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an interesting question about headphones and frequency range..!

Discussion in 'Sound Science' started by plonter, Feb 18, 2009.
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  1. plonter
    Hi all. just interested in the next question:
    why are headphones made with a frequency response range that's above and beyond the human hearing capabilities? [​IMG] is there a difference between a 20-20 can and a 5-45 can (not talking about sound signatures diferences,capabilities only)?
    thx for your kind answers!
     
  2. Rempert
    I think you should not pay too much attention to some of these ridiculous frequency response specs with headphones.

    It gets tricky because different companies use different levels of tolerance to determine their frequency response specs. Sometimes this tolerance is listed, but often it is not. For example, my nearfield monitors are listed as 49 hz to 20 khz, +/-1.5 db. I have also some cheap old Logitech Z640 speakers, that were listed as 35 hz to 20 khz. Now there is no tolerance listed for those Z640, but I'd bet it is more like +/-10 db. Not a fair comparison, by any stretch.

    With headphones though, it gets even trickier, because the ideal frequency response isn't necessarily flat. There has to be compensation for the filtering your head and outer ear normally do to sounds which won't happen when the sound is pumping directly into your ear from headphones.
     
  3. apatN Contributor
    They don't really matter, no.
    I did hear a story though that even though you can't actually hear it, it is better. Oh yes, head-fi style. [​IMG]
     
  4. plonter
    so the denon's 5hz-45khz is not true? they are not really produce those frequencys?
     
  5. shubhangam
    from what I know,

    larger ranges can be better in the sense that <20 hz can be 'felt' so it gives some extra twang to the music.

    >20 khz is for something that the distortion shifts towards the right of the curve to make the sound better or something. don't quote me on that though.
     
  6. apatN Contributor
    Quote:

    Originally Posted by plonter /img/forum/go_quote.gif
    so the denon's 5hz-45khz is not true? they are not really produce those frequencys?



    They probably are but you are not able to actually hear them.
     
  7. ClieOS Contributor
    Rempert said it well, and I have a few points of my own to add. Here is a portion of my IEM guide regarding headphone frequency. It is meant for IEM user in portable setting, but same principles are true to all headphones.

    Quote:

    Originally Posted by ClieOS /img/forum/go_quote.gif
    In regard to IEMs' frequency response




     
  8. plonter
    an interesting post clieos..so is it all a lie? i mean..how can they do that?
    all the big companies like senn agk...it doesnt make sense to me.
    in fact..i really tought that headphones actually can produce those frequencies(in optimal situations and gear ofcourse)and we just can't hear them .
    and one more thing..if it is a marketing trick,than should they need to know better? i am talking of the headphones companies...i mean,they are obviously know that a long time audiophiles(and even not a long time) are aware of this "lie" (and yeah! it IS a lie if it is not true!)[​IMG] and still keep going with that?? that's what i don't get!
    and ofcourse there are some that actually measuring the headphones!
    thx!
     
  9. Shoewreck
    I'd assume that 5-35K is generally better than 20-20K. The tolerances are usually big (6-10dB). If 10dB falloff happens only far outside of your hearing range you may hope for quite even response within it.
    Just don't pay much attention to comparing different manufacturers top headphones ranges. They usually just add 500Hz to HF limit of a competitive product and draw it on their boxes. But if you compare ranges within HP's of a single manufacturer a wider range would honestly mean more extension.
     
  10. krmathis Contributor
    Its all about frequency fall-off (tolerance), I would say.
    The tolerance are often 6-10db, and a 'phone with a frequency range of 20Hz-20KHz would be -10db within the hearing range (ex. 19KHz and/or 25Hz. While a 'phone with a frequency range of 5Hz-35KHz might have the -10db drop outside our hearing range (ex. 30KHz and/or 10Hz)..
     
  11. Rempert
    It's not a lie. There are legit measurements involved. It's just that there is no real, useful standard of how much the frequency response can vary before we should start saying this headphone can't reproduce it. And also that 20hz-20khz is more than enough, but if you can claim better in a competitive market you've got to do it.

    I might draw a comparison to the "viewing angle" spec on flat screen monitors. You get the cheap monitor with a viewing angle of 170 degrees, and the super expensive one with a viewing angle of 178 degrees. There is some truth to these specs, but they are still totally absurd! Who is going to sit 89 degrees from perpendicular to a screen, and what could they possible hope to see at that angle?! And why does a screen with 170 degree viewing angle start to have the colors get darker if I move 40 degrees or so? It would be better if they had to use a much tighter, industry standard tolerance for how much the image can get lighter or darker, and give us some actually useful information about where the viewing angle is really accurate. But there is no such standard, and manufacturers understandably must use the highest number they can claim a legitimate measurement for in order to be competitive. Frequency response specs are the same kind of game.
     
  12. gregorio
    IEM Guide - Inaccuracies in the post quoted above:

    "Some of you might have read from else where that human, although can't hear sound beyond 20KHz, can still feel the present of ultrasound (and the harmonic distortion caused by ultrasound) and it does have a positive effect on SQ - This is true."

    No it's not true. There was some research carried out by a Japanese scientist many years ago which proved this. This research has been quoted many times in numerous publications and on the net. However, it was later shown that the methodolgy for the experiment was flawed and although the experiement has been recreated a number of times, no one has ever managed to obtain a significant result.

    "However, giving that almost all CD, lossy and lossless music produced these days have a cap on 20KHz in recording / encoding".

    All CD format audio requires a brickwall filter to remove all frequencies above 22,050Hz. It's a condition of digital audio that the audio frequency encoded can be no higher than half the sample rate (the Nyquist Point). So CD has a fixed sample rate of 44,100 samples per second which therefore equals an absolute maximum audio freq of 22,050Hz. Anything higher than this must be completely eradicated!

    "plus most sources only equip with a 16bits DAC that ain't capable of rendering sound beyond 20KHz efficiently".

    Not necessarily true. CD source material as mentioned above can theoretically go as high as 22.050 but other 16bit sources can encode frequencies more than double the CD limit. The maximum audio frequency which can be encoded is not related to bit depth but to sample rate. Bit depth encodes amplitude, sample rate encodes audio frequency.

    From about 60Hz down, the ears become increasingly inefficient and the body's ability to 'feel' sound gradually takes over. However, for the body to feel these low frequencies it requires that these frequencies hit the body, not just the ears. So cans which proclaim 5Hz freq response are, IMO, pretty much pointless, except from the fact that hopefully if they can reproduce 5Hz maybe they are reasonably accurate when it comes to frequencies which are useful.

    G
     
  13. plonter
    ok..thanks for the replies guys. so the greater the frequency range is (usually) than it's benefits the frequency that we can actually hear.
    am i right..?
    and one more question if i might...how do they measure this..? do they have certain equipment that give them the results? and do you think that the results are similar to those they publish?..!
     
  14. nick_charles Contributor
    Quote:

    Originally Posted by plonter /img/forum/go_quote.gif
    and one more question if i might...how do they measure this..?(1) do they have certain equipment that give them the results? and (2) do you think that the results are similar to those they publish?..!



    (1) If they do it seriously they use some kind of fake head with microphones in it to mimic a human listener .

    (2) Who knows ?
     
  15. gregorio
    Plonter "ok..thanks for the replies guys. so the greater the frequency range is (usually) than it's benefits the frequency that we can actually hear.
    am i right..? "

    No, there is no point in cans that can go up to 35kHz, humans can't hear that high and CDs contain absolutely no freqs above 22kHz.

    G
     
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