Kris
20-06-2010, 13:59
Firstly, please excuse this rant (and the fact that I haven't posted for a while, even though I have been reading!). I can assure you it's not aimed at anyone in particular, it's more aimed at correcting the urban myth and misinformation which is widely circulated by the TNT Audio 'Support Real Stereo' campaign. http://www.tnt-audio.com/topics/realstereo_e.html
A few days ago I read a new post on the "Adventures in High Fidelity Audio" blog, http://www.adventuresinhifiaudio.com/15/06/2010/real-stereoturn-me-up-and-save-fm-three-very-worthwhile-causes/ and frankly, what was written saddened me greatly. Although well meaning, it only reinforces the misinformation, and hence prompted me to write this post.
True stereophonic sound, as devised by Blumlein
What does TNT-Audio actually mean by 'true Stereophonic sound'? I think their webpage is quite clear on the matter, two discrete channels each feeding one speaker.
I think we have to take this definition as read, especially considering that if you ask most people what 'stereo' means they'll reply something along the lines of “two channel sound”.
Within the bounds of this TNT-Audio definition then, Blumlein did not invent or devise Stereophonic sound. Sorry, but he DID NOT. And in writing this post, I'm trying to set the record straight.
Firstly let’s look at the definition. Stereophonic sound does NOT mean two chanel two speaker sound. What it means is:
Stereophonic sound, commonly called stereo, is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing.
Yes, stereophonic sound is the reproduction of sound using two OR MORE channels (and hence speakers). Stereophonic sound therefore is multichannel sound. And this is exactly what Blumlein created.
Actually, his patent doesn’t even mention stereo or stereophonic. The term was invented by Western Electric and popularised by Decca. The term 'stereo' cannot be attributed to Blumlein. And actually, apparently, not once in any of his writings or patents does he use the term. Blumleins patent is all about recording and reproducing binaural sound using a 'plurality' of speakers. I.E. more than one, and not necessarily two
If you don’t believe me, go read his patent yourselves. It’s available online at http://www.doramusic.com/patents/394325.htm
the invention consists in a method of transmitting, recording and/or reproducing sound wherein a plurality of transmission channels so interact, each upon each, or are in such relation or so relatively modified in combination and subsequently re-separated, that the complete intelligence initially transmitted is further conveyed, differently arranged, between the channels.
He goes further than that. In his patent he even described using multiple channels and multiple speakers to capture and reproduce HEIGHT.
The TNT-Audio 'Support Real Stereo' webpage champions Blumlein, which is great, but they appear not to have read, let alone understood his patent. Furthermore, throughout their blurb they completely misrepresent his views, his patent, and his far-sightedness:
With just two correctly designed and positioned microphones
the invention is not limited solely to the use of two microphones
Ironically, the consumer electronics industry, which was given such a gift in the invention of stereo, is now shifting its attention more towards home theatre and the multi-channel sound developed primarily for that medium.
It will be clear that the invention is particularly applicable to talking motion pictures and the following description will therefore be given with reference to this application.
TNT talk about irony when the actual real irony is totally lost on them. Yes, multichannel sound, as devised by Blumlein, was specifically intended for use in the film industry! He even had the idea whilst in the cinema watching a film with his wife!
True stereophonic sound, as devised by Blumlein, is quite capable of reproducing such an event with just two channels and two loudspeakers, so why complicate the issue with more channels and more speakers?
It really is unbelievable. They champion Blumlein then ask why use more than two channels and speakers! Here's what Blumlein says:
The above described system is based upon consideration in which no account is taken of sound reflections of interference either during recording or reproduction. If difficulties arise from this cause they may be overcome by employing a second pair of loud speakers differently spaced and having a different modifying network from the first pair: or a row of speakers may be used with a composite, progressive modifying network to supply them
(My bold).
Why complicate the issue with more than two speakers? Because Blumlein foresaw and made allowances for it. Throughout his patent he actively encourages the use of more than two speakers. Why? It's quite simple and straightforward - two speakers cannot accurately reproduce (using Blumleins phrase) "a complete directional sound picture".
