I am hoping to instigate a discusion and possibly help others and of course myself out in the process. I am working on wedding hall that needs reduced reverberation times. Just so the thread doesn't attract basic answers I am not an amatuer(apologies for blowing my own trumpet) and know enough about small room acoustics at the very least I think I do and that this thread would rather serve as a guidance, discussion, and a solid platform for larger room venue type acoustics which might have been missed in small room acoustics conversations. Although this all also depends if there is a major discrepancy between the fundamentals of small room acoustics compared to that of larger venues but I am sure there is an overlapp.
The hall is 3000m3 23m from left to right and 17m front to back. The ceiling is a vaulted ceiling which tappers up to about 9m and starts from the stage at around 5m.
1. What is the most effective absorber for the lowest frequencies? 30cm thick fibreglass still doesn't seem to cut it on a pourous calculator. Perhaps a diaphragmatic absorber? I know its easy enough to check on a calculator but does anyone have sold experience, cause I have a back wall with a small portion 2 metre wide and 9 metre high 30cm thick and wondering how to utilise it. I know everyone will say soft fluffy stuff but how about some type of absorber like diaphraghmatic mentioned in Acoustic fields? https://www.acousticfields.com/how-to-build-a-diaphragmatic-absorber/
2. I have heard of the software Ease but are there any other free programs that can help with modelling and simulation for venue acoustics, prefeably something easy if it exists. Or do I just have to stick with a percentage rule if I don't have software. Of course I will measure but what do I use as the starting point to understand how much absorbtion according to what RT60...?
4. Another technique is tuned bass traps but is there a simple way to work out how much bass trapping you need and how much tuned bass trapping you need compered to a 4inch thick panel? Again is there a way to work this out or do I have to add and test as I go along?
3. Room modes occur less in larger rooms but would 4 sub woofers in corners still help to flatten out bass or provide any other advantage? There still will be SBIR from the floor and back wall so that also needs to be tackled right?
5. My understanding for larger rooms the detrimental early reflections are at about 30ms, and larger rooms have this issue much less due to the later arrival times. Griesenger mentions Lateral reflected energy in the 10ms to 50ms range reduces the “closeness” of the sound image • While this perception is pleasant, it is not musically essential. • too much energy in this time range can cause image broadening, timbre coloration, etc. • The ideal is to have the total energy in this time range two to four times less than the direct sound.
Then he goes on to say reflections between 50ms and 150ms are maximullly disturbing and saying reflections after 150ms add to envelopment. Now, I know he mainly works on opera and concert hall, and my application is a wedding hall so I would prefer lower reverberation times with a closer EDT to the RT60(while opera halls would need a longer gap between EDT and RT60 to increase envelopment). I just can't get my head around how you would reduce reverberation while reducing energy in that mid range ms. Any opinions?
6. "As a rule of thumb, sound is delayed 1 mS for every 34 cm of travel." I read this from a website.
Can I use this statement to give me rough idea of at least how long it will take for the direct sound to get to the specific wall, which will essentially let me know after what ms it will arrive to the listerner(of coure all different depending on where they are sitting or dancing)
The hall is 3000m3 23m from left to right and 17m front to back. The ceiling is a vaulted ceiling which tappers up to about 9m and starts from the stage at around 5m.
1. What is the most effective absorber for the lowest frequencies? 30cm thick fibreglass still doesn't seem to cut it on a pourous calculator. Perhaps a diaphragmatic absorber? I know its easy enough to check on a calculator but does anyone have sold experience, cause I have a back wall with a small portion 2 metre wide and 9 metre high 30cm thick and wondering how to utilise it. I know everyone will say soft fluffy stuff but how about some type of absorber like diaphraghmatic mentioned in Acoustic fields? https://www.acousticfields.com/how-to-build-a-diaphragmatic-absorber/
2. I have heard of the software Ease but are there any other free programs that can help with modelling and simulation for venue acoustics, prefeably something easy if it exists. Or do I just have to stick with a percentage rule if I don't have software. Of course I will measure but what do I use as the starting point to understand how much absorbtion according to what RT60...?
4. Another technique is tuned bass traps but is there a simple way to work out how much bass trapping you need and how much tuned bass trapping you need compered to a 4inch thick panel? Again is there a way to work this out or do I have to add and test as I go along?
3. Room modes occur less in larger rooms but would 4 sub woofers in corners still help to flatten out bass or provide any other advantage? There still will be SBIR from the floor and back wall so that also needs to be tackled right?
5. My understanding for larger rooms the detrimental early reflections are at about 30ms, and larger rooms have this issue much less due to the later arrival times. Griesenger mentions Lateral reflected energy in the 10ms to 50ms range reduces the “closeness” of the sound image • While this perception is pleasant, it is not musically essential. • too much energy in this time range can cause image broadening, timbre coloration, etc. • The ideal is to have the total energy in this time range two to four times less than the direct sound.
Then he goes on to say reflections between 50ms and 150ms are maximullly disturbing and saying reflections after 150ms add to envelopment. Now, I know he mainly works on opera and concert hall, and my application is a wedding hall so I would prefer lower reverberation times with a closer EDT to the RT60(while opera halls would need a longer gap between EDT and RT60 to increase envelopment). I just can't get my head around how you would reduce reverberation while reducing energy in that mid range ms. Any opinions?
6. "As a rule of thumb, sound is delayed 1 mS for every 34 cm of travel." I read this from a website.
Can I use this statement to give me rough idea of at least how long it will take for the direct sound to get to the specific wall, which will essentially let me know after what ms it will arrive to the listerner(of coure all different depending on where they are sitting or dancing)
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