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I'd rather this article was not merged with Audio quality measurements as I started the latter, and it's associated series, after looking at this one an deciding that it was beyond hope! I say that because it muddles ideas of system measurements with quality measurement and goes on to say that measurements do not measure quality!
While I agree that listening is always important, I and many others regard audio quality measurement to be about exactly that. If it doesn't work, then that's because you are making measurements that were not designed to measure audio quality as subjectively perceived. I believe that professionals in the UK and Europe had this sorted out decades ago, with the development of weighting curves based on subjective experiments, but that the US has yet to realise this. I'm quite happy to discuss things, and to work to improve this article, but until I have time to do that I'd appreciate it if the intentions of the one I started (to give a proper UK/European professional understanding of the term) were understood and preserved there. I know that many of the things said in this article are commonly stated ideas, but since they are easily shown to be wrong, they would be better stated perhaps on a page entitled 'common audio misconceptions' (with explanations as to why they are so), which I have considered starting -- Lindosland 00:59, 21 March 2006 (UTC)
I have put up merge banners. This does not look like it will be a difficult merge. I see no justification for separate articles in the content of the articles. Only justification is on the talk pages. -- Kvng ( talk) 14:23, 15 October 2010 (UTC)
Hi, this article has still not been merged. At this point, the content of this article is so far behind that of Audio system measurements it would probably be quite easy to merge. IF no one objects, I will do this eventually. Michaelgaccount ( talk) 04:44, 27 June 2012 (UTC)
As an example I will take this, which at first site is a correction of a commonly abused measurement. Yes, PMPO is nonsense, never defined anywhere, and number one hated term to be erased from a million advertisements (which seem to take power and multiply by a factor chosen at whim). RMS power though is also wrong, since without a definition of the test waveform and the averaging period (root MEAN square) it has no single meaning. Power in a steady state system is indeed calculated as rms, but its the VOLTAGE that is squared, averaged, and rooted, not the power! There have been many articles pointing out this simple error, and also pointing out that if you actually take a 1w (sinewave power) amplifier and calculate the RMS of the power over the cycle, the answer is not 1w but something a bit bigger! The correct term (almost never used) is 'max sinewave power'. Driven with a squarewave, a 1w amplifier will give 2w (of actual 'true' power!) out, which serves to make the point that its the waveform that we must specify, by convention, and nothing to do with rms, or even 'true' power. -- Lindosland 01:10, 21 March 2006 (UTC)
Following on from my above comments, and my emphasis on proper techniques, I would point out that it has recently become possible to make sophisticated measurements on a total system, including CODECs like MP3 based on real-time computer emulation of the human hearing process as we now understand it, including temporal and frequency masking, level-dependant frequency response, in line with the equal-loudness contours and proper combination of hair-cell responses across the band. These give good agreement with subjective assessments. Things have come a long way since basic engineering measurements were deemed not to give meaningful results, and this article should make that clear, rather than perpetuating the wrong idea that basic measurements are the same as quality measurements. I'll try to look up material in the recent AES papers. -- Lindosland 01:46, 21 March 2006 (UTC)
I believe that 'Audio system measurements' should not be merged with 'Audio quality measurments', simply because audio QUALITY can be measured or studied without an 'audio SYSTEM' involved (assuming that an 'audio system' is usually considered a combination of electronic and electro-mechanic devices, or at least a part of such a combination). A new, more general article 'Audio measurements' comprising both of the above articles would make sense, though.
Hi Omegatron. I see you have challenged the accuracy of the page I created on Distortion measurement, but you have not justified this on the talk page. I am all too aware that what I have written there is not generally understood, especially in the USA, but it is widely agreed, especially by professionals. I am in an unusual position here, because I have spent 25 years promoting 'proper' measurements, and am to some extent considered an authority on the subject. I could for example cite the prestigious 'The Audio Engineers Reference Book' by Butterworth Heineman, but then I wrote the chapter on audio measurement in it at the request of its editor, so is it fair to do that or not?! Tell me what you consider innacurate or wrong, and I am happy to discuss things (on Talk:Distortion measurement). -- Lindosland 12:15, 29 March 2006 (UTC)
After re-reading I realised that this article was much more POV than I had realised, and remembered that I had written it for the Lindos website and had not gone through it sufficiently after transferring it. I've now had a major attempt at Wikifying and have removed the template. It inevitably retains what might be perceived as some bias, but then it is intended to balance the existing article at Audio system measurements. I've left the other template, pending discussion. -- Lindosland 13:01, 29 March 2006 (UTC)
and I have been involved in discussions where evidence was given to me of the desirability of separating out viewpoints - so long as it is made clear than they represent only one viewpoint.