You see, Blumleins vision was to record the sound field created in a given space, using a plurality of microphones and reproduce that sound field using a plurality of loudspeakers. Recreating using multiple microphones and loudspeakers, the sound field otherwise obtained and reproduced binaurally. And binaural is surround sound!
Notice I'm saying 'sound field', not 'sound'. Sound field (a modern term which means roughly the same as Blumleins 'sound picture') refers to the complete three dimensional sound produced in a given space - up, down and behind, as well as from the front. So, for example, when recording an orchestra, in order to capture the sound field, one doesn't actually mic up and record the orchestra, but record the sound produced in that room while the orchestra is playing. Which is actually what Blumlein was describing in his patent. he even experimented with placing his microphones in different places in the room, far away from the band or orchestra. He was trying to capture the entire sound created in the room. In his patent he even discusses capturing and reproducing the sound created from beyond the edges of the screen.
As you know, our ears pick up sound from all around us. And when we are listening to a live concert or whatever, we are hearing the sound that is produced in that room. Both the direct sound from the players, and the indirect sound that bounces off the walls and reverberates around the room.
Stand in the middle of a group of people - you will hear sound from all around you, behind, above, and below, as well as from in front of where you are standing. Which is why Alan Blumlein was interested in obtaining: "a complete directional sound picture".
So if indeed this is so, then why doesn't Blumlein specifically mention capturing sounds from the rear? Well, Blumleins patent was so futuristic and out of the box that few people of the time could understand what he was talking about in the first place. He even had to write a few papers trying to explain his invention in plainer English. Secondly, Blumlein was primarily concerned with the transmitting and storage of two channels, to record and reproduce sounds from multiple directions, using multiple mics and multiple speakers. And it was hard enough to do encode these two channels into one record groove, let alone more than two channels! And thirdly, he had to stop work on his audio inventions in order to concentrate on more pressing issues of the day. However, even if he didn't specifically mention it, his patent is chock-a-block full of clues that point to how he would have progressed his audio experiments had he been able to.
He was very aware of sounds from the rear - which binaural recording picks up just as well as sounds from the front. The microphone and mic technique he devised was a surround sound one - a crossed pair figure of 8 which picks up sound from 360 degrees, the rear sound being reproduced out of phase, which he was well aware of and even allowed for by saying that if the sound reflections interfere with the reproduction, one can use a second pair of loudspeakers differently spaced and with a different modifying network. Without realising it, Blumlein had invented surround sound! And actually, many people (including the BBC) recognise this patent of Blumleins as being a Surround Sound patent. This is especially true not just because of his surround sound mic, but also his mentioning of the capture, recording and reproduction (using additional channels & speakers) of height information.
Now I have to admit, in this patent he was primarily concerned with accurate sound location in relation to what was happening on the movie screen, and in this regard he does say that we will naturally discount any sound not coming directly from the visual sound source. But then again, the movie screen was in front of him, Imax hadn't been invented back then!
Unfortunately Blumlein didn't have a crossed pair figure of 8 mic to work with in his experiments. If he had I am in no doubt that one of his next steps would have been to investigate the out of phase sounds coming from the rear and to place the mic in the middle of the room and have his assistants walk around the mic in a circle, whilst reproducing that sound in the downstairs auditorium using four loudspeakers. I feel it's one of the main reasons he devised the cross figure of 8 mic technique. After all, he does go into detail about the phase differences captured by the mics, and that his technique was to capture the echoes produced in a room and to be reproduced with directional significance.
To my ear only Stereo does that, as it presents the music in a believable 3 dimensional space before you, the listener, with both image width left to right, image height and image depth.
