Sound waves

I recommend watching this videos, reading again the theory, and doing several times the exercises online, to understand how sound waves work.

Video 1: Sound Frequency Pitch and Amplitude using Instruments.
Video 2: examples of Audacity.
Video 3: Musical instruments illustrate the relationship between pitch, frequency, loudness and amplitude

Exercises: there are useful to prepare the exam. Do it to improve your knowledge about sound waves.
1º Test: it's easier and you can hear the examples
2º Test: you can find more information about sound. Pay attention to the exercises about waves!