6 ms·

This comment covers much of what is wrong with common interpretations of acoustics. > the human ear is largely insensitive to moderate variations in volume/fr

by mbell 12y ago

This comment covers much of what is wrong with common interpretations of acoustics. > the human ear is largely insensitive to moderate variations in volume/frequency... but it's incredibly sensitive to phase. No, it's not. The human auditory system is sensitive to time variation. Phase shift may contribute a time shift but only at frequencies low enough that their wavelength has reasonably relation to the spacing of the ears. For example at 10Khz the wavelength is far too short for 'phase' to impact arrival time. Ultimately what actually matters in this regard with the human auditory response is group delay, not phase. > Phase is how we discern directionality (stereo), among other things. As mentioned above, what matters in the context of what your saying is group delay, but that is far from the only thing that matters for directionality. The human psycoscoutic system is very complex, part of directionality is group delay, part of it is frequency attenuation caused by sound wrapping around the ear from the ear, part of it is a half dozen other things. 'Phase' doesn't come even close to being a catch all cause. > To my ears, the best and most musical sounding speakers And thus we've devolved from science, as this usually goes. What on earth does 'musical sounding speakers' even mean? > It's very easy to measure frequency response. It's very hard to measure phase alignment. I have no idea where you came up with this statement but it is very easy to measure the response of a loudspeaker, both in amplitude and phase. > If you want to see serious map-over-territory thinking, look at THD specs for amplifiers. It's super-easy to measure THD - just isolate harmonics of a sine wave a 1khz. THD can be measured at only 1Khz, but it isn't something intrinsic to what 'THD' means. Measuring at only 1Khz is generally indicative of a crappy amplifier manufacturer looking to inflate their power numbers. Proper specs will provide a 20-20kHz THD rating. > Dynamic recovery behavior, intermodulation distortion, stuff like this is what gives amps their distinctive sounds - but it's nearly impossible to measure! If an amp has a distinctive sound, it has failed to achieve it's core design goal. I'm not sure what you think is impossible to measure, but I assure you it is not.

