loudspeaker, but what i want to understand is the impact of this feature on the sound pressure level, among large band frequencies.
Otherwise, i'm planning to pick up some measures in order to clarify that.

 

[rob768]

then measuring with pink noise would be the best option