bigshot
Headphoneus Supremus
are you advocating that intelligent, informed and truth-seeking people should accept any old made-up unsubstantiated theory or BS?
That's what analoguesurvivor does. He's just following the trend.
are you advocating that intelligent, informed and truth-seeking people should accept any old made-up unsubstantiated theory or BS?
All true. And the solution couldn't be more simple, for KeithEmo to support his claims with some evidence, or are you advocating that intelligent, informed and truth-seeking people should accept any old made-up unsubstantiated theory or BS?
G
That's what analoguesurvivor does. He's just following the trend.
You've got most of the basic facts more or less right.... but you've sort of missed some of the details and the consclusions.
It's well established that many things produce some output up to and including very high frequencies.
For example, even a relatively clean 1 kHz square wave produces harmonics into the megahertz (theoretically up to infinitely high frequencies).
In fact, many complex waveforms contain harmonics that theoretically extend to infinitely high frequencies.
(Many old style LED displays were chopped using a square wave at a few hundred Hz.... and produced harmjonics high enough to interfere with AM radios.)
And things like a cymbal hit contain at least some components reaching into the very high ultrasonic range.
And that information is PRESENT... whether we humans can hear it or not.
The argument about "whether high-res recordings are audibly different" focuses on whether those sounds may in fact be audible to some people.
HOWEVER, exlcuding for the moment whether anyone can HEAR them or not, those high frequency components can be used to obtain OTHER information.
For example, by analyzing the arrival times of echoes of some of those high frequencies, we may be able to tell how large the studio was, and what it was made of.
When someone hits a cymbal, we can tell what the walls and floor were made of by analyzing the spectrum of the echoes....
For example, concrete floors absorb certain frequencies more thoroughly than others, and wood walls act differently.
So, by comparing the spectrum of the original hit, to the spectrum of the echo, we can tell what the wall was made of by comparing the amounts of various frequencies present in both.
As a simple example, if the original cymbal hit was bright, but the first echo sounded dull, then the wall that first echo bounced off of was probably padded.
And, if that first echo was bright, then that wall was probably very reflective.
(And we can tell how far away the wall was by measuring the delay between the first hit and the echo.)
This gives us INFORMATION about where that cymbal was recorded.
That information may them be useful for something (other than listening to).
Maybe I juts want to know abut the studio.
Oe, maybe, the vocalist sounds as if she was recorded in a different room.
By knowing what both rooms were like, I can add some specific reverb to the vocals, and make them sound like they were recorded in the same room as the cymbals.
And, more to the point of what I was saying....
A modern surround sound processor mught use information like that to learn about the original venue so as to adjust its operation in some fashion.
I pointed out that we already DO have processes that use inaudible information for quite useful purposes.
Click-and-pop reducers use ultrasonic information to tell record clicks from sounds recorded in the music.
The Plangent process uses inaudible high-frequency residual record bias to correct tape flaws.
The ICE optical process uses invisible infrared components to accurately tell the difference between scratches on a photo negative and lines that are part of the actual photo.
The list goes on and on, and I merely suggested that some of the information that is obviously present in those recordings may well prove useful - even in "consumer gear".
(You might be amazed how much computer processing goes into, for example, synthesizing height channels from a two-channel recording.)
Perhaps next week's surround decoder will use that information it figures out about the studio to make more accurate height speaker channels...
If so, then it will work much better with recordings that have retained that information than with those that haven't.
I don't know... and neither can anyone else.
[1] Keith's point about sonar being a useful technology indoors does prove that reflected ultrasound is reliably detectable in normal spaces. Not all recording venues completely lack surfaces that might return some reasonable-amplitude ultrasound to the mic's position.
[2] If the wall is 3 meters from the musician, we might get (say) 6dB attenuation from the air plus (say conservatively) another 20dB from the reflection, for all I know at -26dB the 24khz crap coming off a cymbal is still an intelligible signal for some arbitrary purpose.
Because you're so sure you're right and can't see any other possibility, you're not seeing that judging what's "unsubstantiated theory" and "BS" is sometimes a matter of perspective.
Probably 99% of commercial audio recordings are not supposed to acoustically sound anything like the actual acoustic space they were recorded in. KeithEmo could hardly have picked a worse area to push his ultrasonic agenda because he can't even show there is any acoustic info there, let alone how to differentiate and analyse it or how it could be useful even if we could overcome all of these impossibilities!
G
This is a good response overall, I don't disagree on any of it really. I would think it goes without saying that you basically wouldn't bother looking for ultrasonics from anything except percussion.
When it comes to drums / cymbals, I could imagine an algorithm that might do something interesting using ultrasonic content.
Since that band will be relatively free from interference from anything except percussion, you might be able to use the cymbals to approximate some kind of impulse response and then derive the size / composition of the space based on certain assumptions (rectangular room, for example), and from there generate some kind of useful "clean" IR?
From other comments, I gather this is already attempted by some software, but I don't have any idea of how well it works. And it seems more like a novelty for producers / engineers than something a consumer would want, but it's sort of fascinating to think about.
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None of this suggest any utility in recording ultrasonics.
Also nothing in his writing is backed up by any evidence that calculating the acoustics or structure of the original venue would be beneficial to the reproduction of the record.
MQA is a good example of the fact that audiophiles demand impossible things and the fact that unscrupulous companies who pretend to serve them the moon on a plate succeed over engineers who try to deliver actual improvements on an everyday basis.
[1] And, yes, the echoes of bat signals do contain acoustic information...And bats do use them to collect data about things like... where the walls are... and what they're made of. And, yes, they seem to be somewhat better at analyzing that data than we are... at least for now.
[2] No.... I'm really done being baited into responding this time
Because you're so sure you're right and can't see any other possibility, you're not seeing that judging what's "unsubstantiated theory" and "BS" is sometimes a matter of perspective.
[1] I would think it goes without saying that you basically wouldn't bother looking for ultrasonics from anything except percussion.
[2] When it comes to drums / cymbals, I could imagine an algorithm that might do something interesting using ultrasonic content. ...
Now, let's assume I have a multi-track recording of a vocalist singing with a band...
The band was recorded in a large room, but the vocalist was recorded in a sound booth at the studio, and mixed in later.
It's obvious that, at least to begin with, the background tone of the band's performance isn't going to match that of the vocalist.
If the band recorded in a cathedral, there will be echoes of the drums from the walls, and other sorts of "venue ambience".
However, those room size cues will be missing from the vocal track (there won't be any of those echoes in the vocal track because the vocalist wasn't singing there).
If the mix was well mastered, the engineer will have added reverb to the vocal track to match the ambience associated with the music.
He'll have used a plugin to create echoes and other ambience in the vocal track to make it seem as if the vocalist was singing in the same room as the band was playing.
And, if that wasn't done, some humans might complain that the recording sounded quite unnatural, and was "obviously multi-tracked".
A few recent mastering plugins offer the ability to fix this automatically, by "extracting the tone from one track and applying it to another".
If you've been keeping track, you'll realize that there is a long history of including various "DSP modes" in home theater processors.
Most of them simulate the sounds of specific types of rooms by adding processing to the audio.
Yamaha was well known for offering DSP modes like "concert hall" and "cathedral" as options on their home theater gear.
Could someone sell a new product that include a DSP algorithm that "made unnatural sounding recordings sound more natural"?
The answer there is an obvious yes... because many such products already exist.
Could such an algorithm make use of information about the original venue where most of the tracks were recorded to do a better job?
I'll bet it could.