digitailor 12y ago
Both your comments are heavyweight so I'm not trying to pick sides. (Sum your two perspectives and I think you're close to Ultimate Expert Comment.) I just want to mention that beat is talking about phase alignment between identical signals, which our perceptual network is incredibly sensitive to. Anyone who has ever done multi-mic recording can attest to the very real effect you can hear from lack of phase alignment, even if they have bronze ears. Even worse is if you duplicate two musical recordings and offset one, even by a tiny amount. This is a critical aspect of crossovers- since they contain the same signal, any phase differences between the intersecting components are easy to pick up by the ear and very difficult to measure since it won't show up as a significant frequency or amplitude differential. In the highly acoustically sensitive area where the crossover occurs, the phase distortion between the two signals is hard to pin down but it's definitely there, it's easy to hear by A/Bing. I mix on a multiple-monitor setup and the one that is most critical to me sounds like absolute garbage. However, it has a wonderfully "flat" response and allows you to get an idea of what proven aesthetically-unpleasing issues are present. It has no crossover. The goal is not to have perceived rumble, tinniness, or mud on any of the incredibly wide range of listening systems out there. I think this is what beat means by "musical"- flat speakers are actually not pleasant to the ears, but the most empirically useful. The most famous secret of many respected mix engineers is the Auratone. Michael Jackson's "Bad" was mostly mixed on this little thing. It sounds like absolute garbage aesthetically but reveals more issues in a mix than anything else. It's like when you first saw things under a "blacklight" as a kid and got to see all the particulate matter covering everything, that you can't see with the naked eye. Here's more about the Auratone. I hope my comment has helped to bridge this critical area of "musicality" vs. empiricism. http://www.trustmeimascientist.com/2012/02/06/auratone-avantone-behritone-review/ http://www.trustmeimascientist.com/2012/02/06/auratone-avant... Postscript- the listening environment is the most important aspect! Always! You can have the best mastering grade monitors on earth in an improperly treated room, and it's all for naught!
- mbell 12y ago
  > I just want to mention that beat is talking about phase alignment between identical signals, which our perceptual network is incredibly sensitive to. I wouldn't go that far. If you have two signals emitting from physically separate location and they are out of phase, you just get comb filtering. Is it audible? It can be, but its not the phase you're hearing, it's the drastic frequency notching in amplitude. More importantly, you're going to get comb filtering no matter what you do with a multi-speaker setup. Just move your head a couple inches out of the ideal sweet spot equidistance from each speaker and you'll have created an effective phase shift and get the same type of comb filtering. In other words even with a theoretically perfect pair of time aligned speakers with perfect cross-overs, you'll still get comb filtering if you take various measurements around the listening area. Just moving the mic 4 inches can have drastic effects on the measured response. Incidentally if you've ever seen someone taking a measurement with a sound meter and rhythmically moving the mic around in a strange fashion, they are doing that to try to even the effects of comb filtering. > This is a critical aspect of crossovers- since they contain the same signal, any phase differences between the intersecting components are easy to pick up by the ear and very difficult to measure since it won't show up as a frequency or amplitude differential. If you're taking a measurement in the crossover region and there is a phase shift between the drivers you most certainly will see an effect in amplitude as you'll have at least partial wave cancellation. You can certainly take measurements in locations what won't show this, but that is always true. You can take measurements of a perfectly time aligned speaker that make it look like it has phase issues too, if you put the mic in the right spot. Likely the largest improvement you get from time alignment of the drivers in a multi-way speaker is the ability to control vertical lobe tilting, but you can 'fix' that issue with MTM layouts without time aligning the drivers as well.
  - lcrs 12y ago
    I think what one might crudely call the "audiophile phase beef" is not about the comb-filtering that results from misalignment but the non-linear phase response of most crossovers, before the signal hits the air. Most act somewhat like an all-pass filter: a flat frequency response but varying delay across the frequency spectrum. This doesn't affect frequency sweeps or white noise, but results in impulses and clicks being smeared out in time or ringing a bit. The thought among some is that this is audible on percussion sounds, but experimental evidence is dubious as far as I can see. There are some references in the classic Douglas Self crossover book: http://books.google.co.uk/books?id=D9l6JWKKSzUC&lpg=SA2-PA14&ots=wEtgaIUCgH&pg=SA2-PA22#v=onepage&q&f=false http://books.google.co.uk/books?id=D9l6JWKKSzUC&lpg=SA2-PA14... A similar argument which I think more people would agree with is that reflex-loading a speaker hurts the low-frequency group delay, the lack of which is one reason suggested for the supposed clarity of the classic NS10 monitor: http://www.soundonsound.com/sos/sep08/articles/yamahans10.htm http://www.soundonsound.com/sos/sep08/articles/yamahans10.ht...
beat 12y ago
I'm not devolving from science. I'm pointing out that science is insufficiently evolved to truly understand the domain. I'm a musician and a recording engineer. I've made records, I listen to real-world instruments every day, I've built speakers, and I've built amplifiers. And I've learned along the way that "accurate" is a big stinking pile of BS, and "scientific" is usually just a euphemism for magical thinking - "If we can't measure it, it doesn't exist". If you can't measure it, maybe you don't understand the problem as well as you thought. You don't get to ignore the evidence of the senses of domain experts just because it makes you uncomfortable.
tlarkworthy 12y ago
I think you are wrong to dismiss domain experts opinions as leaving science. Machine learning 101 is eye ball your data, as the human brain is the most powerful pattern matcher known. A musicians ear is therefore the best tool for detecting anomolies in sound and should not be dismissed for not having a nice mathematical construction. Acoustics are perceptual and are heavily filtering the real world sound waves so I don't think its possible to reduce the laudatory cortex to simple filters like its ignoring phase or whatnot.
- DanBC 12y ago
  > A musicians ear is therefore the best tool for detecting anomolies in sound This is only true if you can remove biases.
  - beat 12y ago
    Gah, not A/B testing nonsense. Want an A/B test? Put your hi-fi in the same room with a real singer, or an acoustic guitar, or whatever musical instrument, and see how hard it is to tell them apart. Not very, I assure you. Interestingly, we can pick up very subtle and useful musical cues from very poor recordings and reproduction. It's a complex thing.
jacquesm 12y ago
> For example at 10Khz the wavelength is far too short for 'phase' to impact arrival time. It's the time-of-flight difference between when the one ear receives the wave front and the other from a change in the sound that gives us the directional information. Absent any change all we have to go on is volume so we rotate our heads to the point where both ears receive the signal equally strong, then the source is somewhere in the plane that bisects the head of the listener. Rotating one ear forward gives us the clue about whether the sound source is in front of us or behind us. (Fails to work when it is directly overhead.)
- Anechoic 12y ago
  It's the time-of-flight difference between when the one ear receives the wave front and the other from a change in the sound that gives us the directional information. That's part of it, the other part is the head related transfer function is the change in response of sound due to diffraction effects caused by the head, upper torso and pinnae. The pinnae also help us to judge elevation.
ricardobeat 12y ago
> If an amp has a distinctive sound, it has failed to achieve it's core design goal. What makes you think the design goal of an amp is always to have perfect sound reproduction? That may be true for a home-theater system or if you're playing wind/string instruments, not so for a guitar amp. We have the (digital) tools to get pure, 100% uncolored sound, and musicians hate it.
- sp332 12y ago
  These are "bookshelf monitors", and the whole point of a monitor is to be accurate!
  - ricardobeat 12y ago
    The comment to which I replied to was an absolute statement, not referring to the monitor built. Maybe if he had said "If a monitor has a distinctive sound [...]" that might have been closer to truth; in practice it's nearly impossible not to have a distinctive sound, there are too many variables at play.
    - epsylon 12y ago
      > in practice it's nearly impossible not to have a distinctive sound, there are too many variables at play. Of course not. High-end monitors are high-end precisely because they achieve indistiguishability. Between to pairs of speakers from different brands, you wouldn't be able to tell the difference.
      - ricardobeat 12y ago
        Are they? I haven't had the chance to compare two monitors in the same room, but as far as I know no two are alike, and none has ever achieved a perfectly flat response curve. Take also high-end headphones, where it's way easier to have a similar acoustic profile, yet any two models with similar characteristics (on paper) are very easy to tell apart.

