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The Effects of Small Changes over a Frequency Range and Big Changes over a Frequency - Page 3

post #31 of 48
Thread Starter 
Quote:
Originally Posted by anetode View Post

 

By whom?



Well, last time I said this, I got chewed out by about 4-5 members on this site...  Each of which said any of the following:

  • It's like raising the volume 1 dB...  No differences
  • Take this test that raises a frequency 1 dB...  No differences, you end up guessing
  • It's not audible...  (then they called me something that is the equivilent of idiot like it was something I should have known already)

Edited by tinyman392 - 1/15/12 at 8:23am
post #32 of 48
Quote:
Originally Posted by hulawafu77 View Post

even the slightest shift in change in placement can have a dramatic change in measurements.  How do you know for example, that the headphone was placed for measurement on his tests EXACTLY where it was before for his break in tests?  You don't.  And be very surprised if he does. 


 

For these particular tests, I believe he did not move the headphones off the test head for the duration. 

post #33 of 48

This is a very deep subject, and my upcoming Audio Book has an entire section on this. The short version is:

 

* Small changes in level (EQ) are more audible at midrange frequencies than at very low and very high frequencies.

 

* Low-Q boost and cuts (wide bandwidth) are more audible than high-Q boost and cuts.

 

* For any EQ change to be audible, those frequencies must be present in the source. This may seem obvious, but very narrow changes might miss some frequencies depending on the key of the music.

 

* I know this is a headphones forum, but when listening in a room, having absorption at all of the early reflection points makes it much easier to hear small changes in EQ. Not only EQ, but also small changes in reverb and panning, which applies more for mixing engineers than for hi-fi listeners. In a well-treated room anyone can reliably hear level changes as small as 0.5 dB.

 

--Ethan
 

Quote:
Originally Posted by tinyman392 View Post

OK, up until now, it has been widely believed that a 1 dB change could not be heard, and the test to this pointing users to test it themselves by increasing the entire amplitude of a sound by 1 dB…  That data then goes on to FR graphs where we are widely made to believe that these same changes will make no audible change…

 

post #34 of 48
Thread Starter 
Quote:
Originally Posted by hulawafu77 View Post

I wouldn't use Tyll's graphs as source.  If you understand how sound works, even the slightest shift in change in placement can have a dramatic change in measurements.  How do you know for example, that the headphone was placed for measurement on his tests EXACTLY where it was before for his break in tests?  You don't.  And be very surprised if he does.  There is a youtube video about audio myths that demonstrates very clearly how much change can be heard and measured from the slightest shift in placement.

 

And as much fun as measurements are, I think for hearing changes in 1db or headphone break-in, it's much more interesting if say Tyll did ABX testing.  That can be repeated, and verified with MANY trials if he can even hear the difference between a headphone with 10 hours of burn-in and 200 hours of burn-in.  Same for hearing changes of 1db.

Headphones remained on for each section of the tests involved.  In other words, between each section (when I switched EQs), I did take a break ever 2-3 EQ switches.  But for the duration of each section, the headphones remained in the same position.

 

The only reason why I included the use of Tyll's graphs was because it was stated that the 2-3 dB spikes in the treble along with the 1 dB increase in the mids weren't audible.  I just wanted to see if there was a difference between the two.  I know for a fact that I would not be able to hear these changes over the course of 300 hours though. 
 

 



Quote:
Originally Posted by EthanWiner View Post

This is a very deep subject, and my upcoming Audio Book has an entire section on this. The short version is:

 

* Small changes in level (EQ) are more audible at midrange frequencies than at very low and very high frequencies.

 

* Low-Q boost and cuts (wide bandwidth) are more audible than high-Q boost and cuts.

 

* For any EQ change to be audible, those frequencies must be present in the source. This may seem obvious, but very narrow changes might miss some frequencies depending on the key of the music.

 

* I know this is a headphones forum, but when listening in a room, having absorption at all of the early reflection points makes it much easier to hear small changes in EQ. Not only EQ, but also small changes in reverb and panning, which applies more for mixing engineers than for hi-fi listeners. In a well-treated room anyone can reliably hear level changes as small as 0.5 dB.

 

--Ethan
 

 



Thanks for this info :)  I definitely did notice that the mid-range EQs were much more noticable (maybe because most of the music I listen to are heavy with midrange).



Quote:
Originally Posted by hulawafu77 View Post

And what audio equipment do you use for music listening Ethan?  Just curious, what headphones, DAC/Amp etc you use.  Being a widely respected audio myth debunker.

 

Thanks.


No amps were used, everything driven straight from my iPod Touch 4G running EQu.

