Listening in an Anechoic Chamber - a report

[Cote Dazur]

As you said. It depends on the source.

The same source inside plenty of depth, outside no depth. So not so sure, but thank you for the reply.

 

[sarumbear]

The same source inside plenty of depth, outside no depth. So not so sure, but thank you for the reply.

Maybe it depends on the person.

 

[Cote Dazur]

Maybe it depends on the person.

Thank you, very enlighting.

 

[sarumbear]

Thank you, very enlighting.

I was joking

 

[Axo1989]

The same source inside plenty of depth, outside no depth. So not so sure, but thank you for the reply.

Interesting experimental potential, regarding how much front and side walls contribute (versus the recording). When @sarumbear says 'source' I assume both equipment and recording.

I know 'person' was a joke, but it wouldn't surprise me if different people perceived stereo image/soundstage differently. Analogous the the way some people get those old magic eye images and some don't.

 

[Axo1989]

It’s nice to see people who seems to know acoustics joining the conversation.

Haha thank you. I did study it for a bit, was going to be an architect, but changed course.

 

[Cote Dazur]

but it wouldn't surprise me if different people perceived stereo image/soundstage differently

I have no doubt that different people will perceive the stereo sound stage from the same system in the same seat differently. As it is created by our ears and our brain, so hugely personal.
My surprise this afternoon, was that on familiar recording, on a system setup outside, with speakers free of any surrounding, I am getting no depth.
I have more than one system in my home, any that is set up with equilateral triangle for speaker distance, with speakers well positioned, away from front wall and side wall, does reproduce depth, some more than other, but still.
I was expecting outside to have at least a some, but nothing is weird. Specially when left to right is very nice, well define. Just flat.
Hence my question to someone who stated he spent time in an anechoic chamber. To me outside and anechoic have similarities in the total absence of reflections.

 

[Newman]

Not how those metrics work. RT30 is measured over the smaller decay delta, then multiplied. For a linear decay, the value is the same as RT60.

I assume you mean calculated RT60 is "the same" as measured RT60. The way you wrote it could be misinterpreted as RT30=RT60.

In other words, RT30 is the method/protocol, RT is the metric.

Sure. Except in this case RT30 is an estimate being back-calculated from room impulse response. So also a metric, not a measurement of time.

The purpose of RT30 is to give an equivalent result in a noisier environment, where RT60 doesn't work accurately.

Sure. But the paper we were discussing discusses RT30 exclusively, and uses "reverberation time" and "RT" to mean RT30.

And after all that, did it make any difference to my main points, link? Especially that RT is not suited to making a characteristic assessment of domestic listening spaces in any case, hence much of the debate being moot?

cheers

 

[Mart68]

I have no doubt that different people will perceive the stereo sound stage from the same system in the same seat differently. As it is created by our ears and our brain, so hugely personal.
My surprise this afternoon, was that on familiar recording, on a system setup outside, with speakers free of any surrounding, I am getting no depth.
I have more than one system in my home, any that is set up with equilateral triangle for speaker distance, with speakers well positioned, away from front wall and side wall, does reproduce depth, some more than other, but still.
I was expecting outside to have at least a some, but nothing is weird. Specially when left to right is very nice, well define. Just flat.
Hence my question to someone who stated he spent time in an anechoic chamber. To me outside and anechoic have similarities in the total absence of reflections.

you'll still have reflections from the ground when outside, unless you hang the speakers from a crane or something (which is what Tannoy used to do when testing outdoors).

 

[LTig]

The same source inside plenty of depth, outside no depth. So not so sure, but thank you for the reply.

It depends how the recording (source) has been produced.

• The majority of recordings contains no depth information due to using multiple microphones whose channels are summed up in the mixing console using pan pots to position them somewhere between Far Left and Far Right. Those recordings sound flat if there are no reflections from walls in a room. If you play them in a room this rooms characteristic create an artificial depth and width (envelopement) but can also harm precision of imaging.
• Recordings using 2 or 3 microphones may contain depth information of the room where the music is produced if they are positioned accordingly. Playing them in a dry room (few reflections) or outside should recreate the acoustics of the production room.
• Some special treated 3D-recordings (Q-Sound coming to mind) use DSP to create artificial depth. Playing them in a dry room (few reflections) or outside should recreate this depth.

IME there are two different preferences among audiophiles - people who prefer a wide and enveloping soundstage, and those who prefer a pin point exact imaging. It's almost impossible to get both at the same time - Q-Sound being an exception.

You should play one of those Q-Sound recordings listed here to find out whether they produce some depth outside.

 

[dasdoing]

The majority of recordings contains no depth information

the reverb does. it seams to me that some people's ears don't translate the reverb to space. if you don't hear space in an stereo triangle outside this is obviously the case. on the other hand reverbs used to be very, very bad in the past, which could have contribuited to some not being able to hear it as space. But I think the main thing those people are missing is the visual clues of that virtual space.

 

[Axo1989]

I assume you mean calculated RT60 is "the same" as measured RT60. The way you wrote it could be misinterpreted as RT30=RT60.

The very short answer is no, the latter isn't a misinterpretation. If Kaplanis et al referred to T30 (or RT30 if that's how they styled it) of 0.4 seconds, that equals reverberation time (being the time it takes for reflections of direct sound to decay 60 dB).You don't double "RT30" to get "RT60". That will clarify your earlier discussion with @youngho.

I can do the long answer (it is pretty fascinating) but only if you are interested.

 

[Newman]

No thanks, all good. Simple terminology error by me.

 

[youngho]

The very short answer is no, the latter isn't a misinterpretation. If Kaplanis et al referred to T30 (or RT30 if that's how they styled it) of 0.4 seconds, that equals reverberation time (being the time it takes for reflections of direct sound to decay 60 dB).You don't double "RT30" to get "RT60". That will clarify your earlier discussion with @youngho.

I can do the long answer (it is pretty fascinating) but only if you are interested.

I would be interested in learning from the long answer. @Axo1989

 

[Newman]

I thought the long answer would warrant a new thread, hence my previous reply.

PS my terminology error was because I thought logically, that if T60 is the time taken to decay 60 dB, then T30 would be the time taken to decay 30 dB. But it isn't. T30 is also the time taken to decay 60 dB, but you only measure 30 dB decay time, then either double it based on a linear decay assumption, or use another multiplication factor based on some proper knowledge of the actual decay curve in the room in question.

I could think of at least two better labels than T30 for that particular measurement, but the industry went that way.

 

[ahofer]

Interesting Times article today about spending time in an anechoic room:


https://www.nytimes.com/2022/11/23/...ytcore-ios-share&referringSource=articleShare

 

[sarumbear]

Interesting Times article today about spending time in an anechoic room:


https://www.nytimes.com/2022/11/23/...ytcore-ios-share&referringSource=articleShare

The feeling he explains is similar to what I experienced but I only stayed inside the chamber (at Imperial College, London) for a few minutes.