by mbell 12y ago

digitailor 12y ago

Both your comments are heavyweight so I'm not trying to pick sides. (Sum your two perspectives and I think you're close to Ultimate Expert Comment.) I just want to mention that beat is talking about phase alignment between identical signals, which our perceptual network is incredibly sensitive to. Anyone who has ever done multi-mic recording can attest to the very real effect you can hear from lack of phase alignment, even if they have bronze ears. Even worse is if you duplicate two musical recordings and offset one, even by a tiny amount. This is a critical aspect of crossovers- since they contain the same signal, any phase differences between the intersecting components are easy to pick up by the ear and very difficult to measure since it won't show up as a significant frequency or amplitude differential. In the highly acoustically sensitive area where the crossover occurs, the phase distortion between the two signals is hard to pin down but it's definitely there, it's easy to hear by A/Bing. I mix on a multiple-monitor setup and the one that is most critical to me sounds like absolute garbage. However, it has a wonderfully "flat" response and allows you to get an idea of what proven aesthetically-unpleasing issues are present. It has no crossover. The goal is not to have perceived rumble, tinniness, or mud on any of the incredibly wide range of listening systems out there. I think this is what beat means by "musical"- flat speakers are actually not pleasant to the ears, but the most empirically useful. The most famous secret of many respected mix engineers is the Auratone. Michael Jackson's "Bad" was mostly mixed on this little thing. It sounds like absolute garbage aesthetically but reveals more issues in a mix than anything else. It's like when you first saw things under a "blacklight" as a kid and got to see all the particulate matter covering everything, that you can't see with the naked eye. Here's more about the Auratone. I hope my comment has helped to bridge this critical area of "musicality" vs. empiricism. http://www.trustmeimascientist.com/2012/02/06/auratone-avantone-behritone-review/ http://www.trustmeimascientist.com/2012/02/06/auratone-avant... Postscript- the listening environment is the most important aspect! Always! You can have the best mastering grade monitors on earth in an improperly treated room, and it's all for naught!

mbell 12y ago
> I just want to mention that beat is talking about phase alignment between identical signals, which our perceptual network is incredibly sensitive to. I wouldn't go that far. If you have two signals emitting from physically separate location and they are out of phase, you just get comb filtering. Is it audible? It can be, but its not the phase you're hearing, it's the drastic frequency notching in amplitude. More importantly, you're going to get comb filtering no matter what you do with a multi-speaker setup. Just move your head a couple inches out of the ideal sweet spot equidistance from each speaker and you'll have created an effective phase shift and get the same type of comb filtering. In other words even with a theoretically perfect pair of time aligned speakers with perfect cross-overs, you'll still get comb filtering if you take various measurements around the listening area. Just moving the mic 4 inches can have drastic effects on the measured response. Incidentally if you've ever seen someone taking a measurement with a sound meter and rhythmically moving the mic around in a strange fashion, they are doing that to try to even the effects of comb filtering. > This is a critical aspect of crossovers- since they contain the same signal, any phase differences between the intersecting components are easy to pick up by the ear and very difficult to measure since it won't show up as a frequency or amplitude differential. If you're taking a measurement in the crossover region and there is a phase shift between the drivers you most certainly will see an effect in amplitude as you'll have at least partial wave cancellation. You can certainly take measurements in locations what won't show this, but that is always true. You can take measurements of a perfectly time aligned speaker that make it look like it has phase issues too, if you put the mic in the right spot. Likely the largest improvement you get from time alignment of the drivers in a multi-way speaker is the ability to control vertical lobe tilting, but you can 'fix' that issue with MTM layouts without time aligning the drivers as well.
- lcrs 12y ago
  I think what one might crudely call the "audiophile phase beef" is not about the comb-filtering that results from misalignment but the non-linear phase response of most crossovers, before the signal hits the air. Most act somewhat like an all-pass filter: a flat frequency response but varying delay across the frequency spectrum. This doesn't affect frequency sweeps or white noise, but results in impulses and clicks being smeared out in time or ringing a bit. The thought among some is that this is audible on percussion sounds, but experimental evidence is dubious as far as I can see. There are some references in the classic Douglas Self crossover book: http://books.google.co.uk/books?id=D9l6JWKKSzUC&lpg=SA2-PA14&ots=wEtgaIUCgH&pg=SA2-PA22#v=onepage&q&f=false http://books.google.co.uk/books?id=D9l6JWKKSzUC&lpg=SA2-PA14... A similar argument which I think more people would agree with is that reflex-loading a speaker hurts the low-frequency group delay, the lack of which is one reason suggested for the supposed clarity of the classic NS10 monitor: http://www.soundonsound.com/sos/sep08/articles/yamahans10.htm http://www.soundonsound.com/sos/sep08/articles/yamahans10.ht...

