How do speakers use magnets to produce sound?

Answer 1

Electricity and magnetism combine to create sound in a conventional speaker in a fairly simple way. The basis of this energy conversion isn't that difficult to understand. And yes, it is energy conversion - the conversion of electrical energy (the signal) to mechanical energy (the sound). And if you guessed that a microphone does the opposite conversion, you'd be correct. Let's break down the speaker a bit, but we need to do just a bit of review along the way. Electricity creates a magnetic field around its path of travel. Always. If we take some wire and roll a coil and pass electricity through it, it will create a magnetic field around the coil. (This is the basis for the electromagnetic.) If the electricity we pass through the coil is changing, then the magnetic field it generates will change. (The electromagnet uses direct current.) The changing field will cause the magnetic field around the coil to change. Hang onto that thought and lets look at one more thing. If we take our little coil of wire and attach it to a fairly rigid conically shaped piece of material, we'll have a speaker cone. We'll attach the outer edges of our cone to what is called a "surround" which is flexible. Then we'll attach our surround to a rigid frame. One more thing here. Remember our coil? The one on the cone? We're going to "hang" the cone so that a permanent is inside the coil. Remember that the cone and coil are one piece, and they can move out and in because the flexible surround allows that. And in the "neutral" position where the cone hangs with no signal, there is that permanent magnet (which is fixed to the back of the rigid frame that supports the cone) inside the coil. Got all that? We're set. If we apply a changing electrical signal to the coil, it sets up a changing magnetic field around the coil. This changing magnetic field interacts with the magnetic field of the permanent magnet. The interaction will create a force which will move the coil and cone assembly. It will move the assembly out and in according to the electrical signal. And as the cone moves out and in, it creates a sound wave. The speed at which the cone moves out and in will set the frequency of the sound (the pitch), and the amount the cone moves out and in on each cycle of the signal will set the amplitude of the sound (the volume). That's it! Really!

Answer 2

The magnets in speakers work to absorb the sounds running through the coils. Think of it as a big dust collector and the "dust" in the sound coming through. It amplifies the frequency at which the music is coming out and it captures and pushes it out at an audible volume of sound instead of a frequency of radio waves. That way it turns it into something you can hear from virtually gargled "white noise." The process is similar to how guitar pickups work, absorbing the vibrating sound waves from the strings and picking them up as an electro-magnetic signal, it then passes it through the guitar cable and into the amplifier (which has a speaker with a magnet in it just like the one in a stereo). The process of the speaker is just the opposite of the guitar pickups; one absorbs and changes the sound, then sends it to the other, which amplifies and pushes out the sound.

Magnets are a very amazing audio device, definitely something you should look more into if you are a fan of cool musical experiments, or just want to know more about how the sound systems we all know and love work.