Yes, two speaker stereo does present sound in a believable 3 dimensional space before you. But natural sound doesn't just come from the front. It comes from all around us. Respectfully, two speaker stereo can never accurately reproduce an entire sound field. That's not my opinion, it's a fact. Two speaker front positioned stereo cannot accurately spatially reproduce the sound of someone sitting behind you, or above you, or below you. The only way to accurately do this (apart from binaurally) is to have a plurality of speakers positioned not only in front of you, but behind, above, and below you, reproducing a signal which has (genuinely, not artificially) captured the entire sound field.
Of course, as soon as someone mentions surround sound, one automatically thinks of 'Dolby Surround' or whatever is the flavour of the month. 2.1 5.1 7.1 9.1 etc. Frankly I am no fan of these flavours of surround sound. These are discrete systems where the sounds are purposely recorded and pushed to certain speakers. The result is mostly a false and manufactured sound field.
That said, there is an accurate way of recording a sound field (including height) into two channels. And it's a system that used by football broadcasters around the world, the BBC and many others, even some computer game producers. It's called Ambisonics.
Nimbus record all their material in Ambisonics and as they say, Ambisonics "remains unchallenged as the most coherent and effective Surround Sound system". Which is why broadcasters around the world use it.
The problem is that domestic surround sound systems can't decode an ambisonic signal, so the broadcasters have to recode the ambisonic fomat into discrete Dolby surround sound, or whatever format is the flavour of the month.
Which is a great great shame. Ambisonics is not restricted to a certain number of loudspeakers. The signal can be decoded into 4, 6, 7, 8, 12, or even 200 speakers - including any number positioned above and below your listening seat.
The other big plus with Ambisonics is that there is no 'hot seat'. As it records and reproduces the sound field of the room in which the microphones are placed, you can walk around anywhere in your listening space and still be within the sound field, just as you can walk around anywhere inside a concert hall and still be within the sound field.
The other big bonus is that an Ambisonic recording is usually of much higher quality than other systems as it's more direct mic to recording - you don't need a big recording console and you don't need to artificially change the sound in any way. yes, Ambisonics can be, and generally is, of audiophile quality.
I've been using Ambisonics for many years. I've even got an ambisonic decoder in my car. Have had for decades. (That said, I don't have any speakers above or below me!)
And no, I don't just use it to decode Ambisonic signals. It's surprisingly capable of decoding virtually any surround sound signal. Including the Pink Floyd Holophonics. If you've not heard Pink Floyd or a Nimbus CD or record, or especially the Cowboy Junkies Trinity Sessions etc, through an Ambisonic (or other genuine non-discrete decoder) you've not heard it how it was intended to be heard. And it really is amazing. NO two-speaker system can reproduce it anywhere near accurately.
When reproducing non-surround sound material, yes, it's a bit hit and miss. Modern pop music or heavily multitracked music doesn't reproduce well, so I just switch it off. But simply recorded music, be it folk, jazz, choral, classical etc mostly sounds amazing. Far better, to my ears, than any two-channel system can reproduce it.
we declare that what we claim is: A sound and picture reproducing system . . . wherein the relative volumes of the reproducing loud speakers are so controlled as to provide apparent location of the sound original in coincidence with the optical location of the image from which the sound is supposed to emanate.
Now, can anyone who has actually READ his patent with an open mind really interpret this as meaning 'real stereophonic sound' as specifically described & promoted by 'Support Real Stereo' campaign?
The truth of the matter is that 'stereophonic' sound is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing. And as in natural hearing that includes sounds coming from behind, above and below us! Anything else is unnatural.
I have absolutely nothing against anyone who supports high quality two speaker stereo sound reproduction. And yes, I fully, completely agree that these modern all in one 'surround sound' systems are a total waste of space and money and do nothing to further the cause for good quality sound. However, that said, I hope I have shown that the information presented on the 'Real Stereo' webpage http://www.tnt-audio.com/topics/realstereo_e.html regarding his invention is inaccurate and, frankly, in my opinion, a disgrace to the memory of Alan Blumlein, a genius who didn't invent or devise solely two speaker sound reproduction but specifically decreed & intended his patent to be a starting point in multi-speaker sound recording & reproduction chain, foreseeing a future where people would use a plurality of microphones and a plurality of loudspeakers to reproduce, in his exact words, "a complete, directional, sound picture".
