Interesting. I remember before stereo audio was available on TV in the UK, there would often be concerts and similar broadcast with video on BBC 1, where you muted the audio, and listened to simultaneous stereo audio on e.g. BBC Radio 3, which was a neat hack.
Interesting that he called it binaural recording, which is still a term today, but with slightly different connotations. That is, what I understand to be the common definition of binaural today is a recording done by a pair of microphones positioned like a person's ears with the goal of creating a fully 3D audio experience when listening through headphones. This is quite different from stereo meant to be listened to with a pair of stereo speakers. I wonder if what we today call binaural is really what Blumlein was envisioning.
Actually binaural is a special case of stereo [1]. Stereo means a recording with two microphones spaced apart. Binaural means a recording with two microphones spaced at the distance of a human head.
> Binaural means a recording with two microphones spaced at the distance of a human head.
I don't think that's enough. It's about the effect of the shape of the head and ears on the propagation of sound waves. For example, the definition of binaural in the page that you linked to says:
> the head and ear structure affect the way sound waves are picked up
Correct. I don't have one myself, but for high-end acoustic work people actually use dummy heads, sometimes with ballistic gel inside, to get a very good approximation of the sound that actually reaches the ears.
For less perfect results you could just set up measurement microphones in the right position and then convolve the result with a Head-Related Transfer Function.
They cost about $10,000 unfortunately. I'd love to have one for film use but you don't really get the effect except when listening with headphones so it's a pointless.
Also, for film we totally fake it and pan all the dialog into the center, on both stereo and surround mixes. Otherwise it would sound like the room was flipping around every time the camera cut back and forth between two actors during a dialog scene, which would get very disorienting for theatrical viewers. So when I build the audio for a dialog scene in post-production, I aim for an approximation of what you would hear if you were floating in the middle of the conversation just above people's heads. What you're hearing when you watch a movie bears little or no relation to the actual acoustics of wherever the scene was shot unless it was very quiet indeed, but is rather a composite of 10-20 different recordings.
> For less perfect results you could just set up measurement microphones in the right position and then convolve the result with a Head-Related Transfer Function.
This sounds interesting. Could you get to near-perfection by simply increasing the number of microphones used? Also, could using cheap microphones be compensated by using more of them?
>Could you get to near-perfection by simply increasing the number of microphones used?
No. Ears are (kind of) point sinks. Which is why dummy head stereo works so well on headphones - it's literally recording the sound that would usually go into your ears, as opposed to normal stereo, which records something that's usefully but rather distantly related to what goes into your ears.
Two microphones are enough for that.
A side point is that everyone has a slightly different HRTF, so it would be interesting to hear what you'd get with a neutral point sink recording convolved with your HRTF.
>Also, could using cheap microphones be compensated by using more of them?
No again. Cheap microphones add non-linear distortions and have a limited and inaccurate frequency response. If you use more cheap microphones you just get more of the same.
It's interesting, perhaps stereo was meant at the time for creating a more "3D" sound experience, stereo today remains the standard for recording music. Even though some movies and songs attempt things like including surround sound given that the technology now exists, stereo is much more common and full surround soundtracks are rare.
I'm curious if any audio engineers can weigh in on why stereo is still often all that is used today.
Pro sound engineer, in both music (long ago) and film.
Two basic reasons: one is that lots of people listen to music on headphones, and two is that most people don't set up their speakers properly. Even stereo speakers are usually not set up properly, and even most musicians don't set their speakers up properly. I don't set my speakers up properly at home. If you want them perfect you basically need to rearrange the entire room around that goal and my house isn't even quiet enough to make that effort worth it. Expecting people to set up a surround system just to listen to music? Forget it - as the lady said, ain't nobody got time for that.
In a movie theater, everything is placed pretty precisely and calibrated for a consistent level of loudness - although mroe and more these days, films tend to ignore established standards. Action movies are ludicrously loud and over-produced these days, for example, and directors like Michael Bay are notorious for demanding that playback levels be pushed into the red, resulting in genuine ear fatigue for many audiences.
At home, you can get nice results with a good home theater but again it depends how much time and money you want to invest in making it good. I just watch movies via the TV speakers because I don't want 6 more boxes with wires trailing all over the place, and between living in a somewhat noisy neighborhood and having a bunch of pets, the distractions to a great-sounding system would just be that much more distracting, if you see what I mean.
On the other hand, if I'm watching a movie in the theater and someone starts whispering near me I have no problem with telling them to shut up or get the fuck out in 99.9%* of cases. Having done it, I can tell you it takes weeks of painstaking work just to get an adequate competent soundtrack into shape, so the last thing I want to hear is some jackass 'explaining' it to his girlfriend like they're sitting in the living room.
* A very few movies benefit from vocal audience participation, and of course comedies are there to be laughed at.
One common error I come across a lot in home stereo installations is that people get the phase wrong on one of their speakers, even on very high end systems (or maybe especially there because those usually have their wires separated out).
