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?
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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
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I think this is what SRL Labs's WOW technology is all about.
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wrote:

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.
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On Wed, 10 May 2006 19:44:55 +0100, Alex Coleman

No it's about the other parameters of proper design.
A speaker housing and entire device cabinet that doesn't resonant. An amp circuit that can provide the necessary current without severe distortion. A speaker that can likewise handle it.
Many simply thought the size of the speaker was the main criteria when it is simply that small speakers are also more commonly very cheap ones. Someone could make a really low quality larger speaker, put it in a terribly resonant cabinet and drive it will too low a wattage amp and it too would sound terrible... though tend to have more bass.
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wrote:

No again. >:) He's right. There are two diverging methods now. You're talking about the pure form, the striving for true hi-fi, where basic techniques are refined.
THis thread isn't about that though. It's about how speakers small enough to have no chance of rendering real air moving capability without shaking themselves to brittle fatigued pieces, mounted in tiny sealed baffles that couldn't accept such movements without developing deap-sea pressures even if such air movemnt were possible from those little speakers, can still somehow produce good bass. All kinds of non-purist tricks must be used.
Actually, some of those tricks should be used even by the purists. The mani one being panning and balance set by delay and not only by varing the signal level. Try it with a flanger effect, set the feedback to zero, modulation off, and adjust the sub-millisecond delays slowly to afect an already-panned signal. This simulates the tiny delay our heads cause to incoming sounds (That's what the 'head related transfer functions' thing is about, btw). This, combined with subtle low-pass filtering, can make a signal pan well beyond the speakers.
There are several reasons why such tricks are not used in purist hi-fi: 1. Expense. Until recently, it's been prohibitive. 2. Subjectivity. The delay needed to make a degree of panning depends on ear and head shape. 3. The effect has been used as a gimmick, and has got a bad reputation in a purist context.
If I were designing a balance control for hi-fi based on this I'd have a main balance control that had a couple of smaller controls beside it, one for filter, one for delay. To set it up, pan main hard left, then adjust delay for making the sound go to best extreme for proper location left for whoever is going to listen. Check it again on the right, then use the main, then adjust the filter till it feels right. It's more complex than the usual set of controls, but not much. It's no good setting up digital poresets, a thing like that has to be as hands-on as the controls we've got used to over decades.
Not sure whether the bass enhancement thing counts so well for hi-fi use though. It might in active speakers though, where the aim is to match the power gain stage with the transducer to air coupling. When you have that much control over the output device, it probably can get hi-fi results for a small bookshelf system.
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An extra point: If you can try that flanger experiment, set the amplitude on each channel the same. :) What's amazing about this, is the delay part of the panned signal can place the location further left without level difference than the level difference can do without the delay, even when the level is full in one channel and ABSENT in the other!
That should be enough to convince you. But you'll have to do it. Don't just take my word for it.
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On Fri, 12 May 2006 07:51:18 GMT, Lostgallifreyan

I'll take your word for it, because I will always be a purist and never wish for any digital REprocessing of the signal.
I built my own headphone/pre/power amps from scratch though, I'm pickier than most.
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wrote:

Actually I don't either. :) No tone controls, only gain, and two Mackie HR828's (active near/mid-field monitors).
Where those effects really help (and where I learned about them) is in making music. When you use the delay panning carefully you can make very subtle stereo effects that are musically expressive, especially when using noises, close mic'd or ambient, as a source.
The delay panning isn't that bad an idea for general use though, if you've ever experimented with binaural stereo (a long-standing interest for many purists) you'll have already used it. As binaural stereo hasn't taken hold because it's too dependent on head and ear contours, it would have to have the kind of controls I suggest to make it useful to all. Not sure how this could be used to vary the delays in a stereo mix though, unless it be based on splitting the signal into several narrow bands and rebuilding to get the wavefronts aligned. There is a tool that does this, a BBE something, used to clarify poor phase in final mixes. That might be adapted effectively, but I haven't tried one so I have no idea.
About lack of bass, even these Mackies don't go down to the lowest octave, and it doesn't bother be, our hearing can enhance the fundamental without preprocess, so long as there's enough info to start with. By definition, missing the lowest octave means that ONLY the fundamental of those notes is actually 'missing'. :) And it's only attenuated a bit.
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Um, typo, HR424.. No such thing as HR828 as far as I know..
Also, the reason I don't use tone controls isn't beased on the idea of them degrading the pure signal, it's purely that I get used to a sound in a room. If I want to get the balance I don't adjust them except in the crudest and most temporary situation. In stead I play some things I know really well, and shift things in the room if there's some horrible boom in a corner or something.
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HR824. Finally... (Far too used to forums with edit buttons)
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Lostgallifreyan wrote:

Apparently you have connected to another of those flawed interfaces to usenet. This is not a forum. Be aware that a complete world awaits you when you install a newsreader and connect to your ISPs newsserver. I suggest you try Thunderbird, from mozilla.org. Totally free, and available for many systems, including Windoze, Mac, Unix/Linux, etc.
--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
  Click to see the full signature.
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I'm using X-News, a Windows client. I'm not entirely missing the point. :) It's just that I get careless with typing at times, trying to keep up with a thought, and I miss typos and can't edit after posting. It used not to be a problem but I think my sight might slowly be failing.
I know it's technically possible for usenet to allow deletions, and possibly edits, but I think most systems don't allow it because it's easily abused.
I'll look at Thunderbird though, as X-News has some ghastly OS-crashing habits. Not that Firefox isn't free of GUI-affecting memory leaks, so Thunderbird might not be a guaranteed improvement over X-News if it uses common code with Firefox.
All of which is far too much off-topic info, but it might help people avoid making assumptions. :) Sorry, hard to resist that one..
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On a sunny day (Fri, 12 May 2006 05:10:23 -0400) it happened kony
What system, i am curious, electrostatic, dynamic, dynamic wit ha coild in teh membrane? Or piezzo? I once build a smal ldynamic one.... when you find you need permanent magnet bias... Also did some experimenting with piezzo.
Is yours betetr what you can buy commercially? (mine was not).
/pre/power amps from scratch though,
Yes done that too.

Na I am not, listening on PC speakers to my music now:-)
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On Fri, 12 May 2006 10:00:37 GMT, Jan Panteltje

no i meant headamp. I usually listen to Sennheisers or Grados.
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On a sunny day (Fri, 12 May 2006 15:07:55 -0400) it happened kony

OK, I had a Senheiser too. Was very good.
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Me too. Senns seem to have maintained quality in their range with only a few duff models.
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Lostgallifreyan wrote:

My MSI motherboard has a Realtec AC97 six channel sound system. There is a built in demo which uses delay plus volume to "move" a sound source. Now that everything has gone digital it's much easier to implement this sort of thing. I can recall experimenting with screen door springs with phono pick-ups attached, to simulate audio delay.
Made some interesting sounds, but hardly hi-fi!
Virg Wall, P.E.
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Nor is 2-channel stereo. But it's a convention we've come to accept.
Actually, many sounds are processed with delay panning to set a realistic position. WHile it's possible to overdo it, rendering the effect weird for all but the largest ears and heads, there's nothing wrong with doing it in moderation, it just means that those with largest ears and heads will hear it slightly narrower field than most.
The one thing that gets to me about the purist thing is that I've seen people worry about silver speaker cables, or the tiniest differences in an MP3 encoding process, and various other things, when the differences in the musicl process, or the final mix, or even a bit of EQ on the stereo mix, all make far more bold changes to the sound. If it sounds good, people will accept is hi-fi, so long as they don't see that crude assembly of signals at their end.
If you want a great take on that whole thing, listen to a song by Micheal Flanders and Donald Swann. >:) It's called 'A Song Of Reproduction'. It encourages a healthy wariness of too much narrow refinement. The reason why such things as big sounds out of tiny speakers are amazing people right now is that it's taken the computer industry to shift people's perceptions far enough and fast enough to make it possible to try things which have actually been commercially and technically possible for decades. It's the limited concept of what is 'hi-fi' that has had to break down first.
People can agrue till death about how hi-fi is simple, only to reproduce the original sound, but it can't. No two-channel system can. Which is the point, The only way out of a circular argument is to accept new ideas into 'hi-fi'.
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On Fri, 12 May 2006 20:16:31 GMT, Lostgallifreyan

The answer is easy, the goal is not "bold changes", it's accurate reproduction. Some will psychologically err when they assume their further tweaking of audio cables sounds better without an ABX test but even that isn't valid- because multiple changes below a threshold of discrimination (taken alone) can sum to a perceivable difference.
Audio is so subjective though, it's fairly impossible to generalize that "people will accept is hi-fi" when talking about all the possible variations. Even a crude $3 AM radio sounds pretty good compared to silence but set it next to something better... so ignorance can be bliss, the road to perfect sound is long and winding.

Those who do the most critical listening seem to disagree and prefer 2 good channels over digitally mutilated sound. There's nothing wrong with digital at all, to preserve, not change the sound.
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