Kris.
A few days ago I read a new post on the "Adventures in High Fidelity Audio" blog, http://www.adventuresinhifiaudio.com/15/06/2010/real-stereoturn-me-up-and-save-fm-three-very-worthwhile-causes/ and frankly, what was written saddened me greatly. Although well meaning, it only reinforces the misinformation, and hence prompted me to write this post.
True stereophonic sound, as devised by Blumlein
What does TNT-Audio actually mean by 'true Stereophonic sound'? I think their webpage is quite clear on the matter, two discrete channels each feeding one speaker.
I think we have to take this definition as read, especially considering that if you ask most people what 'stereo' means they'll reply something along the lines of “two channel sound”.
Within the bounds of this TNT-Audio definition then, Blumlein did not invent or devise Stereophonic sound. Sorry, but he DID NOT. And in writing this post, I'm trying to set the record straight.
Firstly let’s look at the definition. Stereophonic sound does NOT mean two chanel two speaker sound. What it means is:
Stereophonic sound, commonly called stereo, is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing.
Yes, stereophonic sound is the reproduction of sound using two OR MORE channels (and hence speakers). Stereophonic sound therefore is multichannel sound. And this is exactly what Blumlein created.
Actually, his patent doesn’t even mention stereo or stereophonic. The term was invented by Western Electric and popularised by Decca. The term 'stereo' cannot be attributed to Blumlein. And actually, apparently, not once in any of his writings or patents does he use the term. Blumleins patent is all about recording and reproducing binaural sound using a 'plurality' of speakers. I.E. more than one, and not necessarily two
If you don’t believe me, go read his patent yourselves. It’s available online at http://www.doramusic.com/patents/394325.htm
the invention consists in a method of transmitting, recording and/or reproducing sound wherein a plurality of transmission channels so interact, each upon each, or are in such relation or so relatively modified in combination and subsequently re-separated, that the complete intelligence initially transmitted is further conveyed, differently arranged, between the channels.
He goes further than that. In his patent he even described using multiple channels and multiple speakers to capture and reproduce HEIGHT.
The TNT-Audio 'Support Real Stereo' webpage champions Blumlein, which is great, but they appear not to have read, let alone understood his patent. Furthermore, throughout their blurb they completely misrepresent his views, his patent, and his far-sightedness:
With just two correctly designed and positioned microphones
the invention is not limited solely to the use of two microphones
Ironically, the consumer electronics industry, which was given such a gift in the invention of stereo, is now shifting its attention more towards home theatre and the multi-channel sound developed primarily for that medium.
It will be clear that the invention is particularly applicable to talking motion pictures and the following description will therefore be given with reference to this application.
TNT talk about irony when the actual real irony is totally lost on them. Yes, multichannel sound, as devised by Blumlein, was specifically intended for use in the film industry! He even had the idea whilst in the cinema watching a film with his wife!
True stereophonic sound, as devised by Blumlein, is quite capable of reproducing such an event with just two channels and two loudspeakers, so why complicate the issue with more channels and more speakers?
It really is unbelievable. They champion Blumlein then ask why use more than two channels and speakers! Here's what Blumlein says:
The above described system is based upon consideration in which no account is taken of sound reflections of interference either during recording or reproduction. If difficulties arise from this cause they may be overcome by employing a second pair of loud speakers differently spaced and having a different modifying network from the first pair: or a row of speakers may be used with a composite, progressive modifying network to supply them
(My bold).
Why complicate the issue with more than two speakers? Because Blumlein foresaw and made allowances for it. Throughout his patent he actively encourages the use of more than two speakers. Why? It's quite simple and straightforward - two speakers cannot accurately reproduce (using Blumleins phrase) "a complete directional sound picture".
