Just use the keyboard to play an octave from a piano. Use the "octave", "semitone", and "cent" sliders to transpose the pitch to your liking. You can also use the normal 21 included Scratch instruments. * * * MUSICAL INFORMATION A semitone (or a half step) is the pitch distance from one key's pitch to the next, black or white. So a semitone above A4 is A#4. Twelve semitones make an octave. An octave is the distance from one key to the next black or white key with the same name. So, an octave above A4 is A5. A cent is a hundredth of a semitone. So, by setting the cent slider to 50, you could half-sharpen everything. Or, in addition, set the semitone slider to -1 to half-flatten everything. (More of that topic here if you're interested: https://en.wikipedia.org/wiki/Quarter_tone )
I discovered in a music notation program that you can add half-flats and half-sharps, so I went to Wikipedia to learn more. Thank you to Wikipedia for sparking the interest.
