Concert Hall sound

[Fitzcaraldo215]

9 hours ago, Blackmorec said:

I’m really having some difficulty agreeing with a lot of the posts in this thread. 

 

The purpose of a sound system and listening room is to reproduce what’s on the recording and really nothing more. If a recording is made in a hall, the longer reverb times are part of the recording and have nothing to do with the listening room. In your room you should hear the original note coming from a specific origin, you should hear its decay, which has direction and you should hear the reflection (time delayed and opposite decay direction). What tells you the recording is in a large concert hall is the directionality of the decay and the timing of the reflection.  If you have a large, lively listening room with high rt  what you hear is both the recorded venue’s acoustic and your room’s acoustic. Very confusing. 

As for room boundaries, they should play no role in terms of sound stage size. The sound stage is created in your head, not your room and the brain uses reflection time, direction of decay, phase and relative amplitude to ‘visualise’ the venue. In nature sounds behave in a ‘natural’ way....and your brain uses all the information related to the sound to characterise what made it, where it came from, how far away it is and whether it was made in a room, hall or open space. To sound ‘real’ a sound recorded in an enclosed space needs to have the correct spectral balance,  a clear pinpoint source, an acoustic delay, a reflection and the correct amplitudal relationships between original sound and reflection. The timing of the reflection and its amplitude need to ‘agree’ with what happens in nature.

Take a large hall with high RT.  The recording should have a pinpoint start (all sounds in nature emanates from a single location), should decay in the direction of the reflection, should have a high amplitude reflection which should have a more diffuse character and should decay in the opposite direction. When all those characteristics of the sound have the right relationship to one another, your brain will assign size, and relative reflectivity of the recording venue and assign a degree of ‘realness’ according to how all the attributes of the music match what would occur naturally if you were actually seated in the venue with the musicians. 

As for high rt recordings sounding muddled, this should not be the case if its a well made recording and if your system is resolving and reproducing all its detail. If it does sound muddled that’s a very good indication that your brain is missing some sonic clues, meaning that your system is failing to fully resolve all the recording’s information or your listening room is distorting the information with too many high amplitude reflections reaching your ears

Very well said.  However, I disagree that room boundaries have no effect on the image we hear.  It is well known in acoustic theory and indisputable that room modal variations in the bass and their normally very large, narrow band frequency peaks and dips are a function of reflections based on room dimensions, construction and materials.  Also, for example, at higher frequencies apparent soundstage width is affected by side wall reflections via speaker placement and toe in/out, depending on speaker directivity.

 

Yes, absolutely, we want the sound of the recording, including spatial and acoustic cues from the hall, to override the sonic signature of the listening room, both in stereo and Mch.  That does not require an ugly and unpleasant sounding anechoic listening room.  It merely requires a room in which the effects of the listening room are controlled to be sufficiently neutral, well behaved and down in level relative to direct sounds from the speakers.  And, no it does not require excessive absorption or passive treatments.

 

As far as Concert Hall Realism goes, nothing is perfect.  But, there are decidedly different degrees of plausibility of the image conveyed to home listeners between conventional stereo and Mch.  As has been restated numerous times, discretely recorded Mch achieves this best by far as a result of capturing more information on more channels about the size and acoustic of the hall and by preserving much of this in playback to the 360 degree hearing our ears are naturally capable of.

 

I dare say that those who argue that stereo is just as or nearly as good have not made a comparison using a properly set up Mch system or they lack familiarity with sound live in the concert hall.  I find the difference plain as day, repeatedly on numerous Mch systems.  And, there are very large numbers of extremely well engineered hirez Mch recordings that easily illustrate this.

 

 

 

 

[fas42]

6 hours ago, Fitzcaraldo215 said:

Yes, absolutely, we want the sound of the recording, including spatial and acoustic cues from the hall, to override the sonic signature of the listening room, both in stereo and Mch.  That does not require an ugly and unpleasant sounding anechoic listening room.  It merely requires a room in which the effects of the listening room are controlled to be sufficiently neutral, well behaved and down in level relative to direct sounds from the speakers.  And, no it does not require excessive absorption or passive treatments.

 

 

A good a recording as any to demonstrate this is the original mastering of Led Zeppelin I. This opens up massive vistas, yawning caverns of sound - stretching "as far as the ear can see". Yes, "artificial", contrived - but highly impressive as a showoff piece as to what stereo playback can conjure up when it's working well.

[STC]

 

I am retyping for the third time and I couldn't enter the text after the quote! ?

 

There are many references to ILD and ITD which are crucial to understanding hearing and also stereo reproduction. 

