AM and Pitch Shifting

Overview

In this project you will experiment with more elaborate uses of amplitude modulation (AM).

Deliverables

One-page memo detailing your results, plus additional attachments as needed. Be sure to include the following:

Part 1 – AM with Sinusoidal Signals

Demonstrate the effect of adding progressively more modulators. For example, begin with an original signal that is a sinusoid. Use a single modulator to split the original sinusoid into two distinct sinusoids. Next, use this result as input to a second modulator to produce a total of four sinusoids. Continue this process for at least four stages of modulation. Use the ‘calspec.m’ function to display the spectra of your signals.

Part 2 - AM with Speech or Music 

Repeat Part 1, but now use a recognizable signal such as a short speech or music clip.

Part 3 - Pitch Shifting with Single Sideband AM (SSB-AM) 

Experiment with the pitch-shifting function ‘ssb.m’. Edit the file to load and process your own signal.

Propose an explanation for why a pitch-shifted signal (such as speech) sounds “odd” compared to a person speaking (or playing an instrument) higher or lower.