We are not talking of editor POV here, but the existence of alternative 'schools of thought'.
but I was simply pointing out that I can give references that are regarded as authoritative but which I wrote myself!
There is no dispute among those truly involved in the subject, just resistance from manufacturers who want big numbers for their marketing folk.
Audio is full of quacks selling 'snake oil' (like oxygen-free speaker cables)!
RMS power, a purely mathematical concept that should be banished!
Digital system tend not to - in general they generate 'hash' that is at no particular frequency,
These 'Lindos preferred measurements' happen to be to the International and European standards (as quoted all over the place in the articles). It is a fact that such standards are not widely understood or adhered to in the US. Lindos has agents in most of the world, but withdrew it's full time representative from the US because of this problem. He felt he was wasting his time in the face of ignorance. The US is well acknowledged as having been 'isolationist' in buying little from abroad until recently. Trying to mix European and US methods in this field is like trying to mix Islam and Christianity on one page - it isn't to be attempted. Most Wikipedians are, I suspect in the US. I therefore ask you all to think carefully about this before undoing my work.
I can be fairly confident is saying that most of the world's broadcast networks are routinely tested for quality using equipment designed by me (mostly the LA100). This includes the BBC (several million pounds worth) BT (ditto) BSB Sky, Independant Radio (ditto) and TV throughout the UK, plus the major broadcasters in France, Germany, Australia, South Africa, Japan, and so on, but not in the US! The BBC does all its automated testing across its entire radio network regularly using the Lindos LA100's. A few years ago I was invited by the editor of 'The Audio Engineer's Reference Book' (pub. by Focal Press), to write the section on Measurement. The introduction refers to "articles all written by world experts". I have been invited to give lectures to BBC and other organisations. Training schemes were set up in the BBC to train all engineers in the use of the LA100 and Lindos was paid to provide the on-site training. Lindos were contracted to design and make special test equipment for use in the BBC, the IBA, and other broadcast organisations. "Clearly biased" and "products that measure his way". Sorry but you've just got no idea! You may think that the AP systems set the standard. Excellent though they are for measuring to low levels (we have one), in most of the world, most of the time, they don't. And Lindos was around long before them, or Neutrik. Up until now I have tried not to shout about my role in audio measurement, but I think now I have no choice but to point out that I am proud to have had a major influence on the field. -- Lindosland 23:15, 4 April 2006 (UTC)
He felt he was wasting his time in the face of ignorance.
I thought it a good idea to write a new intro which makes clear the real distinction between subjectively valid quality measurements and basic measurements. Also a section explaining why they differ. Hope this meets with approval. I would still suggest keeping the other set of articles as they do go into much more detail that would be appropriate here. Note that there is an article on A-weighting plus a set on Equal loudness contours which I did a lot of work on, to balance the other one on ITU-R 468, and that all give a history together with benefits and weaknesses. This seems quite fair to me, and allows users to follow the whole story through in detail if they wish to. -- Lindosland 17:56, 5 April 2006 (UTC)
A recent edit by User:Howard Doctor replaced "Reducing cone excursion" with "Reducing a driver's bandwidth" as a method for reducing Intermod distortion (IMD). I hold that both are valid methods. I'm reworking the paragraph to include them both. Binksternet ( talk) 15:39, 1 October 2008 (UTC)
I made some changes to the section on frequency response. The first thing I did was to write a short description of what the frequency response measurement means. The next thing I did was to remove some stuff about what happens if the frequency response is not flat. Below I've highlighted the text I felt needed changing:
The signal should be passed at least over the audible range (usually quoted as 20 Hz to 20 kHz) with no significant peaks or dips. The human ear can discern differences in level of about 3 dB in some frequency ranges, so peaks and troughs must be less than this. Much modern equipment is capable of less than ±1 dB variation over the entire audible frequency range. Rapid variations over a small frequency range (ripple), or very steep rolloffs are considered undesirable as they can correspond to resonances associated with energy storage which produce delayed echoes and hence colouration, or decreased quality, of the sound.