beat 12y ago

I'm not devolving from science. I'm pointing out that science is insufficiently evolved to truly understand the domain. I'm a musician and a recording engineer. I've made records, I listen to real-world instruments every day, I've built speakers, and I've built amplifiers. And I've learned along the way that "accurate" is a big stinking pile of BS, and "scientific" is usually just a euphemism for magical thinking - "If we can't measure it, it doesn't exist". If you can't measure it, maybe you don't understand the problem as well as you thought. You don't get to ignore the evidence of the senses of domain experts just because it makes you uncomfortable.

tlarkworthy 12y ago

I think you are wrong to dismiss domain experts opinions as leaving science. Machine learning 101 is eye ball your data, as the human brain is the most powerful pattern matcher known. A musicians ear is therefore the best tool for detecting anomolies in sound and should not be dismissed for not having a nice mathematical construction. Acoustics are perceptual and are heavily filtering the real world sound waves so I don't think its possible to reduce the laudatory cortex to simple filters like its ignoring phase or whatnot.

DanBC 12y ago
> A musicians ear is therefore the best tool for detecting anomolies in sound This is only true if you can remove biases.
- beat 12y ago
  Gah, not A/B testing nonsense. Want an A/B test? Put your hi-fi in the same room with a real singer, or an acoustic guitar, or whatever musical instrument, and see how hard it is to tell them apart. Not very, I assure you. Interestingly, we can pick up very subtle and useful musical cues from very poor recordings and reproduction. It's a complex thing.

jacquesm 12y ago

> For example at 10Khz the wavelength is far too short for 'phase' to impact arrival time. It's the time-of-flight difference between when the one ear receives the wave front and the other from a change in the sound that gives us the directional information. Absent any change all we have to go on is volume so we rotate our heads to the point where both ears receive the signal equally strong, then the source is somewhere in the plane that bisects the head of the listener. Rotating one ear forward gives us the clue about whether the sound source is in front of us or behind us. (Fails to work when it is directly overhead.)

Anechoic 12y ago
It's the time-of-flight difference between when the one ear receives the wave front and the other from a change in the sound that gives us the directional information. That's part of it, the other part is the head related transfer function is the change in response of sound due to diffraction effects caused by the head, upper torso and pinnae. The pinnae also help us to judge elevation.

ricardobeat 12y ago

> If an amp has a distinctive sound, it has failed to achieve it's core design goal. What makes you think the design goal of an amp is always to have perfect sound reproduction? That may be true for a home-theater system or if you're playing wind/string instruments, not so for a guitar amp. We have the (digital) tools to get pure, 100% uncolored sound, and musicians hate it.

sp332 12y ago
These are "bookshelf monitors", and the whole point of a monitor is to be accurate!
- ricardobeat 12y ago
  The comment to which I replied to was an absolute statement, not referring to the monitor built. Maybe if he had said "If a monitor has a distinctive sound [...]" that might have been closer to truth; in practice it's nearly impossible not to have a distinctive sound, there are too many variables at play.
  - epsylon 12y ago
    > in practice it's nearly impossible not to have a distinctive sound, there are too many variables at play. Of course not. High-end monitors are high-end precisely because they achieve indistiguishability. Between to pairs of speakers from different brands, you wouldn't be able to tell the difference.
    - ricardobeat 12y ago
      Are they? I haven't had the chance to compare two monitors in the same room, but as far as I know no two are alike, and none has ever achieved a perfectly flat response curve. Take also high-end headphones, where it's way easier to have a similar acoustic profile, yet any two models with similar characteristics (on paper) are very easy to tell apart.