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Headphones fast and slow

Discussion in 'Sound Science' started by charlesc, Sep 13, 2014.
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  1. vid
    Not at all. Please do post a direct link to the study, or the name of the study, that you want to show me to prove your point. Also, as I said, if anyone hasn't yet seen the measurements I've posted of the relationship between freq response and decay (which I've posted in about ten different threads over the past year), ask me and they'll be given - but you haven't asked nor shown want, so hard to say I don't give proof. Neither has bigshot asked for them, which must mean he wants to dismiss it.
  2. ProtegeManiac Contributor
    Just a few notes on that experiment:
    1) It also depends on the quality of each driver. While it is true that frequency response isn't the only factor, the problem is that even if in theory a lighter diaphragm would be lighter, headphones of comparable quality aren't likely to have one with a heavy enough diaphragm to have a problem, and a lesser headphone would more likely have a problem with the toughness of its diaphragm than its mass.(ie it might break up too quickly). It's also possible that in one driver you might boost the bass, but its diaphragm while light isn't as structurally good as the others, so that one will start breaking up.
    2) There's also nominal impedance vs transient impedance. In some frequencies the impedance of a dynamic driver might shift, and in some cases, far enough.  If the amplifier will have trouble keeping up with these swings in one headphone then immediately it will sound different from the others, even if the resulting response is equalized, since you get the response graph using a simple test tone, not one with actual music where you have a lot of sounds at different levels happening at the same time.
    3) Equalization affects each transducer differently. Were all EQ'd graphs identical? Thing is you used a 27-band graphic EQ, not a complex multi-band parametric (not that even the latter can do that). Do all points on the graphic EQ correspond to the ideal center frequency for fixing peaks or dips in the response for all headphones? Even if you had Q-factor control, there is also a tendency for too narrow or too wide settings to actually make the equalization sound less natural.
    swspiers and cjl like this.
  3. bigshot
    Really, you need to make the effort to do legwork to find out for yourself. I've taken a day or two many times to chase down and figure out aspects of sound... not because I want to win a stupid forum pissing match, but because I want to know how to make my stereo sound better. I did that when I wanted to find out what jitter was, how to balance response, how to read the specs on amps... and the goal was understanding. Try that, it works.
    But to get you started, I'd suggest you watch Ethan Winer's two videos from the AES seminars and check out all the links in the Testing Audio Myths post at the top of this forum.
  4. castleofargh Contributor
    what I seem to remember was roly talking about 20ms as masking time, not 0.2s ^_^.  an understandable cause of mistake, but a significant one.
    and this graph doesn't at all show this to be wrong. 200hz looks to be around 0.06 or 0.07s so a good 3 times longer than what roly was talking about. making his statement a pretty safe one.
    looking at some waterfall graphs(I picked 5 at random on M.R.O), it seems like most headphones hardly ever reach 10ms in the high freqs(and I won't even start talking about the DB attenuation...). they do have longer decays in the low frequency very often, however, your graph and the entire PDF is making very clear that the threshold of audibility rises a lot more than the decay values I've been looking at on the waterfall plots.
    so what roly said did look legit, and the interesting pdf you provided(thanks for that) would make me think that big shot is right and that the decays of headphones seem to be below what matters.
    now it's somehow a generalization of the topic, and I'm sure a strong ringing at one precise frequency might not end up sounding like a wide spread decay. but to sound different they first need to be long enough and loud enough.
    can we all agree to this?
  5. Roly1650
    Thanks for that, saves me some trouble as I'm on my ipad, my banana fingers prevent me from cutting/pasting and responding to each individual poster. My conclusion was based on deductive reasoning from the Wiki I linked. The last word? Not my intention, just trying to stop the thread bogging, anybody who considers my posting as definitive is crazy! But the evidence suggests............

    I'm glad you understood the linked PDF, it confused the crap out of me, I know I'm thick but I can't understand why anybody would wear headphones to measure room decays, the setup and methodology was less than explicit imo, unless I missed something. There was also an awful lot of conditional ifs, maybes and perhapses and I found the conclusion anything but! I did get a couple of things from it, the first was that they concluded that music reproduction was far more tolerant than test signals, something that most testers concur with time after time in any number of different tests. Did they use music or test signals in this test, does anybody know, I couldn't find it. Secondly this: "Even with an initial stimulus level of 3 s, half the listeners could not hear the 32 Hz resonance in the 70 dB SPL signal". 3 seconds might as well be a lifetime in music reproduction, thats the equivalent of leaving home to catch a plane the same time it's due at the end of the runway for take-off! Surprisingly the 85 dB graph doesn't look all that much different. If I was a loudspeaker manufacturer I'd be jumping up and down with joy, I could make the cabinet out of any old junk, nobody could hear it....joke!

    And one final point, I don't think my preceding post indicated in anyway that I thought CSD plots were a waste of time, but I still don't think they have much merit alone, just like any other measurement in isolation and perhaps much more useful to a speaker designer, they have larger cabinet and panel dimensions to worry about than headphone designers. And sorry, I'm certainly not gonna wade through all those links.

    I agree, I think. I used to be indecisive, now I'm not so sure.
  6. vid
    I did the legwork - spent the last two or so years building up, testing, and improving a measurement setup, writing custom software for it, and taking what amounts to about a thousand measurements of headphones, mods, EQ, and indeed, the relationship of frequency response and decay.
    The result of the work is that I can ask you why you'd say decay can't be heard but changes to the freq response can, when I can show decay to change predictably with frequency response. Note that I've not said this proves decay to be audible - I've asked you to defend your view of decay by addressing the data that's going against it.
  7. bigshot
    How much decay? An audible amount? When I talk about headphones or speakers, all I am interested in is what I can hear. I don't look at measurements for the abstract joy of measurements themselves. I am looking to find a pair of cans that sounds better than another pair of cans. Frequency response is a significant issue in the way headphones sound. Decay is unimportant.
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