Post by tolev on Jul 20, 2016 11:37:01 GMT
I've been reading and experimenting with acoustics, especially acoustic absorbers.. Lately, I am experimenting with finding the best absorbers for first reflections.
I've set up speaker and microphone in my backyard. there are no walls within 10m from the measurement location. The speaker is 5inch, controlled directivity monitor, with wide dispersion up to 6khz. Mic is on 1m distance, on height of 1.5m. Then I made measurement without panel, and calculated the comb-filter figure and it was nearly the same as the measured one. Then by placing different panels (rockwool panel, rockwool anechoic wedge) i measured the new fr response.
The small anechoic wedge of height 30cm and width 35cm, was good in first reflection taming, down to 800Hz. The same was with the rockwool panel.
But then when i placed the same height 30cm anechoic wedge but 120cm wide, the first reflection was tamed down to 300Hz, and some residual absorbtion to 100Hz.
I came to the conclusion, that not only the absorber itself, but the surface of the absorber has impact on taming the first reflections.
I haven't read anything like this phenomenon in the literature, though it is logical. What's your opinion on this?
Setup images, without FR response measurements
(http://i44.photobucket.com/albums/f8...pspwitecgc.jpg)
(http://i44.photobucket.com/albums/f8...psyyhegpot.jpg)
(http://i44.photobucket.com/albums/f8...psyl05zdy6.jpg)
I've set up speaker and microphone in my backyard. there are no walls within 10m from the measurement location. The speaker is 5inch, controlled directivity monitor, with wide dispersion up to 6khz. Mic is on 1m distance, on height of 1.5m. Then I made measurement without panel, and calculated the comb-filter figure and it was nearly the same as the measured one. Then by placing different panels (rockwool panel, rockwool anechoic wedge) i measured the new fr response.
The small anechoic wedge of height 30cm and width 35cm, was good in first reflection taming, down to 800Hz. The same was with the rockwool panel.
But then when i placed the same height 30cm anechoic wedge but 120cm wide, the first reflection was tamed down to 300Hz, and some residual absorbtion to 100Hz.
I came to the conclusion, that not only the absorber itself, but the surface of the absorber has impact on taming the first reflections.
I haven't read anything like this phenomenon in the literature, though it is logical. What's your opinion on this?
Setup images, without FR response measurements
(http://i44.photobucket.com/albums/f8...pspwitecgc.jpg)
(http://i44.photobucket.com/albums/f8...psyyhegpot.jpg)
(http://i44.photobucket.com/albums/f8...psyl05zdy6.jpg)