 

I have previously written about how can stereo or rather cannot reproduce sound behind the microphone accurately unless with the aid of phase manipulation like using QSound DSP. Reverberation Comes from every direction. In a concert hall, you have no choice but to hear all of them despite some may not be that useful. Reflection from the ceiling is essential monotonous to our ears. It is not necessarily useful in a small room.

 

Quote

Reverberation is result of ray bouncing. These rays are sum (by phase and aplitude, complex numbers in math) in point. If the sum in point are captured right (by phase and aplitude), reverberation will captured correctly anyway.

 

Yes, only to those waves coming from the front. It also captures some wave from the back but that will distort and muddy the sound when reproduced through the front speakers. No magic there. Take your smartphone and record someone to talking behind you. Play the sound in your system. Do you hear them coming from front or back? The same applies to hall/venue reverberation.  It is not intentionally captured. It will be missing from the recordings to avoid distorting the sound of the front speakers when replayed.

 

 

Quote

Room correction by EQ destroy the sum. And for sound field reconstruction in listening room, room EQ correction is not need as separate process.

4

 

I do not use EQ and I never mentioned it. 

 

 

9 hours ago, audiventory said:

 

I'm only want to say that it's necessary to focus on base of process, reduce subjects of considering.

 

Reverberation is result of ray bouncing. These rays are sum (by phase and aplitude, complex numbers in math) in point. If the sum in point are captured right (by phase and aplitude), reverberation will captured correctly anyway.

 

 

Listening room acoustic model is used instead. Record is transformed via this model to adapt the record to playback in given room. It is like to representation one sound object in different coordinate systems (it's not physical correct example, just for explanation). It is direct way to achieve accurate sound. Room EQ correction will solved as inside the transformation.

How to do it, I don't know on current technical level.

 

 

What is ILD and ITD?

21

[STC]

9 hours ago, Fitzcaraldo215 said:

I dare say that those who argue that stereo is just as or nearly as good have not made a comparison using a properly set up Mch system

 

That's the biggest problem here. As far as know, no one here actually has a multichannel system for high-end music.  A couple of decades ago, an acquaintance showed his high-end system which sounded pretty good.  On the way out, he wanted to show his high-end HT system and played Roy Orbison concert DVD. I actually like the HT sound but only to be laughed by other senior audiophiles.  

[Ralf11]

doesn't Kal have a "multichannel system for high-end music" ??

[esldude]

35 minutes ago, Ralf11 said:

doesn't Kal have a "multichannel system for high-end music" ??

 au contraire

 

Kal has "a high end music system for multi-channel music."

 

??

 

 

[audiventory]

4 hours ago, STC said:

I have previously written about how can stereo or rather cannot reproduce sound behind the microphone accurately unless with the aid of phase manipulation like using QSound DSP.

 

Non-phase-correct record cannot be corrected. Because each recorded object (instrument, voice, listener cough, chair crunch, conditioner hum, etc.) should be separated exactly and phase "picture" must be reconstructed for each one via concert hall acoustical model.

 

But, if even the object will extracted separatelly, it will altered, comparing the object in scene. Because extracted stuff is sum of rays in the concert hall.

 

Example: When we drink orange juice, we can't feel orange fruit texstures of original fruit. To do it, we must extract orange fruit from the juice. If we extract fruit parts, we can't assemble it to original fruit.

 

 

 

4 hours ago, STC said:

Play the sound in your system. Do you hear them coming from front or back?

 

It is not matter where sound object is detected by our perception.

Acoustics rays come from all directions (360 degrees horizontally and vertically) always in any room.

 

When brain hear more intensive rays from front, it decide, that object at front.

If the brain hear bounced rays with delay from rear, it deside that wall there.

If the delay is long, the brain think that wall far and room is big. We hear it as reverberation, echo, chorus.

 

In mixing and postproduction reverberation and chorus may be used to room size emulation. But it can't restore original room as is (see above juice example).

 

 

4 hours ago, STC said:

Yes, only to those waves coming from the front.

 

Wave spread trajectory (coming waves ) is ray. There are infinite ray number.

 

Reverberation is neither ray nor sound nor wave.

 

Reverberation is audible effect, that rise inside our brain due time delays between mixed rays (front, rear, side, top, bottom).

 

We can't capture effect (reverberation).

The reverberation do not exists in reality.

It is our brain interpretation of the rays' interference in a listening point.

 

If we capture the interference of the rays, then reverberation effect will kept into captured stuff.

 

Example:

Rays may be considered as virtual infinite small pipes to transmit sound from instrument to ear.

