Scott,
> knowing the "theoretical" modal content of room can help a great deal in analysis. <
How so? What would someone do differently in treating their room knowing the predicted modes versus simply measuring the response and ringing? I'm not convinced measuring is all that useful either since as I said earlier the solution is the same regardless. And I measure rooms for a living!
I'm sure you recall the thread at RO where I showed that the measured mode frequencies were off by as much as 20 percent from what was predicted for the RealTraps lab. So I don't see a whole lot of value in running a mode calculation on a room whose dimensions won't be changed. But if you'd care to elaborate on how someone could use those calculations - specifically - I'll be glad to listen and learn. BTW, my showing the extreme disparity between predicted versus measured modes is yet another example of "theory" often missing the forest for the trees. Indeed, if knowing the room's state ahead of time is valuable at all, it's the
measured response I care about, not a prediction that may or may not even be close to reality.
> In doing such as that - its nice to have ability to look at the entire calculable modal content - thus calculators that go beyond simply the structure of the axials should be used ...
http://www.bobgolds.com/Mode/RoomModes.htm <
I agree - Bob made a neat program there. But I find all that data very confusing. I just entered the dimensions for the RealTraps test lab, and Bob's program spit out 80 modes! (Listed in the table below.) What the is someone who is not a professional acoustician supposed to do with all that data? , what is a
professional acoustician supposed to do with all that data? Build 80 different tuned bass traps? I am serious! What do you do with all that data? How do you distinguish which modes matter a lot and which modes don't matter as much or even at all?
More to the point, how do you get from that list of modes to an effective treatment solution for a basement home theater or bedroom project studio?
--Ethan
Quote:
Frequency hz Spacing % Wavelength 1/2 Wavelength 1/4 Wavelength p q r Mode
34.9 32'5" 16'2" 8'1" 1 0 0 Axial
49.0 28.7 23'1" 11'6" 5'9" 0 1 0 Axial
60.1 18.4 18'10" 9'5" 4'8" 1 1 0 Tangential
69.9 14 16'2" 8'1" 4'0" 2 0 0 Axial
70.6 0.9 16'0" 8'0" 4'0" 0 0 1 Axial
78.8 10.4 14'4" 7'2" 3'7" 1 0 1 Tangential
85.3 7.6 13'3" 6'7" 3'4" 2 1 0 Tangential
85.9 0.6 13'2" 6'7" 3'3" 0 1 1 Tangential
92.8 7.4 12'2" 6'1" 3'1" 1 1 1 Oblique
97.9 5.2 11'7" 5'9" 2'11" 0 2 0 Axial
99.4 1.5 11'4" 5'8" 2'10" 2 0 1 Tangential
104.0 4.4 10'10" 5'5" 2'9" 1 2 0 Tangential
104.8 0.7 10'9" 5'5" 2'8" 3 0 0 Axial