You see, Blumleins vision was to record the sound field created in a given space, using a plurality of microphones and reproduce that sound field using a plurality of loudspeakers. Recreating using multiple microphones and loudspeakers, the sound field otherwise obtained and reproduced binaurally. And binaural is surround sound!
Notice I'm saying 'sound field', not 'sound'. Sound field (a modern term which means roughly the same as Blumleins 'sound picture') refers to the complete three dimensional sound produced in a given space - up, down and behind, as well as from the front. So, for example, when recording an orchestra, in order to capture the sound field, one doesn't actually mic up and record the orchestra, but record the sound produced in that room while the orchestra is playing. Which is actually what Blumlein was describing in his patent. he even experimented with placing his microphones in different places in the room, far away from the band or orchestra. He was trying to capture the entire sound created in the room. In his patent he even discusses capturing and reproducing the sound created from beyond the edges of the screen.
As you know, our ears pick up sound from all around us. And when we are listening to a live concert or whatever, we are hearing the sound that is produced in that room. Both the direct sound from the players, and the indirect sound that bounces off the walls and reverberates around the room.
Stand in the middle of a group of people - you will hear sound from all around you, behind, above, and below, as well as from in front of where you are standing. Which is why Alan Blumlein was interested in obtaining: "a complete directional sound picture".
So if indeed this is so, then why doesn't Blumlein specifically mention capturing sounds from the rear? Well, Blumleins patent was so futuristic and out of the box that few people of the time could understand what he was talking about in the first place. He even had to write a few papers trying to explain his invention in plainer English. Secondly, Blumlein was primarily concerned with the transmitting and storage of two channels, to record and reproduce sounds from multiple directions, using multiple mics and multiple speakers. And it was hard enough to do encode these two channels into one record groove, let alone more than two channels! And thirdly, he had to stop work on his audio inventions in order to concentrate on more pressing issues of the day. However, even if he didn't specifically mention it, his patent is chock-a-block full of clues that point to how he would have progressed his audio experiments had he been able to.
He was very aware of sounds from the rear - which binaural recording picks up just as well as sounds from the front. The microphone and mic technique he devised was a surround sound one - a crossed pair figure of 8 which picks up sound from 360 degrees, the rear sound being reproduced out of phase, which he was well aware of and even allowed for by saying that if the sound reflections interfere with the reproduction, one can use a second pair of loudspeakers differently spaced and with a different modifying network. Without realising it, Blumlein had invented surround sound! And actually, many people (including the BBC) recognise this patent of Blumleins as being a Surround Sound patent. This is especially true not just because of his surround sound mic, but also his mentioning of the capture, recording and reproduction (using additional channels & speakers) of height information.
Now I have to admit, in this patent he was primarily concerned with accurate sound location in relation to what was happening on the movie screen, and in this regard he does say that we will naturally discount any sound not coming directly from the visual sound source. But then again, the movie screen was in front of him, Imax hadn't been invented back then!
Unfortunately Blumlein didn't have a crossed pair figure of 8 mic to work with in his experiments. If he had I am in no doubt that one of his next steps would have been to investigate the out of phase sounds coming from the rear and to place the mic in the middle of the room and have his assistants walk around the mic in a circle, whilst reproducing that sound in the downstairs auditorium using four loudspeakers. I feel it's one of the main reasons he devised the cross figure of 8 mic technique. After all, he does go into detail about the phase differences captured by the mics, and that his technique was to capture the echoes produced in a room and to be reproduced with directional significance.
To my ear only Stereo does that, as it presents the music in a believable 3 dimensional space before you, the listener, with both image width left to right, image height and image depth.
Yes, two speaker stereo does present sound in a believable 3 dimensional space before you. But natural sound doesn't just come from the front. It comes from all around us. Respectfully, two speaker stereo can never accurately reproduce an entire sound field. That's not my opinion, it's a fact. Two speaker front positioned stereo cannot accurately spatially reproduce the sound of someone sitting behind you, or above you, or below you. The only way to accurately do this (apart from binaurally) is to have a plurality of speakers positioned not only in front of you, but behind, above, and below you, reproducing a signal which has (genuinely, not artificially) captured the entire sound field.