Research by Toole [5] has shown that changes in frequency response much smaller than 3 dB may be audible. His work focused on unwanted resonances in loudspeakers. He showed that a resonance with a quality factor = 1 and amplitude of 0.3 dB may audible on some signals. His work has also shown that resonances with a high Q (i.e., a resonance with a small bandwidth and relatively large amplitude) are often less audible than resonances with a low Q (i.e., a resonance with a large bandwidth and relatively low amplitude) [2 refs]. The revision above seems to imply the opposite, that rapid variations in frequency response (high Q) are less desirable (more audible) than smaller variations in frequency response (low Q).
I decided not to summarise Toole's work in the article. I thought that it was too specialised in this context.
I've made some revisions to this section. What I've tried to do is improve the article by rewriting the section and adding references.
I've added references to articles in Audio Critic and Stereophile magazine. Audio Critic and Stereophile represent two different viewpoints on the usefulness of objective audio measurements. I've also referred to the work of Dr Floyd Toole. His work is relevant because he has linked objective measurements to the results of listening tests. Dr Toole used double-blind tests in his research. To try and maintain NPV, I've mentioned that there are other people who prefer to use non-blind listening tests (Stereophile magazine). Enescot ( talk) 22:45, 4 May 2009 (UTC)
The question of what should go here and what elsewhere interests me. I don't think the coverage of the subject is quite right yet here, so may I suggest it aims to:
Damping is only a factor as long as the signal is in phase with the electromotive force, which it rarely is. The damping effect is negligible already at two octaves above the resonant frequency.
Damping factor became a buzzword in the early days of solid-state amplifiers because it was something that tube amplifiers did "bad."
If damping factor was relevant for amplifiers, then transconductance (current) amplifiers should be really, really bad. They are not.
Damping factor is marketing. It is at home with Stereophile and the other audiophools. You know, the "golden ears" who claim they can hear the "sonic characteristics" of different metals (usually copper, silver and gold) in connectors and switches. Silver is usually said to sound hard or cold, and gold warm. Whereas copper sounds neutral. True story. — Preceding unsigned comment added by 89.253.73.146 ( talk) 22:13, 14 January 2014 (UTC)
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![]() | The contents of the Audio quality measurement page were merged into Audio system measurements. For the contribution history and old versions of the redirected page, please see its history; for the discussion at that location, see its talk page. (2012-07-01) |
I'd rather this article was not merged with Audio quality measurements as I started the latter, and it's associated series, after looking at this one an deciding that it was beyond hope! I say that because it muddles ideas of system measurements with quality measurement and goes on to say that measurements do not measure quality!
While I agree that listening is always important, I and many others regard audio quality measurement to be about exactly that. If it doesn't work, then that's because you are making measurements that were not designed to measure audio quality as subjectively perceived. I believe that professionals in the UK and Europe had this sorted out decades ago, with the development of weighting curves based on subjective experiments, but that the US has yet to realise this. I'm quite happy to discuss things, and to work to improve this article, but until I have time to do that I'd appreciate it if the intentions of the one I started (to give a proper UK/European professional understanding of the term) were understood and preserved there. I know that many of the things said in this article are commonly stated ideas, but since they are easily shown to be wrong, they would be better stated perhaps on a page entitled 'common audio misconceptions' (with explanations as to why they are so), which I have considered starting -- Lindosland 00:59, 21 March 2006 (UTC)
I have put up merge banners. This does not look like it will be a difficult merge. I see no justification for separate articles in the content of the articles. Only justification is on the talk pages. -- Kvng ( talk) 14:23, 15 October 2010 (UTC)
Hi, this article has still not been merged. At this point, the content of this article is so far behind that of Audio system measurements it would probably be quite easy to merge. IF no one objects, I will do this eventually. Michaelgaccount ( talk) 04:44, 27 June 2012 (UTC)
As an example I will take this, which at first site is a correction of a commonly abused measurement. Yes, PMPO is nonsense, never defined anywhere, and number one hated term to be erased from a million advertisements (which seem to take power and multiply by a factor chosen at whim). RMS power though is also wrong, since without a definition of the test waveform and the averaging period (root MEAN square) it has no single meaning. Power in a steady state system is indeed calculated as rms, but its the VOLTAGE that is squared, averaged, and rooted, not the power! There have been many articles pointing out this simple error, and also pointing out that if you actually take a 1w (sinewave power) amplifier and calculate the RMS of the power over the cycle, the answer is not 1w but something a bit bigger! The correct term (almost never used) is 'max sinewave power'. Driven with a squarewave, a 1w amplifier will give 2w (of actual 'true' power!) out, which serves to make the point that its the waveform that we must specify, by convention, and nothing to do with rms, or even 'true' power. -- Lindosland 01:10, 21 March 2006 (UTC)
