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If you put your two hands over two ears while listening to music .

  1. May 12, 2014 #1
    If you put your two hands over two ears while listening to music, sounds of which frequency range will be more audible?


    When I listen to music, I notice that if I put my two hands over my two ears, some sounds become more audible than others. Please check it yourself. I don't know terminology of music, so here is how I describe my listening experience. Some sounds, that sound mettalic ( probably cymbals? ) disappear, whereas some sounds with beats/ rhythm ( probably some drums, but could be other bass instruments, I don't know for sure ) become more audible/ enhanced. The reason I want to know this is because I like those sounds that are less audible if I don't put my hands over my ears. Another point is, I have noticed that, even if I don't put my hands over my ears while listening to music with an old 21" or 29" CRT TV ( that has one speaker on either side, and the TV channels I listen to probably transmit sounds in mono ), the sounds that are less audible ( those drums/ bass/ I don't know for sure sounds ) when I listen to them with my stereo sound system are always more audible/ enhanced.

    Please do a little experiment yourself by putting your two hands over your ears while listening to music. You'll probably do me the biggest favour in my life. ( For 6 years, I cannot listen to my favourite music, because when I listen to music with my stereo sound system, the sounds I like are always less audible, and that's why barely enjoyable. )
     
  2. jcsd
  3. May 13, 2014 #2
    Do you place your hands flat on your ears? I can hear fine - when I put hands on my ears flat, I can hear far less. If I put them on my ears in a bowl-like-shape, some frequencies get amplified and everything is transposed about half a tone down. Also happens when I'm yawning.
     
  4. May 13, 2014 #3
    Thank you very much for answering.

    Yes, what I do is put my hands midway between flat and bowl-shaped, so that my hands are slightly arched, but still touches the external ear lightly. Or, I sometimes press my tragus against the external auditory meatus ( the canal that leads to the eardrum ) with my index fingers, and that produces the same effect.
     
  5. May 13, 2014 #4
    I know the answer, but I have no evidence whatsoever to sustain it and it's against the rules to post suppositions. I need a peer reviewed paper to back up my answer. Also, why is this at this section of the forum?


    I have already done that. I've experimented as well with different ear plugs. That's why I say I know the answer.
     
  6. May 13, 2014 #5
    Because I think music is fun.
     
  7. May 14, 2014 #6
    Oh. :smile:

    I still can't find anything to back up my answer, but you pretty much have the answer already. Just look for the frequencies of drums/ bass/, etc. They are deep sounds, that's what becomes more available when you do that. Acute sounds become less audible. Now you just need to find the frequency of said sounds. :smile:

    If it helps you, percussion instruments will be heard clearly even with ear plugs because they produce vibrations throughout the entire body. Deep sounds make your body vibrate as well. It most certainly (I'm not sure, I need evidence) it's your bones the ones delivering those sounds when you put your hands over your ears.
     
  8. May 30, 2014 #7
    Sounds with low frequencies (or rather, low frequency ranges).

    I've done it :smile:.

    It's a pretty good description. They key thing here are the frequency ranges of sounds/instruments (and, physically, the wavelengths of the sounds). Check out this table:

    frequency-spectrum.jpe

    This table shows that the frequency range of cymbals lies above the frequency range of bass drums (kick drums) and toms. And also that the frequency range of guitars (standard 6-string) lies above the the frequency range of bass guitars (standard 4-string). Note that the table does not show that instruments also have different intensities for different frequencies (a bass drum has a lot of intensity in the frequency range 50-100 Hz (ca), and a crash cymbal has intensities in the frequency range 400-10 kHz (ca).

    Off the top of my head, I think the main reason to why low frequency sounds get more audible when you put your hands over your ears, is simply that your hands are "filtering" (absorbing, diffracting, reflecting) some of the higher frequency sounds. See e.g. diffraction.

    Technically speaking, you apply a sort of acoustic lowpass filter to the sounds (a lowpass filter lets low frequency sounds pass, and attenuates high frequency sounds).

    You can try this yourself with loudspeakers. A two-way speaker has got a bass element, "woofer", for bass and some midrange sounds, and a "tweeter" for higher frequency sounds. See Use of Multiple Drivers in Loudspeakers.

    Picture of a two-way loudspeaker:
    2way_speakers.jpg


    If you hold/place some cloth (e.g. blanket, towel or whatever) over the tweeter (but make sure you don't touch the membrane with the cloth, because this will change the sound), you will notice that high frequency sounds will be attenuated. If you do the same with the woofer (apply a cloth), you might notice some attenuation of midrange frequencies, but low frequency sounds (e.g. bass, bass drum) will still easily be heard more or less unchanged, regardless of the cloth. You should be able to do this with your hands instead of a cloth too. Try it, and hear what happens. See also Loudspeaker Sound Contours.

    Generally, low frequency sounds are more difficult to attenuate than high frequency sounds, see e.g. Soundproofing - Absorption.

    This "low pass filter" phenomenon can also be heard when you stand outside "closed" rehearsal rooms and music clubs - you will easily hear low frequency sounds (bass guitars/bass drums), while the higher frequencies (e.g. cymbals) will be greatly attenuated.

    If you don't like your audio system, you could try replacing your loudspeakers - different loudspeakers (brands/types) sound very different. I'd go to an audio shop and listen to and compare different speakers (and I'd personally do it without any salesperson standing beside me, commenting on the sound!). You can also take your favorite music to the shop and use it to compare different speakers.
     
    Last edited: May 30, 2014
  9. May 30, 2014 #8

    nsaspook

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    What you are mainly doing is extending the horn that is your ear for a better impedance match of the free air sound waves to the ear canals acoustic impedance at that frequency range. If you cup your hands in front or behind the ear the effect at low frequencies is about the same.

    http://en.wikipedia.org/wiki/Horn_(acoustic)
     
    Last edited: May 30, 2014
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