These pipes have different length.

Because sound come from instrument to ear thru the pipes with different delay. The delay depend on the pipe length.

The delay is called as "reverberation".

 

 

 

[fas42]

The following could be of interest - it's a recording I took of the current NAD rig to test the recently acquired USB microphone -  a cheapy from Aldi. The microphone was a metre or two behind the Sharp boombox speakers, and the speakers were directly facing an end wall, several metres away - plasterboard, with typical window. So the sound has zero direct content, apart from the bass reflex port at the back - everything one hears is energy bouncing off the end wall, and some from ceiling, and side walls. Note, the rig is just OK quality in this, it has never reached the standard I aim for.

 

 

 

[STC]

1 hour ago, audiventory said:

Non-phase-correct record cannot be corrected. Because each recorded object (instrument, voice, listener cough, chair crunch, conditioner hum, etc.) should be separated exactly and phase "picture" must be reconstructed for each one via concert hall acoustical model.

 

But, if even the object will extracted separatelly, it will altered, comparing the object in scene. Because extracted stuff is sum of rays in the concert hall.

 

Example: When we drink orange juice, we can't feel orange fruit texstures of original fruit. To do it, we must extract orange fruit from the juice. If we extract fruit parts, we can't assemble it to original fruit.

 

I have no idea what you referring to.  Have you listened to Amused to Death?  Looks like we are on a different wavelenght because most of what you have written is contrary to what I have read and implemented. Do you have a proper citation of the points you are trying to make here? 

 

Quote

 

Reverberation is neither ray nor sound nor wave.

 

Reverberation is audible effect, that rise inside our brain due time delays between mixed rays (front, rear, side, top, bottom).

 

 

I just don't know how to reply to this one.

[STC]

17 minutes ago, fas42 said:

The following could be of interest - it's a recording I took of the current NAD rig to test the recently acquired USB microphone -  a cheapy from Aldi. The microphone was a metre or two behind the Sharp boombox speakers, and the speakers were directly facing an end wall, several metres away - plasterboard, with typical window. So the sound has zero direct content, apart from the bass reflex port at the back - everything one hears is energy bouncing off the end wall, and some from ceiling, and side walls. Note, the rig is just OK quality in this, it has never reached the standard I aim for.

 

 

 

3

 

Quote

The microphone was a metre or two behind the Sharp boombox speakers, and the speakers were directly facing an end wall, several metres away - plasterboard, with typical window. So the sound has zero direct content, apart from the bass reflex port at the back - everything one hears is energy bouncing off the end wall, and some from ceiling , and side walls

.

 

Fas24, is this what you have been telling us all this while? Listen to speakers from behind? 

 

BTW, I can hear direct sound in the recording and you are wrong to claim there is no direct sound just because you are listening to the speakers from the back of the speakers. It still radiates sound to the back although much attenuated.

[fas42]

36 minutes ago, STC said:

 

.

 

Fas24, is this what you have been telling us all this while? Listen to speakers from behind? 

 

BTW, I can hear direct sound in the recording and you are wrong to claim there is no direct sound just because you are listening to the speakers from the back of the speakers. It still radiates sound to the back although much attenuated.

 

Ummm, no ... just that one can listen from a spot away from the nominal right area, where virtually all the sound heard is reflections from surfaces. There is direct sound in the clip from the bass port facing to the rear, from the back of the midwoofer, but the tweeter is completely external to the cabinet, on the front.

[STC]

I mentioned somewhere in this thread about concert halls using external speakers to increase their natural reverberation. You can find some info here.

 

 

Quote

 

The Meyer Sound D-Mitri® digital audio platform powers the Constellation acoustic system. Ambient acoustical energy is picked up by 76 microphones, and returned to the room as early reflections and late reverberations through 223 discreet, self-powered loudspeakers and 12 compact subwoofers.

 

 

 

As you can see from the above paragraph even the real live performance can be enhanced by modifying the reverberation by using surround ambiance speakers. This is what I am doing based on what the ambiphonics.org is doing for so many years.

 

Watch the video in the concert hall how a clap sound can be altered by the ambiance reverb speakers using the Constellation system.  Watch from 1:00.

 

 

 

@audiventory , as you can see here the so-called reverberation that can be constructed in the brain as you suggested requires external aid from many directions with aid of many speakers. 

 

 

Search for more info about the Constellation system and Logomo hall which can be transformed into any kind of hall to match the desired reverberation time of the music. All the argument about it is possible to recreate the space with two channels recordings is lacking the depth in understanding the subject of reverberation and recording techniques.

