Lab 4: A few functions

Here’s a simple program that plays a note:

(require rsound)

(require rsound/utils)

; given a note, produce a sound containing a pure 1-second tone

(define (note pitch)

(make-tone pitch 0.1 44100 44100))

(play-rsound (note 440))

This program defines a new function, note, that saves us the trouble of typing make-tone over and over again.

First, use the note function to define a short song. Perhaps "Mary Had a Little Lamb?"

Next, define a new function, arpeggio, that accepts a pitch and produces a new sound that plays the given pitch, then a note a major third above it, then the note a fifth above it, then the octave.

This is nice, but the length of the note is fixed. Define a note/d function that accepts both a pitch and a duration, and produces a sound playing the given note for the given number of frames.

Now, define arpeg/d that is like arpeggio but also accepts a duration.

Use these new operators to play a song.

If you finish, ask me for more!

1 Sound operators

Here are the sound operators we know about:

read-rsound : string -> rsound

write-rsound : rsound string -> (void)

play-rsound : rsound -> (void)

rsound-clip : rsound number number -> rsound

rsound-append* : (listof rsound) -> rsound