Acoustic properties of glass

[Andysu]

Our niche predominantly focuses now on Point Source Coaxial Limited Channel Count (<9.x.6) Atmos, Videowalls, and Windows. We've gathered predictive and measurement data indicating that, generally, some bass frequencies pass through the windows. In a room equipped with 39 loudspeakers and 7 subs, the RPG ModViewser transparent diffusers have been installed to cover the glass. Additionally, there are on the market perforated sound-absorbing glass transparent panels. To mitigate unwanted reflections caused by the large videowall and extensive glass surfaces, it's advisable to position rear speakers sideways rather than directly facing the videowall.View attachment 367740View attachment 367741View attachment 367742
curiously the frequencies below 70-80 may not be permeating through the glass.
View attachment 367743

is there an actual video of the room how it sounds

 

[CINERAMAX]

is there an actual video of the room how it sounds

A Measurments no, The Owner made a video of the Custom Loudspeaker and aes 67 Amplifier Manufacturer Quested, it explains each channel.

 

[Andysu]

well , this whole glass thing makes me want to put on , theatrical AC-3 laserdisc THX and wow when that scenes fires up bass waves are impact dynamic i may pour a small baileys into class with ice cubes that look like glass , on a real professional JBL THX , AC-3

 

[egellings]

Glass absorbs part of the lows and strongly reflects mids and highs. Brick wall strongly reflects everything.

I'll bet that if the glass were as thick as a brick, it would reflect everything just as well as a brick does. To compare materials like that for acoustic properties, you would need test pieces that all have the same physical dimensions and are tested in an identical way. As it is now, you're testing the test and not the DUT (Device Under Test). Spoiler: Test engineer here.

 

[CINERAMAX]

Also the mounting frame architecture affects the responses.

 

[Vladimir Filevski]

I'll bet that if the glass were as thick as a brick, it would reflect everything just as well as a brick does. To compare materials like that for acoustic properties, you would need test pieces that all have the same physical dimensions and are tested in an identical way. As it is now, you're testing the test and not the DUT (Device Under Test). Spoiler: Test engineer here.-

Of course glass thick as a brick will reflect everything. But glass so thick is very seldom used in windows, usually thickness is 3-6 mm for domestic/residential windows/doors and 8-12 mm for big shop-windows and big domestic glass walls. Thankfully, there are many tables with already measured acoustical properties (absorption coefficients, etc.) for many materials with different thickness.
Spoiler: Acoustics/Loudspeaker engineer here.

 

[Vladimir Filevski]

Our niche predominantly focuses...

Impressive!
What is the thickness of the clear acrylic/polycarbonate material for the RPG diffusors?

 

[Miguelón]

Sorry, but again I need to say "no" for you.

If you look and learn very carefully on my Fig-12 and Fig-13 in my that post, you can understand that my tweeters and super-tweeters are singing together "audibly" in Fq zone of around 5 kHz to 20 kHz.

I see, is on the crossover region, so many figures I was a bit loss… Happy to see the bowl helping on audible region apart from eating vegetables

 

[Miguelón]

Of course glass thick as a brick will reflect everything. But glass so thick is very seldom used in windows, usually thickness is 3-6 mm for domestic/residential windows/doors and 8-12 mm for big shop-windows and big domestic glass walls. Thankfully, there are many tables with already measured acoustical properties (absorption coefficients, etc.) for many materials with different thickness.
Spoiler: Acoustics/Loudspeaker engineer here.

Not very thick, a double glass I think about 8 mm…
As you mentioned is not very significant as is behind the speakers so highs and mids don’t be reflected so much.
Probably more influence of a marble table just beside the left speaker is reflecting more highs and mids than the glass

 

[SIY]

Of course glass thick as a brick will reflect everything. But glass so thick is very seldom used in windows, usually thickness is 3-6 mm for domestic/residential windows/doors and 8-12 mm for big shop-windows and big domestic glass walls. Thankfully, there are many tables with already measured acoustical properties (absorption coefficients, etc.) for many materials with different thickness.
Spoiler: Acoustics/Loudspeaker engineer here.

It depends on the sort of glass and if it's had surface ion exchange a la Gorilla Glass.

Spoiler: glass science geek

 

[Andysu]

I'll bet that if the glass were as thick as a brick, it would reflect everything just as well as a brick does. To compare materials like that for acoustic properties, you would need test pieces that all have the same physical dimensions and are tested in an identical way. As it is now, you're testing the test and not the DUT (Device Under Test). Spoiler: Test engineer here.

glass inches thick it would be silly expensive than actual bricks

 

[egellings]

glass inches thick it would be silly expensive than actual bricks

Of course it would; I don't recommend using it for that.

