This might seem like a silly question, but the equal-loudness contours (originally the Fletcher-Munson curves), and now the ISO 226 standard, all basically show the actual SPL (dB) loudness of a frequency that sounds just as loud as another frequency. It also shows that this varies based on the actual listening volume. But WHO CARES? - is what I want to know.
I mean, it's been very well established that a perfectly flat SPL vs. frequency curve, measured in an anechoic chamber, is what sounds best to listeners. So when we would we care about these equal-loudness curves, or for that matter, when would we want to equalize to conform to one of them?
SG
I mean, it's been very well established that a perfectly flat SPL vs. frequency curve, measured in an anechoic chamber, is what sounds best to listeners. So when we would we care about these equal-loudness curves, or for that matter, when would we want to equalize to conform to one of them?
SG
smellygas said:
If the recording microphones received a 100db SPL concert and you want to listen at 72db in your home, a db_record vs. db_play calibrated ISO 226 loudness coutour circuit adds dynamics that makes the music sound much more realistic. If you sat in the back of a live performance where the SPL was 72db much of the dynamics would also be lost. You want the dynamics and frequency SPL balance of stage mics at normal home listening levels.
It would sound best to just play the recording at 100db SPL in a dedicated room, and this is great a few hours each week, but just not normal daily home life.
Hey, these are all very interesting replies. I was thinking along the same lines, but I wasn't 100% positive.
What kind of confuses me is why this guy:
http://web.mac.com/jon_whitledge/Whitledge_Designs/Audio_System_Publicity_files/CAE_part1_jun08.pdf
equalizes his system to follow the inverse of a B-weighted curve. (i.e. 24dB boost at 20Hz and 11dB boost at 20kHz). Is there any merit to this? He references a JAES article from 1992. If this is an optimal equalization, I guess I'll pay $5 for the article.
SG
What kind of confuses me is why this guy:
http://web.mac.com/jon_whitledge/Whitledge_Designs/Audio_System_Publicity_files/CAE_part1_jun08.pdf
equalizes his system to follow the inverse of a B-weighted curve. (i.e. 24dB boost at 20Hz and 11dB boost at 20kHz). Is there any merit to this? He references a JAES article from 1992. If this is an optimal equalization, I guess I'll pay $5 for the article.
SG
smellygas said:Hey, these are all very interesting replies. I was thinking along the same lines, but I wasn't 100% positive.
What kind of confuses me is why this guy:
http://web.mac.com/jon_whitledge/Whitledge_Designs/Audio_System_Publicity_files/CAE_part1_jun08.pdf
equalizes his system to follow the inverse of a B-weighted curve. (i.e. 24dB boost at 20Hz and 11dB boost at 20kHz). Is there any merit to this? He references a JAES article from 1992. If this is an optimal equalization, I guess I'll pay $5 for the article.
SG
This was a "competition grade" car audio system, built into a Dodge Sprinter van - does that relate to the application or environment most of us would be considering for a home system?
Re: Re: Equal-Loudness-Curves / Fletcher-Munson / ISO 226 / etc. - WHY do we care?
Atkinson has a good summary of the evidence here:
http://www.stereophile.com/features/103/index2.html
And another good paper is this one:
http://www.aes.org/e-lib/download.cfm?ID=5270&name=harman
You could probably qualify my statement further, but what the evidence does NOT say is to equalize against one of those standard U-shaped curves.
SG
sreten said:
Hi,
The above statement needs serious qualification to be accurate.
Atkinson has a good summary of the evidence here:
http://www.stereophile.com/features/103/index2.html
And another good paper is this one:
http://www.aes.org/e-lib/download.cfm?ID=5270&name=harman
You could probably qualify my statement further, but what the evidence does NOT say is to equalize against one of those standard U-shaped curves.
SG
Hi,
One would surmise that ISO 226 does not exist just to enable
you to do something not very clever with them, which you seem
to be implying.
Do they have much to do with loudspeaker design ?
Yes if you do something clever with them. Such as not designing
a speaker flat to 20Hz but with a max SPL level that is inaudible.
Who is choosing the evidence ? for what circumstances ?
/sreten.
One would surmise that ISO 226 does not exist just to enable
you to do something not very clever with them, which you seem
to be implying.
Do they have much to do with loudspeaker design ?
Yes if you do something clever with them. Such as not designing
a speaker flat to 20Hz but with a max SPL level that is inaudible.
Who is choosing the evidence ? for what circumstances ?
/sreten.sreten said:Hi,
One would surmise that ISO 226 does not exist just to enable
you to do something not very clever with them, which you seem
to be implying.
Do they have much to do with loudspeaker design ?
Yes if you do something clever with them. Such as not designing
a speaker flat to 20Hz but with a max SPL level that is inaudible.
Who is choosing the evidence ? for what circumstances ?
I'm sorry, but I read what you wrote twice, and I don't understand what you're trying to say.
SG
smellygas said:
Really, I don't think that is a proven fact at all.
I don't think the curves are all that accurate to base any science on. IMO It only shows a trend as where are ears are most sensitive and that some bass boost is needed lower listening levels.
Does it make sense that a speaker design with a similar response to the Fletcher-Munson curve would be the flattest sounding at the brain interface, ala BBC dip and all that.
As stated, they can be useful for gaining the original frequency response as recorded when played back at lower levels. They shouldn't be applied fully in all situations though as music will be mixed with them in-built as it were, the mixing engineer would have heard through his monitors and mixed to what sounded right, quite probably increasing the level of bass etc. (in considering pop/rock/dance music). Providing you play at the mixing level on equally flat speakers you should also achieve an optimum response
Re: Re: Equal-Loudness-Curves / Fletcher-Munson / ISO 226 / etc. - WHY do we care?
The curves are derived from numerous empirical studies of equal-loudness, then consolidated by a standards committee. The fact that there were multiple studies conducted by different, independent groups and they all produced similar results tells me that the curves are probably valid.
Furthermore, I don't think that a speaker design with a similar response to the F-M curve, measured anechoically, will sound the most pleasing. Please refer to the two links I provided which refer to actual studies that support the concept that anechoic flat is the most pleasing loudspeaker response.
SG
infinia said:
The curves are derived from numerous empirical studies of equal-loudness, then consolidated by a standards committee. The fact that there were multiple studies conducted by different, independent groups and they all produced similar results tells me that the curves are probably valid.
Furthermore, I don't think that a speaker design with a similar response to the F-M curve, measured anechoically, will sound the most pleasing. Please refer to the two links I provided which refer to actual studies that support the concept that anechoic flat is the most pleasing loudspeaker response.
SG
sreten said:One would surmise that ISO 226 does not exist just to enable
you to do something not very clever with them, which you seem
to be implying.
Do they have much to do with loudspeaker design ?
Yes if you do something clever with them. Such as not designing
a speaker flat to 20Hz but with a max SPL level that is inaudible.
Who is choosing the evidence ? for what circumstances ?
Following is my paraphrase / interpretation of the quote. Sorry if i dont get it 100%, since i am no native english speaker, as most of you are.
I think, that ISO 226 (the Equal Loudness Countour) has to be used in the right way, while you seem to be drawing the wrong conclusions from it.
Does ISO 226 have something to do with loudspeaker design?
Yes, but you have to use the information it holds in the right way. This way is, for example, to identify the lowest frequency, one can hear at a certain level. Then you design a loudspeaker with this information, so that it doesnt struggle to produce frequencies, which you wont hear anyway, since it cannot make them loud enough, by raising the low frequency corner of said speaker.
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