Headphone Heights

How do MEMS produce bass in earphones?

73.11.33.151

BobH

I understand how microelectronic machine systems are made in silicon. So how do these VERY small vibrations create bass frequencies that we can hear? Do slow pulses fool us into thinking we are hearing long wavelengths? Dumb question but . . .

Follow Ups:

Not MEMS? - BobH 18:09:38 03/21/15 (4)
Maybe the "microdrivers' Shure uses are not MEMS. Same question though: how does such a small driver produce bass down -3dB at 90Hz?!! Anyone? Anyone?
- "Small" is relative - genungo 06:16:11 03/22/15 (3)
  A small driver pressurizing air in a small space is in most respects equal to a larger driver pressurizing air in a larger space. Sound pressure is the issue.
  It has been said (by some at least) that deep bass cannot not be reproduced in a loudspeaker system unless the listening room is of a certain size. This has proven to be patently false, because loudspeaker systems in small rooms and headphones can and do reproduce deep bass. Sound pressure level is the primary issue.
  With headphones, you are dealing with a miniature loudspeaker system. As long as the headphones are well engineered and a proper interface or fit on a person's head has been established, the full frequency range of sound can be reproduced in this miniaturized environment.
  
  Edits: 03/22/15
  - RE: "Small" is relative - BobH 09:43:37 03/22/15 (2)
    Thanks, this is what I am looking for, although my physics is rusty.
    Sound pressure level is basically force, right? Is that why larger woofers produce lower bass, because the larger cones produce more force against the volume of the air in the room? By analogy, the "microdrivers" in IEMs have only to produce that force into the small volume of the ear cannal with a well fit IEM. Correct?
    
    The second question was what the mechanism is of the "microdrivers". Any idea how that is done? The images on the Shure site show multiple layers of presumably silicon. Are these small etched panels that move the air? I cannot find any reference to this on the web except MEMS which don't appear to be in production yet.
    - RE: microdrivers - genungo 11:35:43 03/22/15 (1)
      Have not heard anything about Shure's "microdrivers" yet. As long as they vibrate in response to an electrical signal, I'm sure they'll do just fine...
      - RE: microdrivers - BobH 18:33:17 03/22/15 (0)
        
        In Reply to: RE: microdrivers posted by genungo on March 22, 2015 at 11:35:43
        
        They do sound fine and the bass is surprisingly low which makes me curious. I assume other companies do the same kind of thing so I wonder how it works.

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