Music Speakers. Why have they not evolved like the rest of technology?

Factual Questions
1

Technology has moved on, so why don’t we have better speakers for sound?

The bigger the speaker, the better the sound – depending on the type and make of the device but no matter how you cut it, the thing is still a vibrating membrane over a magnetic disk. Maybe it’s in an echo chamber, or sound tunnel, but it’s still a membrane that vibrates.

I used to use those big headphones for my stereo years ago and liked them because of the quality of the sound. Then, everyone switched to making these compact things, which do not develop the bass I like and to me, sound tinny. Out came the little music things like in cards and dolls, battery powered and using chip technology and they sound like crap in a can.

Now comes the Bowes Radio, but they’re using a sound tunnel attached to high quality speakers.

The cell phone you keep glued to ear or belt: membrane speaker, plastic or fiber. Those major bucks stereo speakers you have holding up a wall: fiber membrane.

We went from tubes to transistors to solid state circutry to chips. We went from a radio the size of a pack of cards to one in a watch. We went from bulky (nearly invincible) black dial phones to wireless and cell, from the size of a phone book to the size of a cigarette pack. From flying a couple of yards at about 30 mph, we’ve reached the moon traveling at thousands of mph. From big picture tubes in TVs to liquid crystal. From hand cranking your 6 cylinder, standard steering, open air car to driving a machine that cradles you in luxury and will show you pictures, display maps and talk to you.

But our speakers have stayed basically the same. Not very efficient. Listen to midi files on standard PC speakers and everything sounds like organ music or cheap electronic. Buy one of those chip recorders for memos and the tiny speaker distorts your voice.

You are not getting full quality sound from your Walkman using those tiny, foam padded headset speakers.

So, what’s up with this? We made magical leaps from steam to internal combustion, to electric to nuclear. From vacuum tubes to micro chips, but not much in the way of speakers.

Why?

2

Try this:

http://www.atcsd.com/HTML/hss.htm

These hypersonic speakers direct a beam of ultrasound to either a person’s ears or to a surface (to be bounced off). Think of it like the spot of a flashlight: you only see the light when it shines on a wall or is pointed straight into your eyes.

3

A better explanation than the company’s own page comes from Discover Magazine, who gave them an award in 1997:

http://www.discover.com/awards/arc97/9707-7G.html

4

The secret to getting deep, rich bass is moving a large amount of air without distorting it (remember, sound is mechanical vibration of the air- a series of alternating compressed & rarefied waves. The lower in frequency, the longer & farther apart the waves are). So far, the best way to do this is with large moving membranes. And the best thing we’ve come up with (that’s commercially practical and affordable by the general public) is to mount these membranes on voice coils & then use amplifiers to pump current through the coils. Remember, the speaker is attempting to reproduce what the tuba player is doing. Ever notice the physical size of most bass instruments? They are big for a fundamental acoustical reason- because of the nature of low frequency sound waves, devices which produce them must necessarily be large as well.

5

I am not a technician, but I do know that speakers have evolved in ways not necessarily visible to the untrained eye. I’m talking about things like efficiency and power handling. Also the materials used to make the cone have changed. These day they’re using things like titanium and mylar instead of cardboard.

Back in the day (god, I hate saying that) it took massive speaker arrays and power amplifiers to achieve the proper sound pressure levels for a live concert. With today’s technology, the number of speakers and amps is half what it was in the 70’s to achieve the same volume (cleaner as well).

To turn your car analogy around – even with all the computers, GPS, anti lock brakes and traction control, your car is still a metal box on four rubber wheels.

We’ll probably get speaker “implants” about the same time we get flying cars.

6

Good question. It’s kind of like the internal combustion engine, which hasn’t changed in over a century.

There have been some departures from the magnetically-driven piston design, such as electrostatic speakers. But the fundamental design of the piston speaker hasn’t changed since its inception many decades ago.

Off the top-of-my-head, I can think of two reasons:

  1. The design is mature, and cannot be easily modified without introducing negative characteristics such as distortion, lower dynamic range, inefficiencies, etc. Like so many other things, a speaker is a classic example of designing around “tradeoffs,” i.e. change one thing for the better and something else goes to hell.