Following on from my above comments, and my emphasis on proper techniques, I would point out that it has recently become possible to make sophisticated measurements on a total system, including CODECs like MP3 based on real-time computer emulation of the human hearing process as we now understand it, including temporal and frequency masking, level-dependant frequency response, in line with the equal-loudness contours and proper combination of hair-cell responses across the band. These give good agreement with subjective assessments. Things have come a long way since basic engineering measurements were deemed not to give meaningful results, and this article should make that clear, rather than perpetuating the wrong idea that basic measurements are the same as quality measurements. I'll try to look up material in the recent AES papers. -- Lindosland 01:46, 21 March 2006 (UTC)
I believe that 'Audio system measurements' should not be merged with 'Audio quality measurments', simply because audio QUALITY can be measured or studied without an 'audio SYSTEM' involved (assuming that an 'audio system' is usually considered a combination of electronic and electro-mechanic devices, or at least a part of such a combination). A new, more general article 'Audio measurements' comprising both of the above articles would make sense, though.
Hi Omegatron. I see you have challenged the accuracy of the page I created on Distortion measurement, but you have not justified this on the talk page. I am all too aware that what I have written there is not generally understood, especially in the USA, but it is widely agreed, especially by professionals. I am in an unusual position here, because I have spent 25 years promoting 'proper' measurements, and am to some extent considered an authority on the subject. I could for example cite the prestigious 'The Audio Engineers Reference Book' by Butterworth Heineman, but then I wrote the chapter on audio measurement in it at the request of its editor, so is it fair to do that or not?! Tell me what you consider innacurate or wrong, and I am happy to discuss things (on Talk:Distortion measurement). -- Lindosland 12:15, 29 March 2006 (UTC)
After re-reading I realised that this article was much more POV than I had realised, and remembered that I had written it for the Lindos website and had not gone through it sufficiently after transferring it. I've now had a major attempt at Wikifying and have removed the template. It inevitably retains what might be perceived as some bias, but then it is intended to balance the existing article at Audio system measurements. I've left the other template, pending discussion. -- Lindosland 13:01, 29 March 2006 (UTC)
and I have been involved in discussions where evidence was given to me of the desirability of separating out viewpoints - so long as it is made clear than they represent only one viewpoint.
We are not talking of editor POV here, but the existence of alternative 'schools of thought'.
but I was simply pointing out that I can give references that are regarded as authoritative but which I wrote myself!
There is no dispute among those truly involved in the subject, just resistance from manufacturers who want big numbers for their marketing folk.
Audio is full of quacks selling 'snake oil' (like oxygen-free speaker cables)!
RMS power, a purely mathematical concept that should be banished!
Digital system tend not to - in general they generate 'hash' that is at no particular frequency,
These 'Lindos preferred measurements' happen to be to the International and European standards (as quoted all over the place in the articles). It is a fact that such standards are not widely understood or adhered to in the US. Lindos has agents in most of the world, but withdrew it's full time representative from the US because of this problem. He felt he was wasting his time in the face of ignorance. The US is well acknowledged as having been 'isolationist' in buying little from abroad until recently. Trying to mix European and US methods in this field is like trying to mix Islam and Christianity on one page - it isn't to be attempted. Most Wikipedians are, I suspect in the US. I therefore ask you all to think carefully about this before undoing my work.
I can be fairly confident is saying that most of the world's broadcast networks are routinely tested for quality using equipment designed by me (mostly the LA100). This includes the BBC (several million pounds worth) BT (ditto) BSB Sky, Independant Radio (ditto) and TV throughout the UK, plus the major broadcasters in France, Germany, Australia, South Africa, Japan, and so on, but not in the US! The BBC does all its automated testing across its entire radio network regularly using the Lindos LA100's. A few years ago I was invited by the editor of 'The Audio Engineer's Reference Book' (pub. by Focal Press), to write the section on Measurement. The introduction refers to "articles all written by world experts". I have been invited to give lectures to BBC and other organisations. Training schemes were set up in the BBC to train all engineers in the use of the LA100 and Lindos was paid to provide the on-site training. Lindos were contracted to design and make special test equipment for use in the BBC, the IBA, and other broadcast organisations. "Clearly biased" and "products that measure his way". Sorry but you've just got no idea! You may think that the AP systems set the standard. Excellent though they are for measuring to low levels (we have one), in most of the world, most of the time, they don't. And Lindos was around long before them, or Neutrik. Up until now I have tried not to shout about my role in audio measurement, but I think now I have no choice but to point out that I am proud to have had a major influence on the field. -- Lindosland 23:15, 4 April 2006 (UTC)
He felt he was wasting his time in the face of ignorance.
