GMU:Dataflow/synthesizer

Pitch

“Pd works with two kinds of pitches ­ Hertz or MIDI numbers. The traditional signs: A, B­flat, G­sharp, etc. are not used at all in Pd. Instead all chromatic pitches have MIDI numbers: A4 is the number 69, B­flat4 is 70, etc. The other way to describe pitch in Pd is in Hertz. To understand this, we need to understand a bit about musical acoustics.” (http://www.pd-tutorial.com/english/ch03.html)

“humans ­ depending on age ­ hear pitches between 20 Hz and 15000 Hz. Children can hear up to 20000 Hz; elderly people can often only hear up to 10000 Hz.” (http://www.pd-tutorial.com/english/ch03.html)

Frequency

“The rate at which a sound wave moves in and out is called the frequency. Frequency is measured in cycles per second. The length of a singnal cycle of a waveform is the span of time it takes for that waveform to repeat. People generally hear an increase in the frequency of a sound wave as an increase in pitch. When the frequency of an oscillator is doubled, the pitch of the sound it generates moves an octave up. For example, an oscillator generating a signal that repeats at the rate of 440 cycles per second will have the same pitch as middle A on a piano. An oscillator generating a signal that repeats at 880 cycles per second will have the same pitch as the A an octave above middle A. A common way of saying "cycles per second" is "Hertz," abbreviated "Hz.”” (http://beausievers.com/synth/synthbasics/)

“It is possible to simply count the number of [vibration] periods in a second. This number is a vibration's frequency and is measured in "Hertz" (Hz); frequency in this context always means how often something repeats in one second (expressed mathematically: 1/second).” (http://www.pd-tutorial.com/english/ch03.html)

Waveforms

• Sine
• Sawtooth
• Square
• Triangle
• Pulse

(Samples could be downloaded/listened at http://beausievers.com/synth/synthbasics/)

Sample rate

“Objects like "osc~" generate a very fast sequence of numbers between -1 and 1 that is sent to the speaker by the "dac~" object. To be specific, 44100 numbers per second are generated and sent. The loudspeaker makes 44100 tiny movements between -1 and 1 within one second. This number, 44100, is called the sample rate.” (http://www.pd-tutorial.com/english/ch03.html)

Volume

“The volume of a vibration is determined by its amplitude, which is the degree to which the membrane is displaced outwards or inwards with respect to the neutral position at rest (the zero position). The greater the membrane's movement, the louder we perceive a sound to be. A representation on an axis looks like this”(http://www.pd-tutorial.com/english/ch03.html)

References

• http://www.pd-tutorial.com/english/ch03.html
• http://beausievers.com/synth/synthbasics/