 

“The ideal concert hall is obviously that into which you make a not very pleasant sound and the audience receives something that is quite beautiful.” - Sir Adrian Boult 

[semente]

2 minutes ago, STC said:

 

 

@audiventory , as you can see here the so-called reverberation that can be constructed in the brain as you suggested requires external aid from many directions with aid of many speaker

 

It will also have to be recorded with as many mics as the many speakers, and these should form a spherical cage.

 

We've been there. ?

 

This is in Southampton, maybe @mansr could check it out?

 

 

Virtual Acoustics and Audio Engineering

Our research on audio aims to further scientific knowledge and to develop new technologies related to the capturing, synthesis and control of sound fields. We do that by combining our expertise in acoustics, signal processing and psychoacoustics.

https://www.southampton.ac.uk/engineering/research/themes/acoustics/virtual_acoustics_and_audio_engineering.page

[STC]

2 minutes ago, semente said:

 

It will also have to be recorded with as many mics as the many speakers, and these should form a spherical cage.

 

We've been there. ?

 

This is in Southampton, maybe @mansr could check it out?

 

 

Virtual Acoustics and Audio Engineering

Our research on audio aims to further scientific knowledge and to develop new technologies related to the capturing, synthesis and control of sound fields. We do that by combining our expertise in acoustics, signal processing and psychoacoustics.

https://www.southampton.ac.uk/engineering/research/themes/acoustics/virtual_acoustics_and_audio_engineering.page

 

It amazes me that until now you have no idea what's that used for.  Maybe, southampton.ac.uk is a new discovery for you but I have been referring to that for so many years. You are wrong. You have no idea of the purpose and use of that. 

[STC]

5 minutes ago, semente said:

It will also have to be recorded with as many mics as the many speakers, and these should form a spherical cage.

 

This is enhancing the performance itself. Be it live performance or experimental speakers on the stage. The reverbs comes separately. The funny thing about you repeatedly likes to talk about the spheres or balls that until now it didn't occur to you why there isn't an audio sample to support your assertion. How many channels do you think you need?  Even somehow, you managed to convince a 120 member into 120 cages and record the sound on a specially built mega size hall, you still need to add the reverbs otherwise the space cues will be missing from them as they were closed miked. That's rather basic.

[semente]

1 hour ago, STC said:

 

This is enhancing the performance itself. Be it live performance or experimental speakers on the stage. The reverbs comes separately. The funny thing about you repeatedly likes to talk about the spheres or balls that until now it didn't occur to you why there isn't an audio sample to support your assertion. How many channels do you think you need?  Even somehow, you managed to convince a 120 member into 120 cages and record the sound on a specially built mega size hall, you still need to add the reverbs otherwise the space cues will be missing from them as they were closed miked. That's rather basic.

 

This is how I see it. A pair of mics used to record say a guitar in a small chapel capture direct sound and reflected sound. This recording reproduced by a pair pf single driver speakers in free-field will not recreate the original soundfield because both direct and reflected sound will be coming from the same point source. If you use a spherical mic array (sphere with mics) the mics will capture direct and reflected sound reaching it from all directions. Then place the listener inside a spherical speaker array cage in an anechoic chamber and reproduce the multi-channel repcording one chaner into a corresponding speaker.

 

A 360º photography smartphone app can be used as an analogy:

 

http://www.3dvirtualsolutions.com/our-services/360-photography/ (have a look at the samples)

 

Imagine a spherical camera array taking photos inside a church. If you create a spherical computer-display array cage you can reproduce a 360º landscape, with a spherical speaker array cage you can reproduce a 360º soundscape.

[STC]

28 minutes ago, semente said:

This is how I see it. A pair of mics used to record say a guitar in a small chapel capture direct sound and reflected sound. .....

 

This itself shows you do not know what will be captured by the microphone at a given location. Do you mind to give the definition of reverberation before we can continue. Your insistence of talking about something which you  do not understand is hard to have a rational discussion because you do not have a working example. 

 

So let’s start with the quote above. Explain that sentences. 

 

[semente]

1 hour ago, STC said:

 

This itself shows you do not know what will be captured by the microphone at a given location. Do you mind to give the definition of reverberation before we can continue. Your insistence of talking about something which you  do not understand is hard to have a rational discussion because you do not have a working example. 

 

So let’s start with the quote above. Explain that sentences. 

 

 

Reverberation is reflected sound. The reflection produced by a distant wall in a large room will take longer to reach the listener or microphone. It will also be lower in level in comparison with the direct sound or a reflection produced by a wall closer to both listener and source.

