How Does a Speaker Produce 2 Instruments' Sounds Simultaneously?

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Discussion Overview

The discussion centers around the ability of a speaker to produce multiple sound frequencies simultaneously, specifically examining how a single speaker can generate the sounds of different instruments, such as a kick drum and a Shakuhachi flute. The conversation touches on concepts from acoustics, signal processing, and auditory perception.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how a speaker can produce two different frequencies at the same time.
  • Another participant suggests that vibrations can be superimposed on one another.
  • A different participant argues that speakers cannot produce multiple frequencies simultaneously, referencing a statement by jaap de vries about superimposing frequencies with a single speaker.
  • One participant explains that any acoustic waveform can be decomposed into a sum of pure tones through Fourier analysis, emphasizing the principle of superposition in linear systems.
  • Another participant notes that the signals from both instruments add together in the speaker, as they do in the amplifier and microphone, and highlights the brain's ability to separate these sounds.
  • A later reply mentions that the ear decodes the complex waveform using a single diaphragm, not accounting for the other ear.

Areas of Agreement / Disagreement

Participants express differing views on whether a speaker can produce multiple frequencies simultaneously. Some support the idea of superimposition and signal processing, while others contest this notion, leading to an unresolved debate.

Contextual Notes

The discussion involves assumptions about linearity in systems and the capabilities of human auditory perception, which are not fully explored or defined.

RipClaw
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I am quite confused how a speaker can produce two or more different frequencies at the same time ?

Let's consider one instrument to be the thud of the kick drum
Let the second instrument be a Shakuhachi flute. (From Enigma Sadeness)
Let us have only one speaker( like in most of the headphones)

Now how is the speaker able to produce the sound of both the thud & the flute at the same time ?

Considering the sound of the flute to be 5KHz, and the kick drum to be 100Hz, how is the speaker able to move at both frequencies at the same time ?
 
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You can have vibrations superimposed on one another.
 


I am quite confused how a speaker can produce two or more different frequencies at the same time ?

They cant. As jaap de vries stated, you can only superimpose frequencies with a single speaker.
 


You can decompose any acoustic waveform into a sum of pure tones. This is called Fourier analysis, and it rests on the principle of superposition: you can simply sum up independent signals to get the resulting output, so long as the system is linear.

That is exactly the case you are asking about. The speaker output is the superposition of two frequencies, and your ear performs the Fourier analysis to separate the tones. This breaks down if the system turns non-linear (i.e., if you turn the volume up too high the sounds get distorted and fuzzy. You hear distortion products that aren't present in the original signal.) All is good when the system is linear.
 


The signals (in this case, the pressures) of both instruments add in the speaker just as they already added in the amplifier, in the microphone, and in the air - and as they add in your ears.

The miraculous part of the operation is not that they add, but that your brains is capable of separating them. This is something machines do very badly.
 


You can also consider than your ear is decoding this complex waveform while using only a single diaphragm (not counting your other ear).
 

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