Periodic Signals and Harmonics Exercises  

1. Listen to the sounds of the signals corresponding to the triangular, square, and sawtooth wave at 400 Hz.
   
   
2. Listen to the square wave at the frequencies 100, 200, 400, 800 Hz. What do you observe?
   
   
3. Do you hear any difference between the sinusoidal and the cosinusoidal signals at 400Hz? at 600Hz? Why?
   
   
4. Beat notes can be formed by adding two sinusoids with close enough frequencies (say at 400 and 405 Hz and with amplitude 0.5 and 0.4]. 
   
   
5. Is a continuous-time signal that is composed of  harmonically related sinusoids a periodic signal?
   
   
6. Is a continuous-time signal that is composed of  non-harmonically related sinusoids a periodic signal?
   
   
7. Explain how a sound synthesizer works.