How do TINY speakers produce such BIG sound?

Over the last few years electronic devices have produced some impressive
sounds from a tiny crappy looking almost-flat speaker.
For example, many cells phones have a "no hands" mode where the tiny
speaker easily projects the sound for several yards.
Another example is my USB memory device which can also play music. The
sound is not hi-fi but its very impressive for such a tiny speaker.
How the heck is this done?
(1) Is it done by better components like stronger magnets, stiffer cone
materials, longer or shorter(?) throw voicecoils, etc.
(2) Is it done by acoustic processing (like SRS Labs's "WOW!") but I
don't think that was so available a few years ago when the better
speakers started showing up.
So how is it done?
Reply to
Andy
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Hello, and I have witnessed the same thing. The perhaps unexpected volume and fidelity can be attributed to speaker design/quality, enclosure acoustics and speaker siting within the enclosure. Capability does not always correlate to bulk. There are small high-end audio bookshelf and pedestal-mounted speakers whose performance equals or excceds that of their larger brethren. Even a low to middle end producer like Bose has done some impressive things with their "acoustic waveguide" design. Granted these transducers are larger than that found in hand-held equipment. Signal processing such as Dolby NR can certainly provide enhancement although I'm uncertain as to what is used in cell phones. I would expect acoustic signal processing to be applied more in a device designed to reproduce music.
Another acoustic/psychoacoustic phenomenon relating to fidelity that comes into play is that of the "missing fundamental" (you can Google for further into). Which is why some of us still remember getting decent rock and roll sound from shirt pocket sized AM transistor radios. Sincerely,
John Wood (Code 5550) e-mail: snipped-for-privacy@itd.nrl.navy.mil Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375-5337
Reply to
J. B. Wood
even some headphones with a 8mm diameter speaker can sound good.
At high power levels the cone has to move quite a long way. I believe that suspending a small cone so that it can move a long way is the hard part.
Reply to
CWatters
there are two parts to the moving cone issue: it's also important that the wave can't somehow get to the back side of the cone -- that makes it 'reactive' and reduces the engergy actually transmitted into the air. It might worth thinking about how the ear works -- that little drum moves enough even with low fequency waves well enough for us to hear them.
Reply to
Tony
there are two parts to the moving cone issue: it's also important that the wave can't somehow get to the back side of the cone -- that makes it 'reactive' and reduces the engergy actually transmitted into the air. It might worth thinking about how the ear works -- that little drum moves enough even with low fequency waves well enough for us to hear them.
Reply to
Tony
Ever see the old device that was just a magnet with a voice coil and a wood screw that you could mount on a door for example that would use that to resonate? Good example of the ear the way the tiny drum resonates the body.
Reply to
DaWalRus
Most birds have very little freq range, it's much easier to make something louder if the freq doesn't change much.
Michael
Reply to
Michael C
Andy wrote in news:Xns97BF73E7A23FB74C1H4@127.0.0.1:
There is an old mediaeval instrument called the Racket (I kid you not, nor is it viol...). This racket is a folded tube, that runs back on itself several times within an overall box-like structure. It's small enough to hold in front of your head like a bulky trumpet, but produces a bass more full than a bassoon. I think the makers of mobile phones might have consciously studied that idea to get their extended response. There is something tonally similar to the racket, and I'm only partly being funny about that. :)
In short, the secret is in coupling the movement of a diaphragm to the air to get long waves efficiently. Good coupling to the waveguide to avoid the need for excess power. This might result in monotonal bass, but careful selection of the fold points in the waveguide will reinforce enough harmonics to make the sound musically useful. The payoff is a curious timbral overlay to the original input, and that is a very familiar quality in the sound from a mobile phone. Old audio players would boom too, but the difference here is that this property has been explored and used effectively by revisiting some very old ideas in music making.
Reply to
Lostgallifreyan
On a sunny day (Wed, 10 May 2006 11:23:38 +0100) it happened Andy wrote in :
As people do not seem to pay attention anymore to 'distortion', most modern cellphones use pulse width modulated audio amps for better efficiency, longer battery life, and more power. Small powerful speakers have been around since the sixties.
Reply to
Jan Panteltje
Not really. The ear drum is compliant at audio frequencies and the woodscrew is not. Besides, the ear drum does not "resonate(s) the body."
Kal
Reply to
Kalman Rubinson
See if you can figure out how the ear works, by reading this :-) Damned complicated. Second link has pictures.
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Paul
Reply to
Paul
Hello Michael,
Not the ones out here in California, they can sing rather pretty songs. And loud.
Regards, Joerg
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Reply to
Joerg
Thanks. Not necessary. Those pages are OK but superficial and, in a number of small details, misleading. Try the Kandel book referenced in the Wikipedia page for more info (although it is getting a needed update shortly).
Kal
Reply to
Kalman Rubinson
Alex Coleman wrote in news:Xns97BFC8E4ED5AD71F3M4@127.0.0.1:
Sounds like the 'Bass Maximiser' in the Hyperprism DirectShow effects, which transfer energy from the fundamental to the harmonics. It's not exactly missing, it's just reduced relative to the harmonics, which our hearing infers the fundamental from. I think it's a horrible effect. A better way to get more bass energy to be perceived is to tighten the envelope decay, so you stll need more bass handling capacity, but only for short pulses. Even if the decay drops back sharply before an extended fade, we still hear it as if it was full. That trick might not be used in mobile phones, but it's definitely been used in radio to get a solid rock sound from a small radio.
Reply to
Lostgallifreyan
... snip ...
Look up the Klipshorn, and folded horns in general. The latter often use the corners of a room as the final part of the horn mechanism, and can be very efficient.
Reply to
CBFalconer
Yes it is not the cone size that is important, it should only pump the air. It is how the cone is coupled to the outside world. An example is the exponential horn loud speaker, where a very small cone is efficientl coupled to the real world. The closer a design can get to this is what one would aim for. The practical problem with a really good exponential horn is of course due to space considerations.
Peter Dettmann
Reply to
Peter Dettmann
they produce great sound because of the nano drivers they have installed within them. Take bose for example, they used the latest technology to surround you in music, movies, games, etc.
Reply to
spencer anderson

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