 

[dualazmak]

I see, is on the crossover region, so many figures I was a bit loss… Happy to see the bowl helping on audible region apart from eating vegetables

My another thread would be also of your reference and interest, I hope;
An Attempt Sharing Reference Quality Music Playlist: at least a portion and/or whole track being analyzed by 3D color spectrum of Adobe Audition

 

[CINERAMAX]

Impressive!
What is the thickness of the clear acrylic/polycarbonate material for the RPG diffusors?

3/8" aprox.

 

[Keith_W]

@dualazmak your glass salad bowl reflectors would not have the same frequency dependent absorption coefficients as a window pane. The reason your salad bowls are selectively reflective of high frequencies is because they are so small with respect to bass wavelengths. It will seem as insignificant to a bass wavelength as King Canute trying to stop the tide. Because of the bowl shape, glass is also much more rigid than if the same material was shaped as a pane.

Window panes have three frequency zones which impact sound. Short wavelengths which do not have much energy simply reflect back into the room with minimal attenuation. Longer wavelengths have more energy - as the compression/rarefaction wave with high/low pressure impacts the pane, the pane flexes in response and stores energy. The energy is then released in both directions - back into the room, and outside to the environment with a lot of energy lost as heat. The third zone is the resonant frequency, where it extends the decay time of the frequency in question and may cause other effects such as rattling on the jambs.

Thus window panes attenuate bass by acting as membrane absorbers, resonate at certain frequencies, and reflect high frequencies with less attenuation. The result is a treble tilt.

As you can imagine, your rigid glass bowl won't act this way because it is rigid. It is HF selective because it is small.

 

[BlackTalon]

glass inches thick it would be silly expensive than actual bricks

Of course it would; I don't recommend using it for that.

Glass block is a thing. Was used a lot for skylights in the 1930s/ 40s. It's been used in walls a lot over the years.

Here is one manufacturer: https://sevesglassblockinc.com/ STC 38 up to 59.

 

[Andysu]

windows glass reflection of conversation with laser microphone , so be careful what you say behind closed doors as there is always windows and that glass has ears listening in on it , maybe ?

 

[dualazmak]

As you can imagine, your rigid glass bowl won't act this way because it is rigid. It is HF selective because it is small.

Yes, this is exactly what I am testing/evaluating.
I use the random heavy-hard cut-glass surface only for wide-3D reflective dispersion of the HF sound given by the metal-horn super-tweeters FOSTEX T925A covering ca. 8 kHz - 20 kHz (together with my tweeters)!

You would please understand my objectives by reading carefully and thoroughly my Part-1 post #912 and my posts (Part-2, Part-3) thereafter!

 

[EJ3]

Not very thick, a double glass I think about 8 mm…
As you mentioned is not very significant as is behind the speakers so highs and mids don’t be reflected so much.
Probably more influence of a marble table just beside the left speaker is reflecting more highs and mids than the glass

I have seen places that had some glass walls that were made form hunks of glass the size of cinderblocks.
The particular one that I am thinking of was a restaurant named The Cavallaro in Charleston, SC that I frequented about 4 times a year with dates when I was a teenager in the 1970's.
That takes me off subject a bit:
It was a higher class but accessible place if you could become passable in a coat & tie (despite my longer than average [for their clientele] hair.
And the girls that I dated always new how to dress well & sultry without being indiscrete.
Ah, an epiphany: perhaps that is why I did not get married until I was 48.
At any rate, the entry doors where between these glass blocks.
And I have seen them in one other place but cannot recall where.
The place had pretty good acoustics inside, as there where a number of softer surfaces inside, even though there was usually some sort of somewhat subdued band (Jazz, 40's Swing & Shag music).
& in between sets someone played piano, usually.

 

[Miguelón]

windows glass reflection of conversation with laser microphone , so be careful what you say behind closed doors as there is always windows and that glass has ears listening in on it , maybe ?

They will be a little bored by my classical repertoire at the piano, and repeating scales, arpeggios and ultra-slow executions of difficult passages…

Conversely I have neighbors whose reproductive activity could appear on a National Geographic documentary or perhaps at the Guinness Book of World Records because of their spectacular SPL peaks.

But we don’t need a laser to appreciate them, specially at the final crescendo, the bricks that divides our apartments are not enough for isolate their low mids and low highs respectively.

I will publish a post asking for acoustic isolation perhaps, living on the town center has interesting sound issues.
My downstairs neighbor complaints about my piano, we complaint about the couple I mentioned, all of the building compliant about a student’s apartment (even the students complaints), and so forth…