 

post #35 of 48
Thread Starter 
Quote:
Originally Posted by hulawafu77 View Post

Huh, you are EthanWiner too tinyman392?  :D



I'm confused a bit...  I'm not EthanWiner, actually, my name isn't even Ethan :p  Just because I agree with someone does make me him :D

post #36 of 48

The current version of EQu still gets levels wrong, at least on an iPhone 4S or an iPad. If it says it's boosting by 3 dB it's really boosting by 6 dB. Measure the output if if you want to verify this. That 1 dB reading on your iPod may very well be 2 dB. Probably the developer is using 10log for level calculations, instead of 20log, which is what it should be when it comes to voltage gain. EQu's output also isn't very clean--put a 1 kHz tone through a spectrum analyzer and you'll see two sidebands +/- 85 Hz from the main tone, ~50 dB down. The Equalizer app doesn't have these artifacts, and it doesn't get the dB levels wrong either. You may have to redo the experiments.

post #37 of 48
Thread Starter 
Quote:
Originally Posted by yuriv View Post

The current version of EQu still gets levels wrong, at least on an iPhone 4S or an iPad. If it says it's boosting by 3 dB it's really boosting by 6 dB. Measure the output if if you want to verify this. That 1 dB reading on your iPod may very well be 2 dB. Probably the developer is using 10log for level calculations, instead of 20log, which is what it should be when it comes to voltage gain. EQu's output also isn't very clean--put a 1 kHz tone through a spectrum analyzer and you'll see two sidebands +/- 85 Hz from the main tone, ~50 dB down. The Equalizer app doesn't have these artifacts, and it doesn't get the dB levels wrong either. You may have to redo the experiments.




I think you have the apps switched...  I did a review of both of these apps (I'm an app and headphone reviewer for another forum) a while back.  When you are describing EQu, it sounds like my description for Equalizer, and when you describe Equalizer it sounds like my description of EQu.  Equalizer was the equalizer that boosted much higher than EQu did.  Again, this is based on the review of both I did.  Also to add, Equalizer added much more distortion at a lower EQ compared to EQu.  I think you have these two apps switched; I've used both, and extensively compared both of them (further than just audio).


Edited by tinyman392 - 1/15/12 at 12:03pm
post #38 of 48
Thread Starter 
Quote:
Originally Posted by hulawafu77 View Post

I asked Ethan what musical equipment he used, you quoted me with a reply.  It was just a joke, I understood you may not have seen the question was directed at Ethan.
 



 

 

Oh, OK, makes more sense :)
 

 

post #39 of 48
Quote:
Originally Posted by tinyman392 View Post

I think you have the apps switched...  I did a review of both of these apps (I'm an app and headphone reviewer for another forum) a while back.  When you are describing EQu, it sounds like my description for Equalizer, and when you describe Equalizer it sounds like my description of EQu.  Equalizer was the equalizer that boosted much higher than EQu did.  Again, this is based on the review of both I did.  Also to add, Equalizer added much more distortion at a lower EQ compared to EQu.  I think you have these two apps switched; I've used both, and extensively compared both of them (further than just audio).


Nope, no mistake. I tried it again. EQu gets the levels wrong and it has the artifacts. Equalizer (the one with 7 parametric EQs) gets it right and has clean output as long as you avoid clipping. So please verify with measurements, or the results of your experiment cannot be trusted. Try it with a pure tone and measure the level (with a voltmeter if you want). Then try boosting that frequency by 3 dB. When I try it, the voltage doubled--a 6 dB increase. If you have a spectrum analyzer (software and a sound card will do), you might see the artifacts surrounding the main tone. This, however, won't affect your experiment because the sidebands are still there even if you leave EQu flat.

 

I got both apps for the iPad in December 2010. It's been almost a year since I last did the test, and today, EQu still behaves the same way on an iPhone 4/4S, and an iPad.


 

 

post #40 of 48

 

Quote:
Originally Posted by tinyman392 View Post



Well, last time I said this, I got chewed out by about 4-5 members on this site...  Each of which said any of the following: [...]

 


 

Quote:
Originally Posted by tinyman392 View Post

 

The only reason why I included the use of Tyll's graphs was because it was stated that the 2-3 dB spikes in the treble along with the 1 dB increase in the mids weren't audible.  I just wanted to see if there was a difference between the two.  I know for a fact that I would not be able to hear these changes over the course of 300 hours though.