I thought it a good idea to write a new intro which makes clear the real distinction between subjectively valid quality measurements and basic measurements. Also a section explaining why they differ. Hope this meets with approval. I would still suggest keeping the other set of articles as they do go into much more detail that would be appropriate here. Note that there is an article on A-weighting plus a set on Equal loudness contours which I did a lot of work on, to balance the other one on ITU-R 468, and that all give a history together with benefits and weaknesses. This seems quite fair to me, and allows users to follow the whole story through in detail if they wish to. -- Lindosland 17:56, 5 April 2006 (UTC)
A recent edit by User:Howard Doctor replaced "Reducing cone excursion" with "Reducing a driver's bandwidth" as a method for reducing Intermod distortion (IMD). I hold that both are valid methods. I'm reworking the paragraph to include them both. Binksternet ( talk) 15:39, 1 October 2008 (UTC)
I made some changes to the section on frequency response. The first thing I did was to write a short description of what the frequency response measurement means. The next thing I did was to remove some stuff about what happens if the frequency response is not flat. Below I've highlighted the text I felt needed changing:
The signal should be passed at least over the audible range (usually quoted as 20 Hz to 20 kHz) with no significant peaks or dips. The human ear can discern differences in level of about 3 dB in some frequency ranges, so peaks and troughs must be less than this. Much modern equipment is capable of less than ±1 dB variation over the entire audible frequency range. Rapid variations over a small frequency range (ripple), or very steep rolloffs are considered undesirable as they can correspond to resonances associated with energy storage which produce delayed echoes and hence colouration, or decreased quality, of the sound.
Research by Toole [5] has shown that changes in frequency response much smaller than 3 dB may be audible. His work focused on unwanted resonances in loudspeakers. He showed that a resonance with a quality factor = 1 and amplitude of 0.3 dB may audible on some signals. His work has also shown that resonances with a high Q (i.e., a resonance with a small bandwidth and relatively large amplitude) are often less audible than resonances with a low Q (i.e., a resonance with a large bandwidth and relatively low amplitude) [2 refs]. The revision above seems to imply the opposite, that rapid variations in frequency response (high Q) are less desirable (more audible) than smaller variations in frequency response (low Q).
I decided not to summarise Toole's work in the article. I thought that it was too specialised in this context.
I've made some revisions to this section. What I've tried to do is improve the article by rewriting the section and adding references.
I've added references to articles in Audio Critic and Stereophile magazine. Audio Critic and Stereophile represent two different viewpoints on the usefulness of objective audio measurements. I've also referred to the work of Dr Floyd Toole. His work is relevant because he has linked objective measurements to the results of listening tests. Dr Toole used double-blind tests in his research. To try and maintain NPV, I've mentioned that there are other people who prefer to use non-blind listening tests (Stereophile magazine). Enescot ( talk) 22:45, 4 May 2009 (UTC)
The question of what should go here and what elsewhere interests me. I don't think the coverage of the subject is quite right yet here, so may I suggest it aims to:
Damping is only a factor as long as the signal is in phase with the electromotive force, which it rarely is. The damping effect is negligible already at two octaves above the resonant frequency.
Damping factor became a buzzword in the early days of solid-state amplifiers because it was something that tube amplifiers did "bad."
If damping factor was relevant for amplifiers, then transconductance (current) amplifiers should be really, really bad. They are not.
Damping factor is marketing. It is at home with Stereophile and the other audiophools. You know, the "golden ears" who claim they can hear the "sonic characteristics" of different metals (usually copper, silver and gold) in connectors and switches. Silver is usually said to sound hard or cold, and gold warm. Whereas copper sounds neutral. True story. — Preceding unsigned comment added by 89.253.73.146 ( talk) 22:13, 14 January 2014 (UTC)
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