Angling Reflection Panels Post ETC eval

[MyPutzyRod]

Having used ETC to find the proper location of the first significant reflection, how do I most accurately generate the proper angle to shoot the reflection to the back of the room avoiding my listening position?

I may actually try to shoot the reflection to yet another reflector, and THEN to a diffusor, so things need to be precise.

All methods welcome, as I like to try as many as possible to confirm Im doing it correct!

[RhOdEz]

few simple mirrors ?

[MyPutzyRod]

Originally Posted by RhOdEz

few simple mirrors ?

And then do I stand at the position I would like to receive the reflection, placing a mirror at the origin of reflection, and then angle it until I see myself? Obviously this process is a little different as compared to locating primary reflection points.

Thanks for the reply!

[SAC]

The angle of incidence equals the angle of reflection.

An issue here may be that you might be elevating an attribute to a result.

This is tool that can be used in conjunction with a larger acoustic model as well as a larger more comprehensive plan.

Thus to do this requires the modification of the boundary orientation either through basic wall design (as in the Reflection Free model) or by the use of large reflective boundaries - well, as in the Reflection Free model.

If you intend to try this redirection multiple times, be aware of energy loss due to air resistance and also that energy disperses with distance - in addition to sound having size - thus requiring large boundaries to be reflected specularly as the boundary dimension must be as large or larger than the dimension of the wavelength of the reflected wave.

[MyPutzyRod]

Thanks for the response SAC.

First, the boundary: A 4'x2' OC Panel 4 inches covered in wood laminate. Big enough?

Second: Angle of incidence equals angle of reflection, therefore, alter the angle of incidence to whatever degree produces a reflection that avoids the listening position, aka angle this reflective boundary by a factor of the difference between the original angle and the intended, correct?

Third: what is more critical: the maintenance of energy or the lengthening of the ISD? My reasoning for multiple redirection is to add some time to bump the ISD from just ~14ms to ~18ms. The downside being energy loss.

I find all of your posts to be fascinating, and I hope I don't frustrate you with my amateurism. Thanks again SAC!

[SAC]

Here the dilemma that must be addressed.

If the natural angle of incidence and angle of reflection direct the energy into the ISD, you must have some manner of changing these angles so that the energy is redirected.

Simply placing a reflector there directs the energy into the ISD!

So you must alter said reflective surface so that the angle of incidence = the angle of reflectance is such that the energy is redirected to another location.

Thus, if you start at the source, and then note the target , you need to find the incident spots and adjust the incidence = reflective angles to hit the new target.

The likelihood is that these spots already exist naturally, but in a different location than the incidence points that direct the energy in to the ISD. Thus you must alter the angle of incidence/reflection of the spots redirecting the energy in to the ISD to another angle such that the energy is redirected to the desired target. ...Lots of words to say something that I am sure is pretty obvious.

There fore you are essentially changing the angle of the wall in that region. And therefore in order to effectively do this for the incident specular energy, the boundary being changes must be as large as possible (noting that if the 'reflecting surface is smaller than the wavelength of the frequency, that the sound will diffract around the boundary and not be reflected and it will continue in the same manner and renter the ISD).

Therefore, you can do what is done in the RFZ concept - namely 're-angle'/reorient the reflective wall surfaces (which a panel would now function as - except that it would not need to be load bearing) such that the energy incident in that region is redirected to where you want it to go - and then it can be diffused or absorbed as is consistent with your acoustical model. This is most commonly done with a false non-load bearing partition or wall in order to maximize the surface area and effectiveness relative to all of the incident energy.

Does this make sense?

[MyPutzyRod]

Great read SAC. I have a much clearer picture of what and why, and was thinking of using a laser pointer and mirrors for the "how". Thoughts on this method of finding the initial angle and then altering it to shoot the energy to an exact location, where it will be directed once more toward diffusion?