
The shaping and manipulating of representations of sound by an electronic music system. 


An instrument that produces an analog or digital representations of sound, which the user may design. 


An instrument represents sound as voltages 


An instrument represents sound as a series of discrete numbers 

Electroacoustic Transducer 

An electroacoustic transducer converts electrical energy to acoustic energy There are always relatives between the two types of energy.
Fluctuations in voltage are analogous to fluctuations in air pressure.
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An electrical signal that represents sound by containing voltages that fluctuate analogously to the fluctuations contained in the air pressure. 


Fluctuations in voltage are converted to imprints on magnetic tape, then back into an analog signal by tape player. 

Analog to Digital Converter 

a device which changes an analog signal to a digital representation of sound. This digital representation is a series of numbers that represents the fluctuating voltage of the analog signal
Once in digital form the signal may then be shaped and modified using digital tools. It may also be sent to tape or disk where it is encoded and stored as a digital recording. This type of recording is called a digital recording because the sound is stored as a series of discrete numbers. 

Digital to Analog Converter 

a device which takes the series of stored numbers, the digital representation of sound, and changes it back to an analog signal. 


A graphic depiction of sound
Shows fluctuation Air pressure, voltages or digital values over time. 


The process of converting and analog signal to a digital representation of sound by taking measurements of instantaneous amplitudes at equally spaced time intervals. 

Timedomain representation 

Waveform shows Amplitude changes through time proceed.
Focused on depiction of Amplitude. 

FrequencyDomain Representation 

A graph of all frequency components of sound. 


refers loosely to the strength of the waveform in terms of the amount of fluctuation between the peak positive value or the peak negative value and the zero axis 


the rate at which one cycle of a waveform is completed. Measured by the number of cycles per second (Hz)
XAxis 

Frequency vs. Pitch (Directly correlated) 

Frequency is the physical property of sound
Pitch is the listener’s interpretation of frequency 


The term phase is used to specify a specific point in time on a waveform
Phase can also be used to compare the relative position in time of two waveforms 


The rate at which measurements of amplitude are taken – expressed in samples per second – like frequency, measured in Hz
The sampling rate directly affects the quality of the conversion – higher rates mean a better representation of the original sound – higher sampling rate = bigger files and more processing power needed 


False or alias frequencies that arise from a sampling rate that is too slow in the analog to digital conversion process. Also called “ Fold over ”
Samples must be very close together in order to create a convincing illusion of continuous sound
Unwanted frequencies produced when a sound is sampled at a rate less than twice the highest frequency component in the sound. 


False or alias frequencies that arise from a sampling rate that is too slow in the analog to digital conversion process. Also called “ Fold over ”
Samples must be very close together in order to create a convincing illusion of continuous sound
Unwanted frequencies produced when a sound is sampled at a rate less than twice the highest frequency component in the sound. 


A sampling rate two times the highest frequency contained in a waveform. • To Avoid aliasing: sample at a rate of at least twice the highest frequency in a sound. • At least two data points per cycle guarantees frequency. 


The number of discrete amplitudes a digital system can represent. • Expressed in terms of the number of bits used to store each amplitudelevel • Also called Quantization • Detail and dynamic range 


Fourier Analysis: named after the nineteenth century French mathematician Jean Baptiste Fourier, enables one to break down complex periodic waveforms into their basic components, which happen to be sine waves of various frequencies, amplitudes, and phases.
Fourier Synthesis: The opposite method, combining sine waves of various frequencies, amplitude, and phase to create complex periodic waveforms, is Fourier Synthesis.
Additive synthesis is a synthesis technique that is based on the combining of simple waveforms (usually sine waves) at a various frequencies, amplitude and phases to create a more complex waveform. 


Frequency is uniform • Smooth, “pure” sound • Generally regarded as the most basic waveform, thanks to Fourier 


the frequency component that has the same period as the waveform 


any frequency in a waveform higher than the fundamental 


a frequency that is a wholenumber multiple of the fundamental
the fundamental is the first harmonic of the harmonic series 


any harmonic other than the fundamental
the first overtone is the second harmonic 


Contains all harmonics • amplitudes in a ratio of 1/harmonic # • even harmonics 180 degrees out of phase • has a buzzing sound to it 


Contains only odd harmonics • amplitudes in a ratio of 1/harmonic # squared • every other harmonic is 180 degrees out of phase • smooth sounding, like a clarinet 


like the triangle wave, contains only odd harmonics • like the sawtooth wave, amplitudes in a ratio of 1/ harmonic # • all harmonics in phase 


subtractive synthesis a synthesis technique that is based on the removal or attenuation of specified frequencies by a filter 


allows only certain frequencies to pass • basic part of almost all synthesis systems • Cutoff Frequency: the specific frequency above which, or below which, (depending on the filter type) frequencies are removed or attenuated. 


Attenuates frequencies above the CUTOFF FREQUENCY while allowing frequencies below the cutoff to pass unaltered – The difference between the input and the output is called the FREQUENCY RESPONSE 


Attenuates frequencies below the cutoff 


allows a specific band of frequencies to pass while attenuating others 


opposite of bandpass; attenuates a specific band of frequencies while letting others pass 


when regeneration is increased, the frequencies around the cutoff increase are given more prominence 


a graphic depiction of how a filter, synthesis module, or other electronic device responds to a signal. 


The difference between the input and the output is called the FREQUENCY RESPONSE 
