By John Payne
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RatioKey provides a dense selection of tones (105 over an adjustable 2-octave range), all related to the center (1/1) tone by frequency ratios composed entirely of low powers of the first five prime numbers (2, 3, 5, 7, & 11). Any two tones with frequencies related by a simple integer ratio constitute what is sometimes called a "pure" interval.
What's New in Version 1.1
Version 1.1 adds the ability to exert some control over the character of the tone produced by independently controlling the volume and duration of each stage of the ADSR envelope. (Caveat: the sound produced is still a simple sine wave with no harmonics.)