Building a sound and breaking it down.

Abstract

The sounds we hear everyday are made up of acoustic waves of many different frequencies. When a sound is dominated by waves of a particular frequency, it is referred to as having a certain pitch. However, even single musical notes are often made up of various different frequencies (usually harmonics of the first). This is part of what gives different musical instruments their distinctive sounds. Our ears analyze sounds, with different nerve endings being activated by waves of different frequencies. This breaks sounds down so that we can distinguish different pitches or even chords. This breaking down of sound, showing its loudness as a function of frequency, is called finding its spectrum. In two hands‐on experiments, we will use a computer to visualize the building and breaking down of sounds. First, we will use a keyboard as a wave generator to incrementally build up a sound from waves of different frequencies, all the while using a computer to show us the spectrum of the resultant sound. Second, we will record you singing an “ah” or “oo” sound and examine its spectrum to show all the frequencies involved.