Lab 3

• Read the documentation for the "make-tone" function. Play two overlaid tones whose frequencies are separated by 4 Hz. Next, play two overlaid tones whose frequencies are separated by 2 Hz. Finally, play two overlaid tones whose frequencies are separated by 1 Hz. Do you hear a "beating" between the two tones? How is the rate of the beating related to the difference between the two frequencies? Write your observations in the form of a comment.

  Note: it will be helpful to comment out each call to play after you’ve listened to it, so that the various sounds don’t all play on top of each other.

• Search the web to find the frequencies of the "C Major" scale from middle C up one octave. Develop a program that plays this scale. See if you can avoid redundancy where possible.

• Write code that computes the interval between each pair of adjacent notes in the scale. How many different intervals are present? Write your observations in the form of a comment.

• Do HtDP 2e, exercise 31

• Do HtDP 2e, exercise 34

• Do HtDP 2e, exercise 48

• Design an interactive "kick hat snare hat" program, that plays a sound each time a key is hit. The first key causes a kick, the second causes a closed hi-hat, the third causes a snare, the fourth another closed hi-hat. After this, these repeat: kick hat snare hat, kick hat snare hat, and so forth.

  Hint: think first about what the state of the world should be.

• Design an interactive "rhythm test" application, that tests your ability to place a sound evenly between kicks. It should play a kick drum every second, allow you to play a snare by hitting a key and evaluate your performance. More specifically: When you hit a key, the program should check to see if your keystroke was halfway between the two kicks (to the nearest 1/28 of a second). If so, it plays a ding. If not, it plays a closed hi-hat (c-hi-hat-1).