Recording, transmission, playback, and synthesis Flashcards
Microphone
Converts sound waves into electrical signals
Speaker
Converts electrical signal into sound waves
Passes oscillating electrical current through a coil of wire which acts as an electromagnet
The coil exerts a force on a permanent magnet whose direction and strength depends on the current in the wire
The permanent magnet oscillates in a way that matches the electrical signal
Electromagnetic induction
A current is induced in a wire if the wire is in the presence of a moving magnet (or changing magnetic field)
Dynamic microphone
Has the same construction as a speaker, but reversed
Electromagnetic induction converts the motion of a magnet (due to sound waves) to a varying electrical current
Amplifier
Takes in a time varying current
Outputs a current whose time graph is the same shape but with a larger amplitude
Recording (n)
The information about the time graph of a sound wave (which has been converted to a time-varying electrical current) is stored in some physical form
Analog recording (n)
The time graph of the current is directly converted into another form (eg, the shape of a groove on a vinyl disc)
Digital recording (n)
The time graph is sampled a certain number of times per second (sampling rate) and a numerical value is assigned to the amplitude at that point
Sampling rate
The number of times per second that a time graph is sampled in a digital recording
Must be at least twice the frequency of an oscillation to store information about it
Bit depth
The number of possible numerical values (assigned to amplitude) in a digital recording
Synthesizer
Produces sounds by directly manufacturing an oscillating electrical signal (analog synthesis) or a digital version of this (digital synthesis)
Signal is then sent to a speaker
Filters
Applied to the spectrum of a basic waveform produced by a synthesizer