 


I see. The key here is that you have to separate a couple of things. First off, sub-1db differences can be noticed in an ABX test settings, the usual threshold quoted for making sure of volume matching is .1db (not that every change is audible down to a .1db difference, but that at that point the difference becomes negligible). With headphones, on the other hand, the situation is more complicated as even minor positioning changes of the fit can easily alter the response by 3db or even more! Even the cushions wearing in (and wearing out) can effect difference of a couple of db because of the difference in the seal. This makes measuring headphones an annoyingly rigorous procedure (as I'm sure purrin or Tyll can attest to). I've seen two graphs of measurements from the same headphone which showed a huge suckout, like a 15db dip in response which disappeared after nudging the phones over a bit.

 

In connection to the burn-in differences of a couple of db that you mentioned I think it's important to maintain perspective. These differences could be measurement artifacts to begin with, not to mention the differences in fit and the batch differences, which are often greater than those that came up in the burn-in graphs. So it's simply that the measured differences may also be negligible, even though there's a decent change that someone could ABX the difference (which isn't possible, due to the minute differences in fit and the difficulty of convincing someone to wear a headphone for 300 hours straight without touching it for fear of invalidating the results). As such it is both premature and foolish to assume that those results substantiated any claims of burn-in, even though they were the product of a great effort.

 

As far as EQ, I think what you're doing is awesome. I know from personal experience that it takes a delicate touch to fix response deficiencies.

post #41 of 48

a old JAES paper gives the following just detectable difference thresholds - as you can see it is a function of how big and how wide both, as a function of frequency too

 

http://home.provide.net/~djcarlst/abx_crit.htm

 

 

abx_crit.gif

post #42 of 48
Quote:
Originally Posted by jcx View Post

a old JAES paper gives the following just detectable difference thresholds - as you can see it is a function of how big and how wide both, as a function of frequency too

 

http://home.provide.net/~djcarlst/abx_crit.htm

 

abx_crit.gif


That really depends on the testing conditions though, for example ABXing a pure sinewave of 440 Hz through EQ with a 1/24 th octave band centered at 440 Hz should be quite easy even if the amplitude of the said EQ is just 1 dB.

That become impossible (or very near impossible) with music or pink noise.

 

 

post #43 of 48
Thread Starter 
Quote:
Originally Posted by anetode View Post

 

 


 


I see. The key here is that you have to separate a couple of things. First off, sub-1db differences can be noticed in an ABX test settings, the usual threshold quoted for making sure of volume matching is .1db (not that every change is audible down to a .1db difference, but that at that point the difference becomes negligible). With headphones, on the other hand, the situation is more complicated as even minor positioning changes of the fit can easily alter the response by 3db or even more! Even the cushions wearing in (and wearing out) can effect difference of a couple of db because of the difference in the seal. This makes measuring headphones an annoyingly rigorous procedure (as I'm sure purrin or Tyll can attest to). I've seen two graphs of measurements from the same headphone which showed a huge suckout, like a 15db dip in response which disappeared after nudging the phones over a bit.

 

In connection to the burn-in differences of a couple of db that you mentioned I think it's important to maintain perspective. These differences could be measurement artifacts to begin with, not to mention the differences in fit and the batch differences, which are often greater than those that came up in the burn-in graphs. So it's simply that the measured differences may also be negligible, even though there's a decent change that someone could ABX the difference (which isn't possible, due to the minute differences in fit and the difficulty of convincing someone to wear a headphone for 300 hours straight without touching it for fear of invalidating the results). As such it is both premature and foolish to assume that those results substantiated any claims of burn-in, even though they were the product of a great effort.

 

As far as EQ, I think what you're doing is awesome. I know from personal experience that it takes a delicate touch to fix response deficiencies.


I 100% understand and do see what you're saying.  There are just too many variables to account for as of now.  I just wanted to put out that just because the changes were minute that they can be audible vs they aren't audible at all (something a lot of people have said constantly).  That was the only reasons to include it.  To add another reason why someone couldn't play 300 hours straight would be that they will undergo ear fatigue...  That will cut into results :p 

 

I just wanted to put it out there that some small changes (some as small as 1 dB), whether or not it appeals to burn in is arbitrary, are definitely audible and shouldn't be thrown out for the reason that they aren't audible.  What have I learned from this experience that I could take away in practical use?  If I hear a song where I don't notice an instrument as well, I can bump a certain frequency range 1 dB and not harm the rest of the spectrum too much :p 

 

 

 


Edited by tinyman392 - 1/15/12 at 10:01pm
post #44 of 48

We just need a quadriplegic volunteer...  wink.gif

post #45 of 48
Thread Starter 
Quote:
Originally Posted by BlackbeardBen View Post

We just need a quadriplegic volunteer...  wink.gif



LOL...  Naw, if he can headbang, then we'll run into problems tongue.gif

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