Hi listed members...
About the anechoic chamber, I remember to saw such a large room described from a loudspeaker maker. Unfortunately, I could not find which one in my archived documents. They were concerned about low frequencies also, but I do not think that size of wedges really matters at low frequencies (80 Hz and below).
At that room, if my memories still clear, those pictures did show their wedges measure about 15 inches long, some longer some shorter but it was not aimed to absorb lows...
I think a carefull designed room, takes account for avoiding modal dimensions at low frequencies and isolate the room from external vibrations from outside building surface sources (like trucks, trains, amplified vibes from bridges, etc..) suspending the great box in some manner...
I wish I could take part in such project as so much knowledge would be involved and developed... ;-)
Regards to all.
2008/10/15 Peter Lennox <P.Lennox@xxxxxxxxxxx>
I've a feeling that the only people with such large anechoic rooms will be military, so whether their output is accesible, I don't know
Dr Peter Lennox
Director of Signal Processing and Applications Research Group (SPARG)
School of Technology,
Faculty of Arts, design and Technology
University of Derby, UK
t: 01332 593155
From: AUDITORY - Research in Auditory Perception [AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Chuping Liu [tracy_liu_99@xxxxxxxxx]
Sent: 15 October 2008 07:37
Subject: accuracy of loudspeaker measurement in anechoic chamber: dimension and absorber
When loudspeaker is measured in anechoic chamber, for valid results at low frequencies, it means large anechoic chamber and large absorbent wedges. I found quite some literature discussing the accuracy of loudspeaker measurement in terms of different wedges. Yet I haven't found any literature talking about the measurement accuracy (in terms of frequency extend and errors) regarding the physical dimensions of the anechoic chamber, or ideally for both of chamber dimensions and absorber characteristics.
If anyone is aware of the existence of such literature, I would appreciate to be pointed out. Thanks.