  2. If you want to improve on it, the only quantum leap you can make (IMHO) is to make a pulsating sphere. Now let me see you try to make that.

7

. . . which is correct, but-

Size is becoming less of a factor. I’ve seen a sound system where the subwoofer was no bigger than a portable TV (about 20" cubed) that put out tremendous bass levels.

8

Three different (but related) answers to choose from:

  1. It’s simply that no one has come up with anything.
  2. There actually have been advances and they’re still happening.
  3. The problem is just too simple – no room to improve.

#3 first: In the field of aerospace, say, you can modify fuel, engine design, vehicle shape, computers, landing/take-off paradigms, … Just the engine design itself provides literally thousands of important variables.

The statement of the acoustics problem, though, is painly simple: make air vibrate like this (where “this” is defined as “how the original live instrument sounded.”) The task of miking, recording, playing, and amplifying the sound and its signal is not part of the question here, so we’ll assume it’s done. Our task is to make something that can couple to the air, making pressure increases and decreases over and over at frequencies ranging from nearly 10 Hz to over 20 kHz.

There aren’t many variables:

  • coupling method (a membrane is nearly the only way)
  • parameters of membrane (weight, how it’s held, shape, etc.)
  • how the membrane is moved (electromagnet, electro"static" field (not really static), etc.)
  • surrounding materials (shape, makeup, rigidity, wieght, etc.)

To make bass sounds, you need a longer, slower stroke. For high frequencies, you need something that can change direction quickly. Making a single driven membrane that moves both of these ways is the fundamental (insurmountable?) difficulty. Also, we evolved to hear sounds made from people-sized objects, so if we want to fool our senses, we’re going to need macroscopic speakers (i.e., not headphones.)

#2, then: The technology is there. You can get speakers that will not be the limiting factor in your sound quality (assuming you aren’t listening to a live local feed of music.) Your amplifier, listening environment, and (mostly) your source are going to be culprits first. And while such speakers are pricey, they aren’t that pricey.

#1, finally: All this is fine and good, but maybe it’s just that no one has thought far enough outside the box. Maybe there is some way to make a single, small, all purpose, perfect speaker. One tends to feel, though, that there isn’t, as the problem is somewhat analogous to, say, trying to make a smaller chair. The only way I can think to make something radically different is to bypass the air/eardrum combo all together (going straight to the middle ear or further), but that’s a little silly.

To comment on some of your other statements:

It’s not the speaker’s fault in either case. You can patch a MIDI file through the most expensive setup in the world and it’ll still sound like organ music. And those chip recorders just don’t store a lot of bits. Same thing. (Albeit, the tiny speaker is probably doing a little bit of damage.)

Hmm. In preview, I see much of this post has become redundant. Oh well.

9

Does anybody remember those PLASMA SPEAKERS of a few years back? I don’t remember the name, but I believe that they were made by a british firm. And they were very expensive!
To add to the discussion, Dr. Amar Bose (of the Bose wave radio) supposedly was able to simulate the ideal speaker (the pulsating sphere) with his reflected-sound speakers. Oddly enough, a lot of audiphiles DON’T like Bose speakers-why I don’t know.

10

See my lengthy post here.

We do.

But none of the advances made in the last century have been able to change the laws of physics.

You equate better with smaller. And you’re wondering why small speakers don’t sound good. Small speakers just can’t produce low frequency sounds very well. For a given room, say 2m x 3m x 5m, the woofer must energize 30m[sup]3[/sup] of air with low frequency sound pressure. To energize that much air you need a large surface area speaker cone (or lots of little ones working in unison).

A small speaker such as those in cell phones and greeting cards do produce low frequency sounds, but just not very loudly. The little 1/2" speaker in your cell phone certainly can move back and forth 50 times a second, but the 50Hz sound it produces might be 75dB less loud than the higher frequencies it normally does. And our human hearing is much less sensitive to low frequency sound as well.

The reason headphones manage to audibly produce any low frequency sounds at all, lies mosttly in the fact that the little speaker only has to energize the ~20ml of airspace between it and your eardrum.

And greeting cards? Hell, those aren’t really speakers at all. They are just little buzzers (a technical term!) that produce tones within a 2-3 octave bandwidth.