Sounds and Spectrograms

Objective

The purpose of these demos is to learn both a visual and audio connection between sounds and their waveforms. This connection will be built by listening to some sounds and then seeing what they look like as a function of time.

Then we'll see how their frequency content evolves over time by looking at the spectrogram. This leads to a second connection between the sound and its frequency content.

Test Signals

Many of the test signals were generated via MATLAB, but some are recordings of "real" signals. For the simpler cases, the time signal is plotted, but for all cases, the spectrogram is shown.

Simple Sounds Cosine wave, square wave, triangle wave, & beat note
Real Sounds Synthesized music, real piano, toy whistle & human speech
Chirp Sounds: Synthesized & Real Slow chirp rates
Wideband Frequency Modulation (FM) Fast chirp rates

The chirp and FM sounds were generated with MATLAB. You could use them to test how well you understand the spectrogram.

McClellan, Schafer, and Yoder, Signal Processing First, ISBN 0-13-065562-7.
Prentice Hall, Upper Saddle River, NJ 07458. © 2003 Pearson Education, Inc.