How Speakers Work
Sound sources generate and transmit vibrations at specific frequencies and intensities through a medium, as discussed in the article on the subject of sound mechanics. The listener’s experience of sound is the result of the vibrations in the ear being converted into electrical signals in the brain by special hairs in the ear.
Here, we’ll discuss the science and theory underlying how speakers produce sound.
History of Speakers
The dynamic loudspeaker of today is a brilliant engineering achievement.
Two American scientists named Edward W. Kellog and Richard W. Rice copyrighted it in 1925, after British physicist Oliver Lodge made the first discovery in 1898.
The design of these early loudspeakers was a little different than the current models.
Due to the high expense of permanent magnets at the time, they employed two electromagnets instead of permanent magnets.
When it comes to creating sound, magnets are just one of several crucial components that all play a role.
The following are the major components of a dynamic loudspeaker:
A rudimentary knowledge of electromagnetic and electricity is required to understand how these components work together to produce sound.
Faraday’s Law of Induction
A physical law known as Faraday’s law of induction states that as electricity flows through a wire, it forms a magnetic field that circles the wire.
In a speaker, for example, the voice coil is wrapped around a piece of copper wire, which creates a magnetic field with two opposing poles.
An electromagnet is the name given to this device.
Electricity passing through the coil affects the strength of an electromagnet.
To increase the electromagnet’s strength, the producer may insert an iron core inside the coil’s core.
A type of electricity known as alternating current occasionally reverses the direction of the flow of current.
Using a sinusoidal waveform, we can depict an alternating current electrical signal.
Like sound waves, the waveform below has a frequency (in Hz) and an amplitude (in dB).
The number of complete wave cycles (one peak and one valley) per second is all that is required to determine the frequency.
Electricity to Sound
Almost everyone is familiar with the principle that two magnets attracted to one another will try to move apart.
Opposing poles attract each other, while the same poles repel.
Electromagnets (the voice coil) and magnets (the permanent magnet) are used to create movement in a speaker.
A doughnut-shaped permanent magnet holds the voice coil in place.
For a voice coil to generate an electromagnetic field it must have electricity flowing in and out of it.
As a result, there will be no interaction or movement.
When electricity is flowing, an electromagnetic field is generated.
They interact with each other, resulting in a movement of the voice coil that is suspended.
Electrical Power = Loudness
The amount of electrical power flowing through the voice coil can be used to alter the strength of the electromagnet and, by extension, the amount of movement the voice coil makes.
There will be a bigger displacement of voice coil from its equilibrium position with more electrical power applied.
The higher the signal amplitude, the greater the power.
Increasing the amplitude means increasing the power and volume!
Signal Frequency = Sound Frequency
The voice coil’s movement frequency can also be adjusted.
The electromagnetic field’s poles will flip places when the voice coil is powered by an AC electrical signal.
The voice coil’s interaction with the permanent magnet changes as the poles shift.
It causes the voice coil to oscillate back and forth at the same frequency as the AC signal.
Look at the diagram again.
The diaphragm/cone is directly connected to the voice coil.
As a result, we may regulate the cone’s motion by altering the amount and frequency of the voice coil’s motion.
While vibrating, the cone emits pressure waves of the same frequency as the alternating current (AC) signal transmitted to the speaker.
Sound is another name for these airborne pressure waves.
The Role of DAWs
There are a slew of DAWs (digital audio workstations) out there that can convert your musical ideas into AC electrical signals, including FL Studio, Ableton, Reaper, Cubase, and ProTools.
In order to produce music that can motivate people to dance, sing, scream, or yell, the signal instructs the speaker what to do and how to move and behave.
As far as I’m concerned, this is a fantastic idea that borders on magic.