digital theory versus reality

[SoundAndMotion]

That would only be random in the phase domain. It is completely deterministic in the amplitude domain. And when the goal of the contest is to have a ruler flat FR, it's like saying you can have any random person build an audio amplifier that measures within 0.1dB from 20Hz to 20kHz, then saying you win because you added the condition that the random person is actually a random "audio electronics engineer with at least 10 years experience".

You're playing word games and I'm not interested. If I didn't tell you how I made it, and I just sent you a .wav, you could not find a definition that it would not comply with. It is created with a random (computer) process and meets the standard definition, but perhaps not your I-need-to-win-the-argument definition. I think you just want to back out of showing the the flying pig.

 

[Joe Bloggs]

I'm playing word games? A noise signal is supposed to be random. You take the only criterion we're interested in and insert the model answer straight from the cheat sheet. It has nothing in common with an authentic noise signal in the one criterion we're examining.

Here, have your real flying pig:


And again, if you did take the bother to do all this, I suggest you make a 64-sample block of this so-called "noise" and compare it in listening with an ideal impulse. You might be surprised how similar they sound :rolleyes:

 

[SoundAndMotion]

I'm playing word games? A noise signal is supposed to be random. You take the only criterion we're interested in and insert the model answer straight from the cheat sheet. It has nothing in common with an authentic noise signal in the one criterion we're examining.

You are. But let's stop this distraction of defining white noise (I still don't find your definition). My original point was "phase is important and cannot be ignored" when talking about the content of a signal. I make no claims about the role of phase distortion or audibility. I claim the description that the signal is completely described by the 2 values, amplitude and frequency, is false. Phase is required. If the phase is embedded in a complex variable, it is still 3 values: in the frequency domain (freq, real amplitude, imaginary amplitude). In the time domain, it is just amplitude and time, but you need twice the number of values (Nyquist)

p.s. I don't believe that pig is real, is it?

 

[johncarm]

The central issue is: how do we make good audio equipment?
 
Gregorio has been saying something to the effect that to make good equipment we need only consider "frequency and amplitude."
 
Sound Motion pointed out that this is incorrect because we also need consider phase.
 
I would further point out that Gregorio's semantics are garbled. To make a meaningful sentence about audio, you have to add a few more phrases. One possibility, and maybe this is what he's trying to say, is
 
"To characterize audio devices we need only measure the transfer function."
 
That would be a meaningful sentence. (It's not correct of course.)

 

[Joe Bloggs]

I'm playing word games? A noise signal is supposed to be random. You take the only criterion we're interested in and insert the model answer straight from the cheat sheet. It has nothing in common with an authentic noise signal in the one criterion we're examining.

You are. But let's stop this distraction of defining white noise (I still don't find your definition). My original point was "phase is important and cannot be ignored" when talking about the content of a signal. I make no claims about the role of phase distortion or audibility. I claim the description that the signal is completely described by the 2 values, amplitude and frequency, is false. Phase is required. If the phase is embedded in a complex variable, it is still 3 values: in the frequency domain (freq, real amplitude, imaginary amplitude). In the time domain, it is just amplitude and time, but you need twice the number of values (Nyquist)

p.s. I don't believe that pig is real, is it?

No it isn't. That's kind of the joke isn't it? Your white noise signal is just as real as my flying pig.

Actually, in the context of Hi-Fi reproduction, I've found it fine to leave the phase to fall where it may most of the time. E.g. it's been standard practice for me to put a 6 band multiband compressor in my playback chain and set the crossovers to 30dB/octave. It makes mincement of an ideal impulse but of course doesn't change the frequency amplitude response when it's not compressing. And I can't hear any effect it has on the audio when not compressing either. So I'd say gregorio's omission in this case, deliberate or not, is right on:

[1] Yes, my central question is what do we need to know to reproduce music with fidelity. [2] What is the definition of "superior musical performance"?

1. That depends on what you mean by music. If you mean acoustic sound waves, then as I've said repeatedly, amplitude and frequency. If you think there is something else, please answer the question and state what!!

G

 

[SoundAndMotion]

No it isn't. That's kind of the joke isn't it? Your white noise signal is just as real as my flying pig.

"Your" pig is as real as "your" definition. Cite a definition, from any authority other than you, that "my" white noise violates.

Actually, in the context of Hi-Fi reproduction, I've found it fine to leave the phase to fall where it may most of the time.

So a synthetic ideal impulse and "my" white noise differ ONLY in phase. I can hear a difference. Can you? I'm sure you can. Phase can be everything.

In a "Sound Science" forum, should it matter whether you think an omission that could be supported by NO textbooks is "right on"? Or should we stick with facts we can find in a reference?

 

[johncarm]

The definition of white noise has nothing to do with the question of whether phase needs to be considered in audio. Joe has made a rather extraordinary claim that phase is unimportant. Remember, my question is about the whole process of audio including equipment design and testing. Do you claim that all audio equipment design and testing can be carried out while ignoring phase?

 

[Joe Bloggs]

"Your" pig is as real as "your" definition. Cite a definition, from any authority other than you, that "my" white noise violates.

How about meeting any definition of just "noise" you care to choose from this page that also fits the umbrella definition in the first sentence?
https://en.wikipedia.org/wiki/Noise_(electronics)

"random fluctuation"

So a synthetic ideal impulse and "my" white noise differ ONLY in phase. I can hear a difference. Can you? I'm sure you can. Phase can be everything.

