Exercises

1. What frequency would you hear if you synthesized a sine wave at 88000 Hz. at a sample rate of 44100?

2. Draw a block diagram showing how to use thresholding to detect when one audio signal exceeds another one in value. (You might want to do this to detect and filter out feedback from speakers to microphones.)

3. Using the techniques of section 3.7, draw a block diagram for generating two phase-locked sinusoids at 500 and 700 Hz.

4. Two sawtooth waves, of unit amplitude, have frequencies 200 and 300 Hz., respectively. What is the periodicity of the sum of the two? What if you then wrapped the sum back to the range from 0 to 1? Does this result change depending on the relative phase of the two?