How do TINY speakers produce such BIG sound?

[Andy]

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?

 

[J. B. Wood]

Over the last few years electronic devices have produced some impressive
sounds from a tiny crappy looking almost-flat speaker.

So how is it done?

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: (e-mail address removed)
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

 

[Sam Wormley]

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?

Look at nature... birds, for example.

 

[CWatters]

Over the last few years electronic devices have produced some impressive
sounds from a tiny crappy looking almost-flat speaker.

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.

 

[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.

 

[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.

 

[DaWalRus]

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.

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.

 

[Michael C]

Look at nature... birds, for example.

Most birds have very little freq range, it's much easier to make something
louder if the freq doesn't change much.

Michael

 

[Lostgallifreyan]

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?

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.

 

[Jan Panteltje]

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.

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.

 

[Jan Panteltje]

Look at nature... birds, for example.

Idiot

 

[Kalman Rubinson]

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.

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

 

[Paul]

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

See if you can figure out how the ear works, by reading this
Damned complicated. Second link has pictures.

http://en.wikipedia.org/wiki/Auditory_system
http://thalamus.wustl.edu/course/audvest.html

Paul

 

[Joerg]

Hello Michael,

Most birds have very little freq range, it's much easier to make something
louder if the freq doesn't change much.

Not the ones out here in California, they can sing rather pretty songs.
And loud.

Regards, Joerg

http://www.analogconsultants.com

 

[Alex Coleman]

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,

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

 

[Kalman Rubinson]

See if you can figure out how the ear works, by reading this
Damned complicated. Second link has pictures.

http://en.wikipedia.org/wiki/Auditory_system
http://thalamus.wustl.edu/course/audvest.html

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

 

[Lostgallifreyan]

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

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.

 

[dannysdailys]

J. B. Woodwrote:

Over the last few years electronic devices have produced some impressive
sounds from a tiny crappy looking almost-flat speaker.

So how is it done?

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: (e-mail address removed)

Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337[/quote:cf5c155e51]

I'm sorry, I would have to disagree. Speaker technology hasn't really
progressed at all. Other then certain devices using flat panel tech,
which includes my Monsoons on this computer.

All Bose has ever done, starting with their 301 home series speakers,
is seriously distort the sound field. By dispersing left and right
channel information into the wind. They no longer have a hearable
left and right localized sound. Hardly what the artists intended.

Cone tech, other then using carbon fiber cones, hasn't advanced since
the 70's. Today's Sub Woofers were yesterday's bass speakers. Only
now, you only get one! Who's kidding who?

The only thing I've seen is a huge quality drop in fidelity products.

Topped off with the introduction of MP-3's.

Yesterday's CrO2 cassette tapes can wipe the floor with an MP-3.
MP-3's are sonically laughable and so are most of the speakers you
see at stores.

My midrange is an 8 inch speaker. How big are today's woofers? 8
inches tops?

Sorry, I'd have to say "get real."

 

[CBFalconer]

.... snip ...

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.

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.

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More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

 

[Peter Dettmann]

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.

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