[basscleaner]

Hello, to all.
I know from HT practical installations, that it is very important to get right acoustical dimensions for acoustical projecting. This means, that, in particular, ears resolution for low frequencies (20 - 200 Hz) must be taken into consideration to avoid negative resonanсes structure influence. Are there any investigations for such a resolution determinating? To my practice, it equals approximately 3-4 Hz up to 100 Hz and 4-5 Hz up to 200 Hz. But I'm not sure, that such a dependence is constant for any sound pressure levels. Could anybody give me a link for information?
Thanks.

 

[Andre]

An ears "resolution" would entirely depend on the person, therefore any investigation would be skewed. You can, however take measurements using an omnidirectional mic at the primary seating area at head level as an approximation

 

[basscleaner]

Hi, Andre.
My question is not so simple as it seems to be. First of all, it relates to choice of the range between close modal frequencies, because modal frequencies distribution defines the smoothness of AFC (SPL curve) and as a result, the timbre of the room music. If we have mf close to each other, the resonance probability for such a room dimensions grows. Second, we don't talk about any person. We assume, that HT or any other kind of control stereo room is intended for persons with sharp "musical" ears. For this kind of person, I mean, we can define minimal distance between two close frequencies. I never met anybody, who can resolve the difference in 1 Hz between two frequencies.
To my practice, it begins from 20 Hz with interval 3 Hz up to 80 Hz and than 4 Hz to 150 Hz. But unfortunately I never know any investigations in this theme. :-(

 

[Andre]

I would have to point you to someone in academia. Such as the acoustic scientists at the Canadian National Research Council

Peter Hanes
Telephone: 613-998-1282
Email: [email protected]

 

[basscleaner]

Hi, Andre.
Unfortunately, nothing happens with my message to Peter. Probably, he's very busy or hasn't got an opportunity to contacts. I'll be waiting.
Anyway, thank you, Andre, for help.

 

[paulys55]

Earl Geddes would be the guy to answer this one. He is about as good a source as anyone on this topic. Not sure if he looks in on this forum but is definitely on some of the other diy forums. Google is your friend. Good luck.

 

[basscleaner]

Returning to the question, which has been asked for, I've found the answer in the russian book "Acoustics" by Vahitov, Kovalgin Fadeev and Schelgin on the page 123. This dependence looks like hyperbolic and grows from 1.8 Hz for frequencies before 500 Hz higher than 50 Hz for 6 kHz.
This means, that minimum distances between modes must be no less, than 2-3 Hz for acoustical comfort in HT and stereo control rooms.