Of course, as soon as someone mentions surround sound, one automatically thinks of 'Dolby Surround' or whatever is the flavour of the month. 2.1 5.1 7.1 9.1 etc. Frankly I am no fan of these flavours of surround sound. These are discrete systems where the sounds are purposely recorded and pushed to certain speakers. The result is mostly a false and manufactured sound field.
That said, there is an accurate way of recording a sound field (including height) into two channels. And it's a system that used by football broadcasters around the world, the BBC and many others, even some computer game producers. It's called Ambisonics.
Nimbus record all their material in Ambisonics and as they say, Ambisonics "remains unchallenged as the most coherent and effective Surround Sound system". Which is why broadcasters around the world use it.
The problem is that domestic surround sound systems can't decode an ambisonic signal, so the broadcasters have to recode the ambisonic fomat into discrete Dolby surround sound, or whatever format is the flavour of the month.
Which is a great great shame. Ambisonics is not restricted to a certain number of loudspeakers. The signal can be decoded into 4, 6, 7, 8, 12, or even 200 speakers - including any number positioned above and below your listening seat.
The other big plus with Ambisonics is that there is no 'hot seat'. As it records and reproduces the sound field of the room in which the microphones are placed, you can walk around anywhere in your listening space and still be within the sound field, just as you can walk around anywhere inside a concert hall and still be within the sound field.
The other big bonus is that an Ambisonic recording is usually of much higher quality than other systems as it's more direct mic to recording - you don't need a big recording console and you don't need to artificially change the sound in any way. yes, Ambisonics can be, and generally is, of audiophile quality.
I've been using Ambisonics for many years. I've even got an ambisonic decoder in my car. Have had for decades. (That said, I don't have any speakers above or below me!)
And no, I don't just use it to decode Ambisonic signals. It's surprisingly capable of decoding virtually any surround sound signal. Including the Pink Floyd Holophonics. If you've not heard Pink Floyd or a Nimbus CD or record, or especially the Cowboy Junkies Trinity Sessions etc, through an Ambisonic (or other genuine non-discrete decoder) you've not heard it how it was intended to be heard. And it really is amazing. NO two-speaker system can reproduce it anywhere near accurately.
When reproducing non-surround sound material, yes, it's a bit hit and miss. Modern pop music or heavily multitracked music doesn't reproduce well, so I just switch it off. But simply recorded music, be it folk, jazz, choral, classical etc mostly sounds amazing. Far better, to my ears, than any two-channel system can reproduce it.
we declare that what we claim is: A sound and picture reproducing system . . . wherein the relative volumes of the reproducing loud speakers are so controlled as to provide apparent location of the sound original in coincidence with the optical location of the image from which the sound is supposed to emanate.
Now, can anyone who has actually READ his patent with an open mind really interpret this as meaning 'real stereophonic sound' as specifically described & promoted by 'Support Real Stereo' campaign?
The truth of the matter is that 'stereophonic' sound is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing. And as in natural hearing that includes sounds coming from behind, above and below us! Anything else is unnatural.
I have absolutely nothing against anyone who supports high quality two speaker stereo sound reproduction. And yes, I fully, completely agree that these modern all in one 'surround sound' systems are a total waste of space and money and do nothing to further the cause for good quality sound. However, that said, I hope I have shown that the information presented on the 'Real Stereo' webpage http://www.tnt-audio.com/topics/realstereo_e.html regarding his invention is inaccurate and, frankly, in my opinion, a disgrace to the memory of Alan Blumlein, a genius who didn't invent or devise solely two speaker sound reproduction but specifically decreed & intended his patent to be a starting point in multi-speaker sound recording & reproduction chain, foreseeing a future where people would use a plurality of microphones and a plurality of loudspeakers to reproduce, in his exact words, "a complete, directional, sound picture".
Kris.