How does a single speaker play many simultaneous frequencies?
Question
I've been an avid listener for only the past month or so when I've been listening to the podcasts on my walk to and from the library everyday to revise, and am absolutely loving it so far and have managed to get through a good 30 or 40 of the latest podcasts in this short period of time... Anyway just a few things I was wondering if you could help me with:
As an amateur musician and DJ I have forever struggled to work out how it is that, particular in cheaper more basic speakers, a single speaker cone/diaphragm is able to vibrate at so many different frequencies at any one time in order to produce the full tonal frequencies of a piece of music? So essentially: how is it that it is able to recreate a kick drum at say 70Hz whilst still producing a clear strings note of 1700Hz undisturbed. Thanks very much for your time
Dom Parker
Answer
Dave - If the speaker was to produce a single frequency, think what that actually means - it means that the speaker is moving backwards and forwards, and causing the air to move backwards and forwards in a sine wave pattern.
You've probably seen a sine wave: it's basically just a very specific "zigzaggy / wiggly" line.
Now, if the speaker moves in any other pattern than that - you could imagine it's moving slowly with a big wiggle and then on top of that superimposed, there's a little wiggle - then it would be outputting sound with the low frequency, the big slow wiggle, and also a much higher frequency (the small superimposed wiggle) as well, at the same time. It's just moving the air to make sound waves corresponding to the movements of the speaker.
The way that sound works is you can superimpose the motion of the speaker - meaning lots and lots of different vibrations - and that will produce sounds of lots and lots of different frequencies all at the same time, by just making the right pattern for the speaker to move back and forwards.
这不是朝着一个平滑的摆动,它让莫re complicated movements that are a mixture of lots of different frequencies superimposed on top of one another.
Comments
A simple explanation
A speaker can simultaneously make high and low frequency sounds because the surface of the cone can vibrate at shorter/faster speeds (high notes) WHILE the cone as a whole is moving at longer/slower speeds (low notes). Imagine a simple, deep bass note pulsing every second. The speaker will make a long, slow throw back and forth to move the air for each bass note. The surface of the speaker cone isn't doing too much other than moving along with the overall big back and forth motion. A violin starts to play and sustain a long high note. The surface of the speaker cone will now vibrate to reproduce that high note WHILE the entire cone continues to travel back and forth. A high quality full frequency range speaker is one that has the responsiveness and agility to make those complex manoeuvers.
Thanks!
That's, as you say, a very nice, simple way to think about it!
Thank you for a great answer!
Thank you for a great answer! My brain feels physically bigger after understanding this. jk. I have wondered about this for a long time though.
Thanks
bro I've been wondering about this for along time thanks for answering this for me
Question
How does a speaker produce different sounds?
The answer is above...
The answer to your question about speakers producing different sounds is written above. Was there something specifically that you did not follow?
Agree
Just to agree with Gus, what a great answer! Thanks, I was wondering the same question.
Great answer
Ive also always wondered about this - what a clear concise and brilliant answer :)
Speaker sound
So how does it work if there’s say a long bass note and simultaneously a violin over the top. Does the speaker alternate between each note in slices of time or does t move along a compromise curve derived from both frequencies
Speaker sounds
Anthony, it's explained very well above, but the answer is that the driver moves at the frequency of the bass note, say 60Hz, but superimposed on that movement is a higher frequency of the violin, say 3000Hz. Like a rolling sea that also has smaller wavelets within the large waves. It's hard for a single driver with a fixed mass to move slowly and in large excursions for bass and also very rapidly for treble, which is why good quality speakers almost always use large drivers (move lots of air) for bass and progressively smaller and lighter (=faster accelerating) for mid and treble. These are separated by an electronic crossover which assigns the drivers frequencies they can handle comfortably.
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