In a "Sound Science" forum, should it matter whether you think an omission that could be supported by NO textbooks is "right on"? Or should we stick with facts we can find in a reference?

Some texts discussing the audibility of phase distortions:

The piece on phase distortion was a refreshing change from the semi-science floating around our business. All things being equal, and if one has the option, of course get the phase correct - at least at the one point in space where it can be done!! However, this presents problems for two-eared listeners in multiple seats in reflective rooms (solve this one and a Nobel prize awaits). It is indeed fortunate that humans are so unresponsive to this effect because, if we could hear phase shift, we would go absolutely nuts in everyday life. Every time a reflected version of a sound adds to the direct sound, the phase shifts are enormous, and it happens in abundance in all rooms, even carrying on a conversation across a table. Do the stand up/ sit down test while speaking. The voice changes very subtly, but our hearing system compensates immediately and, on a scale of 10, the voice quality remains a 10. Yet the transfer function between the voice and the ears has greatly changed in both amplitude and phase. I cannot help but think of all the opera recordings and film voice overs that are done with librettos and scripts on large angled (sound reflecting) surfaces between the mouth and the mic. The signal is corrupted at the source! Thank your favorite diety for human adaptability.

Keep up the good work.

Floyd

Floyd E. Toole, PhD
Vice President Acoustical Engineering
Harman International Industries, Inc.

http://sound.westhost.com/ptd.htm#ref
http://www.audioholics.com/room-acoustics/human-hearing-phase-distortion-audibility-part-2

 

[johncarm]

How about meeting any definition of just "noise" you care to choose from this page that also fits the umbrella definition in the first sentence?
https://en.wikipedia.org/wiki/Noise_(electronics)

"random fluctuation"
Some texts discussing the audibility of phase distortions:
http://sound.westhost.com/ptd.htm#ref
http://www.audioholics.com/room-acoustics/human-hearing-phase-distortion-audibility-part-2

So is your claim that this information about the audibility of phase distortion means that no consideration of phase is necessary in designing and testing audio equipment?

 

[SoundAndMotion]

How about meeting any definition of just "noise" you care to choose from this page that also fits the umbrella definition in the first sentence?
https://en.wikipedia.org/wiki/Noise_(electronics)

"random fluctuation"
Some texts discussing the audibility of phase distortions:
http://sound.westhost.com/ptd.htm#ref
http://www.audioholics.com/room-acoustics/human-hearing-phase-distortion-audibility-part-2

Should we argue about what the meaning of "is" is? I'm not going to answer your decisions on parsing. Directly related to the use of "white noise" is this:

...the Wikipedia article on white noise is pretty clear for me. First sentence:
"In signal processing, white noise is a random signal with a constant power spectral density."

WRT the bold above: why do YOU keep bringing up phase distortion, when that is not the issue. It is a pure straw man in answering what I wrote. I have stated twice (this quoting make 3X):

My original point was "phase is important and cannot be ignored" when talking about the content of a signal. I make no claims about the role of phase distortion or audibility. I claim the description that the signal is completely described by the 2 values, amplitude and frequency, is false. Phase is required.

Does Toole disagree?

Quit deflecting.

 

[johncarm]

You guys have a right to post anything you want, but I wish we stay close to the subject of what knowledge is necessary to design and test audio equipment.

 

[SoundAndMotion]

You guys have a right to post anything you want, but I wish we stay close to the subject of what knowledge is necessary to design and test audio equipment.

Yes, although IMO my first post was relevant, I have contributed to derailing your thread (wrt the "white noise" stuff). Apologies.

 

[sonitus mirus]

Yes, although IMO my first post was relevant, I have contributed to derailing your thread (wrt the "white noise" stuff). Apologies.

 
Are you some sort of perception expert?  A professor, or maybe just a leader in some circle or group with a fundamental interest in perception?  I only ask, because there have been nearly a half-dozen similar threads all eventually coming around to some issue about perception with audio.  If I had to guess, it would appear that there is some perverse curriculum in a school course to invade this particular forum to argue this topic.  It almost always begins in a similar way, and migrates to audio perception.  You sweep into every single one of these discussions as the master that has to control the situation that your disciple has gotten themselves into.   Would you be honest enough to reveal any truth to my claims?

 

[reginalb]

Should we argue about what the meaning of "is" is? I'm not going to answer your decisions on parsing. Directly related to the use of "white noise" is this:
WRT the bold above: why do YOU keep bringing up phase distortion, when that is not the issue. It is a pure straw man in answering what I wrote. I have stated twice (this quoting make 3X):
Does Toole disagree?

Quit deflecting.

He wasn't answering you when he brought up phase distortion. And you seem extremely confused by the definition of the word "random."

 

[SoundAndMotion]

He wasn't answering you when he brought up phase distortion. And you seem extremely confused by the definition of the word "random."

My mistake: when he quotes me and then mentions "phase distortion" in his response to me, I just assumed he was answering me. To avoid confusion, he should quote the person he's responding to, not me. I think perhaps you are confused about the word "answering".

I don't think the definition of "random" is relevant in this thread, but I strongly doubt your definition is different than mine. Or perhaps you are confused? Does it matter here anyway? Get a dictionary, and I stand by everything I wrote.