We have two ears, so most of the psychoacoustic effects we experience in real life are achieved by just stereo recordings. Stereo listening also mimics the effect of standing in front of the stage at a live performance. You don't have performers on your back in real life. Also, stereo has a sweet spot, meaning that you only get to experience it properly when standing at the right distance in front of two speakers. Surround is similar in this way. All the other positions cancel almost all effects and it might as well be monophonic and we wouldn't notice.
So, while surround is interesting, it is not practical, the amount of mixing work needed is increased exponentially and for very little gain over stereo other than satisfying a very narrow audience. It's mostly a marketing gimmick in my opinion and a reason to sell hardware.
Add this to the fact that almost every equipment and technology since the discovery of stereo is designed to just handle stereo, I don't see us shifting to surround anytime soon. Binaural actually has a far better surround effect than surround audio. And it's in stereo.
>We have two ears, so most of the psychoacoustic effects we experience in real life are achieved by just stereo recordings.
That isn't quite true. Ears have no problem hearing up/down and front/back information.
Conventional stereo doesn't include those details. Alternative systems like Ambisonics do.
The real reason stereo is so popular is practicality. Two channels are more affordable and easy to distribute than six or twelve.
Even when people buy 5.1 surround, they usually compromise with dinky satellites and a big sub.
No-compromise surround certainly makes a difference, but for most people it's just not worth the extra money/space. It's a problem of diminishing aesthetic returns.
In fact you can get incredible positional effects out of multi-speaker systems that live in university engineering labs. But they're totally impractical for consumer use.
>That isn't quite true. Ears have no problem hearing up/down and front/back information.
>Conventional stereo doesn't include those details. Alternative systems like Ambisonics do.
Ears don't hear up/down and front/back. Ears hear left and right. The _brain_ uses information from tiny deviations of the sound which are caused by your head being in the way and then decodes it as being up/down and front/back.
This is what binaural sound is about, meaning, if you record in stereo something using earplug microphones, then listen to that recording using earplug headphones, those tiny deviations are present in that stereo recording and it'll cause your brain to determine the position of the sound source using that information. It's a psychoacoustic effect, like the reverb tells our brain the room characteristics a sound is played in. We don't actually need to be inside that room to playback a sound, we just add the reverb, the effect is good enough for our brains.
To me, the whole surround audio for consumers is a marketing gimmick because you can never get good enough and they can always keep selling newer and bigger speaker setups. The only adequate setup would be an anechoic spherical room, you sitting at the center and speakers in every direction possible. Surround as it is now has some practical use in motion pictures and mostly cinemas, to give you a somewhat feeling you're in the action, but it's not actually proper surround.
Actually the shape of the ears enhances that extra information. So it's not just psychoacoustic processing, and ears are not just wetware microphones.
>To me, the whole surround audio for consumers is a marketing gimmick
That's because Ambisonics - which hardly anyone has heard of now - never made it into the consumer mainstream. Of all possible surround systems, it's by far the best - precisely because done well, it can encode up/down and front/back information in a small number of channels.
Conventionally audio engineers won't try for above/back of head sounds in stereo but they're possible (samples exist online), if you're wearing headphones or standing in the exact intended position.
My dad is a pro engineer and has been trying to get people to adopt surround for a long time. He's done all of his recordings (mainly orchestra and chamber music) with stereo mics + surround mikes since the early 1990s but the producer usually mixes everything down to two channel formats.
However, my Dad still has all the multi-channel master files and loves to demonstrate them on his home system by switching the surround speakers on and off.
With the surround channels on and properly set up, you really do have more of a concert hall experience. E.g. the reverb of a loud drumbeat from the back of a hall actually seems to come from behind you.
This is totally subjective, but I would say the 2 channel version is 90% there, and the surround adds another 10%. It's a subtle, but pleasing effect.
Is it worth it? Probably not for most people, due to media space constraints (less of a problem now), the extra equipment and room configuration costs, and the fact that there is no good portable option.
Merely an amateur here who's done some demo tapes at the zenith of my career. But if I had to guess, it would be tied to how we listen to music live. In a _Transformers_ movie, as an example, you have explosions in front of you, missiles whizzing from behind, cars screeching from the left, etc. Surround sound is useful to create an immersive experience. The Beatles' White Album, meh, not so much. What, we'll put John and Paul up front, George rear left, and drums go...? Because that's not what you'd hear live. The Who tried quadraphonic sound on _Quadrapenia_, as did a few others back in the day. It obviously didn't go over big.
The simple answer is the more likely idea that iPod headphones only do two channels.
I'm fully hearing, but I never use a pair of headphones or earphones because I can't stand being unable to hear what's going on around me. So stereo is a similar annoyance to me. Fortunately some software lets you disable it.
The right channel and the picture were broadcast on the local NBC TV station, the left channel on an NBC Radio station.
My dad got everything set up for the broadcast: The TV on one side of the room, the radio receiver on the other. We tuned in and waited.
And then when George walked across the set, you could hear his voice move from one side to the other. It was so cool!