A mic in a room will capture both direct and reflected sound. This, the delay and amplitude difference between direct and reflected sound, is perceived as spatial information. The amount of absorption of the walls will affect the quality of the reverberation. By comparing what you are listening to past (live) experience you will know whether the recording was performed in a drier or in a more reverberant space. Music halls use a mix of absorptive and reflective surfaces in order to distribute "early" sound more evenly though as distance to sources increases so does the attenuation in the high frequencies and there's a change in balance between "early" and "reflected" sound.

 

It looks to me as though you are trying to correlate reverberation time of the venue with that of the llistening room. I may be wrong but think that you are confusing things.

The (sound of the) "original" reverb of the venue should be in the recording (unless close-mic'ing was used). The reverb time in the listening room, and its relative amplitude will only have a negative effect on the quality of the reproduction of the "original" reverb. You'll be adding a layer of confusion to the sound.

I understand where you are coming from but I think there's no way you can achieve what you are looking for without two rear speakers and a 4-channel recording.

 

My old room was 3.3m wide, 3.3m high and 8.40m with thick masonry walls and concrete floor and celing slabs. The reflection of the wall behind the listener (5.5m away) was quite damaging to the sound so sometimes I'd place a foam mattress vertically about 1m behind the listening spot.

The room acoustics were definitely not nice for reproduction or for talking, and whenever we had more than two guests I'd tire really quickly...

But it sounded glorious when my son played the piano or sang.

[semente]

The neighbour living on the top floor has pulled down a few walls, making the living room 4.8m wide and 11.2m long. He has a pair of grand pianos and every once in a while he hosts musical soirées where his great friend Artur Pizarro will often come to play.

[semente]

 

[STC]

38 minutes ago, semente said:

 

Reverberation is reflected sound. The reflection produced by a distant wall in a large room will take longer to reach the listener or microphone. It will also be lower in level in comparison with the direct sound or a reflection produced by a wall closer to both listener and source.

A mic in a room will capture both direct and reflected sound. This, the delay and amplitude difference between direct and reflected sound, is perceived as spatial information. The amount of absorption of the walls will affect the quality of the reverberation. By comparing what you are listening to past (live) experience you will know whether the recording was performed in a drier or in a more reverberant space. Music halls use a mix of absorptive and reflective surfaces in order to distribute "early" sound more evenly though as distance to sources increases so does the attenuation in the high frequencies and there's a change in balance between "early" and "reflected" sound.

 

It looks to me as though you are trying to correlate reverberation time of the venue with that of the llistening room. I may be wrong but think that you are confusing things.

The (sound of the) "original" reverb of the venue should be in the recording (unless close-mic'ing was used). The reverb time in the listening room, and its relative amplitude will only have a negative effect on the quality of the reproduction of the "original" reverb. You'll be adding a layer of confusion to the sound.

I understand where you are coming from but I think there's no way you can achieve what you are looking for without two rear speakers and a 4-channel recording.

 

My old room was 3.3m wide, 3.3m high and 8.40m with thick masonry walls and concrete floor and celing slabs. The reflection of the wall behind the listener (5.5m away) was quite damaging to the sound so sometimes I'd place a foam mattress vertically about 1m behind the listening spot.

The room acoustics were definitely not nice for reproduction or for talking, and whenever we had more than two guests I'd tire really quickly...

But it sounded glorious when my son played the piano or sang.

 

Your reverberation definition would be better if you also include the time difference between direct sound, early reflection and late reflection. Also try again explaining the direction of the reverberation.  Just make it short. And please answer about the question I asked about those in quotes. 

[STC]

28 minutes ago, semente said:

 

 

And what am I suppose to make of the video. Speakers can record sound ? That’s what you told when you first started to show the spheres. Btw, why sphere and not a cube?

[STC]

48 minutes ago, semente said:

but I think there's no way you can achieve what you are looking for without two rear speakers and a 4-channel recording.

 

You got it right there! I use more than 4 channels. To be exact , 72 channels. 

[semente]

4 minutes ago, STC said:

 

And what am I suppose to make of the video. Speakers can record sound ? That’s what you told when you first started to show the spheres. Btw, why sphere and not a cube?

 

Watch the film again, and again, and again. You may end up with finding the answers.

[semente]

7 minutes ago, STC said:

 

You got it right there! I use more than 4 channels. To be exact , 72 channels. 

 

Now place those channels in a sphere around the listening spot.

 

Then all you need is a 72-channel recording from a spherical mic array. Contact the Institute of Sound and Vibration Research in Southampton, maybe they'll supply one.