How do loudspeakers produce different sounds simultaneously?

[Kermit power]

I understand how a speaker works, and how they vary volume and frequency, but I realised this morning - one of those daft things that gets into your head on your commute and then refuses to go away - that I have absolutely no idea how they produce complex sound?

Think of a typical action film. You might have engine noise, small arms fire, explosions & dialogue, all with dramatic music in the background. How on earth can something as simple as a loudspeaker reproduce all of that simultaneously???

[EliseNick]

How does the microphone record all this complex sound? The speaker simply reproduces the motion of the diapragm of the microphone, and so reproduces the original vibrations in the air.

[Disastrous]

anonymous said:

[redacted]

This. You aren't hearing individual sounds - you'r hearing the one waveform that is created by adding them all together.

[Arif110]

But even then...

I get exactly where the OP's coming from on this. I'm reasonably tech-savvy (you know, jet-engine powered rc cars...) - but in the end, all the diaphragm can do is go up and down, literally. So how on earth can a simple up-down movement cause anything as complex as even simple music to be produced??

I 'get' how you'd get a speaker to buzz or squeal - but beyond that, how??


Arif

[GrumpyTwig]

Arif110 said:

But even then...

I get exactly where the OP's coming from on this. I'm reasonably tech-savvy (you know, jet-engine powered rc cars...) - but in the end, all the diaphragm can do is go up and down, literally. So how on earth can a simple up-down movement cause anything as complex as even simple music to be produced??

I 'get' how you'd get a speaker to buzz or squeal - but beyond that, how??


Arif

Because they move quite fast, you don't feel/hear every explosion of air/fuel mixture in a car engine (maybe discounting really lumpy single cylinder engines ) they all through various reasons merge together into a longer 'rumble'.

Like mentioned it's all just summed up, the speaker moving back and forth for a simple tone would look like a up/down wave, music is just lots and lots and LOTS of waves merge together that the speaker/audio system reproduces with greater or lesser success.
In reality, how do they do it? Well they don't, they just get close, enough for our crappy ears anyway.

[Mr2Mike]

Arif110 said:

But even then...

I get exactly where the OP's coming from on this. I'm reasonably tech-savvy (you know, jet-engine powered rc cars...) - but in the end, all the diaphragm can do is go up and down, literally.

Not quite, the distance it moves, and the speed at which it moves are controllable. A speaker just re-creates the pressure variations in the air that you perceive as sound. It's an odd question really, the difficult bit which people are taking for granted is how the human ear can hear more than one sound at a time.

[Ultuous]

Mr2Mike said:

the difficult bit which people are taking for granted is how the human ear can hear more than one sound at a time.

Indeed - and I guess the best way to explain it is to say that it can't: The ear is 'hearing' 'a' sound, it's the human brain that does the remarkable job of perceiving the components of it as separate entities!

[marshalla]

Who's going to be the first to mention Fourier Transforms ?

Oops!

http://www.askamathematician.com/2012/09/q-what-is...

[Mr2Mike]

Ultuous said:

Indeed - and I guess the best way to explain it is to say that it can't: The ear is 'hearing' 'a' sound, it's the human brain that does the remarkable job of perceiving the components of it as separate entities!

I think it's even a bit more complex than that; the ear itself does quite a bit of pre-processing by splitting the incoming sound into different frequency bands before the brain starts it's job.

[otolith]

Ultimately, you're only perceiving it as deflections of your eardrum.

[T5XARV]

Having acquired, cleaned and serviced a Sansui 5000 amp and a massive pair of Eleganzia Speakers today I decided to pit them against my more modern setup of Denon/B&W's to see who stays and who goes.........one day I will have a set-up I'm satisfied with. Perhaps.

I've been asking myself this very question posed by the OP. Just, how !!!???? and I've spent the evening and half the night testing, listening, positioning, tweaking and I'm astounded by the performance of this 47 year old kit.

Its 3a.m and I'm almost ready to make a decision.....almost.

[Dr Mike Oxgreen]

The OP is asking the wrong question.

Sound is a complex waveform that is the 'sum' of all the myriad noises going on simultaneously. A loudspeaker simply reproduces this complex waveform, which was originally captured by a microphone (or possibly by several microphones and then combined into one signal by a mixer desk).

The really interesting question is how does the human brain separate out all these noises from that single waveform and perceive them separately? And it does it all in real time. That is quite some computing power.

[Hoofy]

Download Audacity, load a few wave files into it. Merge them into one wave file. Mind blown!

[otolith]

Dr Mike Oxgreen said:

The really interesting question is how does the human brain separate out all these noises from that single waveform and perceive them separately? And it does it all in real time. That is quite some computing power.

Exactly - how does it resolve a series of twitches of the ear drum into the distinct parts of an orchestral piece? Incredible.

[V8LM]

We often don't hear all the sound when spoken but the brain fills the gaps with what it thinks we headed - phonemic restoration.

[vx220]

What amazes me is how the different frequencies don't have more affect on each other

There's a pro audio guy on YouTube, shows how a low bass tone upsets a mid range tone, so when speakers are playing so much information it is a tad mind-boggling

[Hoofy]

vx220 said:

What amazes me is how the different frequencies don't have more affect on each other

There's a pro audio guy on YouTube, shows how a low bass tone upsets a mid range tone, so when speakers are playing so much information it is a tad mind-boggling

The effect can be quite noticeable on home audio kit. When you have a kick drum on its own that is joined by some midrange harmony, you can instantly hear a noticeable drop in the volume of the original sound.

[Ultuous]

Hoofy said:

The effect can be quite noticeable on home audio kit. When you have a kick drum on its own that is joined by some midrange harmony, you can instantly hear a noticeable drop in the volume of the original sound.

Which is why each track (read as instrument for the sake of this) it's EQ'd/ given stereo bias at the mastering stage so that it in its own frequency range, with minimal interference with the other instruments.

It's quite funny when I pick a producer mate up for a night out Wren he's been in the studio all day... When he hands me a CD of his latest track, it's not so much that he wants my opinion any more - he just wants to know how the mix sits in my modest hi-fi!

[Hoofy]

Ultuous said:

Hoofy said:

The effect can be quite noticeable on home audio kit. When you have a kick drum on its own that is joined by some midrange harmony, you can instantly hear a noticeable drop in the volume of the original sound.

Which is why each track (read as instrument for the sake of this) it's EQ'd/ given stereo bias at the mastering stage so that it in its own frequency range, with minimal interference with the other instruments.

It's quite funny when I pick a producer mate up for a night out Wren he's been in the studio all day... When he hands me a CD of his latest track, it's not so much that he wants my opinion any more - he just wants to know how the mix sits in my modest hi-fi!

Are you saying that they will allocate a stereo positioning for each track within a certain frequency range?

[Ultuous]

Sorry, wasn't too clear as posting between sets mate! ...

Drums and bass tend to sit centre stage for various reasons, but panning the other instruments (inc. percussion) slightly to the left or right helps them cut through the mix, along with rolling off the stray frequencies (e.g no need to include anything the kick produces above xxx hz, as it just muddies the rest of the sound - dunno if that's just true for dance music or production in general!)