110.8 5.4 10'2" 5'1" 2'7" 2 1 1 Oblique
115.7 4.2 9'9" 4'11" 2'5" 3 1 0 Tangential
120.3 3.8 9'5" 4'8" 2'4" 2 2 0 Tangential
120.7 0.3 9'4" 4'8" 2'4" 0 2 1 Tangential
125.7 3.9 8'12" 4'6" 2'3" 1 2 1 Oblique
126.4 0.5 8'11" 4'6" 2'3" 3 0 1 Tangential
135.5 6.7 8'4" 4'2" 2'1" 3 1 1 Oblique
139.5 2.8 8'1" 4'1" 2'0" 2 2 1 Oblique
139.8 0.2 8'1" 4'0" 2'0" 4 0 0 Axial
141.3 1 7'12" 3'12" 1'12" 0 0 2 Axial
143.4 1.4 7'11" 3'11" 1'12" 3 2 0 Tangential
145.5 1.4 7'9" 3'11" 1'11" 1 0 2 Tangential
146.9 0.9 7'8" 3'10" 1'11" 0 3 0 Axial
148.1 0.8 7'8" 3'10" 1'11" 4 1 0 Tangential
149.5 0.9 7'7" 3'9" 1'11" 0 1 2 Tangential
151.0 0.9 7'6" 3'9" 1'10" 1 3 0 Tangential
153.5 1.6 7'4" 3'8" 1'10" 1 1 2 Oblique
156.6 1.9 7'3" 3'7" 1'10" 4 0 1 Tangential
157.6 0.6 7'2" 3'7" 1'10" 2 0 2 Tangential
159.9 1.4 7'1" 3'6" 1'9" 3 2 1 Oblique
162.7 1.7 6'11" 3'6" 1'9" 2 3 0 Tangential
163.0 0.1 6'11" 3'6" 1'9" 0 3 1 Tangential
164.1 0.6 6'11" 3'5" 1'9" 4 1 1 Oblique
165.0 0.5 6'10" 3'5" 1'9" 2 1 2 Oblique
166.7 1 6'9" 3'5" 1'8" 1 3 1 Oblique
170.7 2.3 6'7" 3'4" 1'8" 4 2 0 Tangential
171.9 0.6 6'7" 3'3" 1'8" 0 2 2 Tangential
174.7 1.6 6'6" 3'3" 1'7" 5 0 0 Axial
175.4 0.3 6'5" 3'3" 1'7" 1 2 2 Oblique
175.9 0.2 6'5" 3'3" 1'7" 3 0 2 Tangential
177.3 0.7 6'4" 3'2" 1'7" 2 3 1 Oblique
180.4 1.7 6'3" 3'2" 1'7" 3 3 0 Tangential
181.4 0.5 6'3" 3'1" 1'7" 5 1 0 Tangential
182.6 0.6 6'2" 3'1" 1'7" 3 1 2 Oblique
184.7 1.1 6'1" 3'1" 1'6" 4 2 1 Oblique
185.5 0.4 6'1" 3'1" 1'6" 2 2 2 Oblique
188.4 1.5 5'12" 2'12" 1'6" 5 0 1 Tangential
193.8 2.7 5'10" 2'11" 1'5" 3 3 1 Oblique
194.7 0.4 5'10" 2'11" 1'5" 5 1 1 Oblique
195.8 0.5 5'9" 2'11" 1'5" 0 4 0 Axial
198.7 1.4 5'8" 2'10" 1'5" 4 0 2 Tangential
198.9 0.1 5'8" 2'10" 1'5" 1 4 0 Tangential
200.3 0.6 5'8" 2'10" 1'5" 5 2 0 Tangential
201.3 0.4 5'7" 2'10" 1'5" 3 2 2 Oblique
202.8 0.7 5'7" 2'9" 1'5" 4 3 0 Tangential
203.8 0.4 5'7" 2'9" 1'5" 0 3 2 Tangential
204.7 0.4 5'6" 2'9" 1'5" 4 1 2 Oblique
206.8 1 5'6" 2'9" 1'4" 1 3 2 Oblique
207.9 0.5 5'5" 2'9" 1'4" 2 4 0 Tangential
208.2 0.1 5'5" 2'9" 1'4" 0 4 1 Tangential
209.6 0.6 5'5" 2'8" 1'4" 6 0 0 Axial
211.1 0.7 5'4" 2'8" 1'4" 1 4 1 Oblique
211.9 0.3 5'4" 2'8" 1'4" 0 0 3 Axial
212.4 0.2 5'4" 2'8" 1'4" 5 2 1 Oblique
214.7 1 5'3" 2'8" 1'4" 1 0 3 Tangential
214.7 0 5'3" 2'8" 1'4" 4 3 1 Oblique
215.3 0.2 5'3" 2'7" 1'4" 6 1 0 Tangential
215.4 0 5'3" 2'7" 1'4" 2 3 2 Oblique
217.5 0.9 5'2" 2'7" 1'4" 0 1 3 Tangential
219.6 0.9 5'2" 2'7" 1'3" 2 4 1 Oblique
220.2 0.2 5'2" 2'7" 1'3" 1 1 3 Oblique
221.2 0.4 5'1" 2'7" 1'3" 6 0 1 Tangential
221.5 0.1 5'1" 2'7" 1'3" 4 2 2 Oblique
222.1 0.2 5'1" 2'7" 1'3" 3 4 0 Tangential
223.1 0.4 5'1" 2'6" 1'3" 2 0 3 Tangential
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