What is the effective distance range of the acoustics diffuser?

[MengW]

Hello,

In one local DIY studio video, he said that there are the effective distance range of the diffuser. It's no effective if the distance less than 2 meter from the speaker to the diffuser.

It's the new knowledge and interesting to me.

I tried to search the related information.

1.From this page.

Sound Diffuser Placement - How To Position A Sound Diffuser – Acoustic Fields

Today we're going to talk about ideal sound diffuser placement and where to position your sound diffuser for your particular room usage.

www.acousticfields.com

Let’s use 250 Hz. as our example. A 250 cycle ray of energy is almost 5′ long. If we divide the speed of sound by the frequency 250, we ~ 4 feet. If the well or trough depth is at a quarter wavelength then we need 12″ of well depth at 250 Hz. With a four feet long ray of energy, we need at least 4′ of distance from the diffuser to the listening position to hear the fill 250 cycles of energy. You actually need twice that distance. You need twice the distance so you achieve two full 4′ oscillations.

2.The classical video, all about diffusion from Ethan Winer
4:12, diffusers are usually placed at least 6~10 feet away from instrument, mic and listener. aim to make the artifacts too soft to notice.

Is there any research papers or reference materials for the diffuser effective distance?

Thanks a lot.

Meng

 

[ozzy9832001]

I could be completely wrong, but I haven't seen to many diffusors advertised for less than 500hz. Absorption still is the best option to handle those frequencies. Absorption is thick enough to handle that and it has other benefits with standing waves, reflections and resonances. I know the bass traps and panels I bought from GIK were all tuned to reflect any frequencies above 500hz, as I didn't want the room over absorbed.

From my point of view, I don't see any benefit for LF diffusion over absorption. The key with the LF is to take the pressure and energy out of the room not disperse it.

 

[MengW]

I could be completely wrong, but I haven't seen to many diffusors advertised for less than 500hz. Absorption still is the best option to handle those frequencies. Absorption is thick enough to handle that and it has other benefits with standing waves, reflections and resonances. I know the bass traps and panels I bought from GIK were all tuned to reflect any frequencies above 500hz, as I didn't want the room over absorbed.

From my point of view, I don't see any benefit for LF diffusion over absorption. The key with the LF is to take the pressure and energy out of the room not disperse it.

Got it! Thanks for your reply, I agree very much.

In the past three years, I have mainly used AVAA to decay low-frequency energy, and I am very satisfied (except for the price). And used some polyester + perforated acoustic panels/wood strips as covering, to deal with early reflections.

Diffusers seem familiar to me but not yet understood, so I want to know more about it by some books or research papers.

Btw, in my impression, I have seen this expression and comparison before.
After the diffuser is used to disperse the sound, the energy is more absorbed by the absorber, and the reverberation time of the mid-to-high frequency is a little lower.

Btw, this metamaterial diffuser is still very interesting, but it should still be in the lab.

Metadiffusers: Deep-subwavelength sound diffusers - Scientific Reports

We present deep-subwavelength diffusing surfaces based on acoustic metamaterials, namely metadiffusers. These sound diffusers are rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Strong dispersion is produced in the slits and slow sound conditions...

www.nature.com