Perception of sound
8 Perception of sound: Overview
Sound sources- tuning forks, the strings on a guitar, your larynx when you speak, the cone of a stereo speaker- vibrate. These objects push against the nearby air molecules and force them to vibrate. Those molecules push on the molecules near them and so on. The disturbances in the air travel outward in all directions and eventually reach some sort of detector- like a microphone or a human ear. When the air molecules near the detector vibrate, the sound detector often converts the mechanical vibrations in electrical ones that can be recorded and/or processed. Vibrations that reach the human eardrum get turned into electrical impulses that your brain interprets as sound.
The characteristics of vibrations at the ear play a key role in what we hear. This chapter focuses on the link between characteristics of vibrations- like frequency, amplitude and spectral content- and what humans hear.
Perception of Sound: Learning Objectives
In this part of the book, you can expect to learn how to
- distinguish between measurable characteristics of vibrations at the ear and human perception
- describe connections between
- amplitude and loudness perception
- frequency and pitch perception
- spectral content, envelope and timbre perception
- read and interpret sound graphs
- move back and forth between different ways of representing sounds, including
- words
- time-domain graphs (o-scope graphs)
- frequency-domain graphs (FFTs)
- spectrograms
- explain the role of frequency ratios in musical intervals and spectral content