The Mechanics of Hearing

44 Timbre

Learning Objectives

Know the difference between simple sounds and normal real-world sounds (complex sounds).

Be able to describe what timbre characterizes.

There are two categories of sound covered in this section: simple and complex. Simple sounds are also called pure or simple tones because they consist of a single frequency, though the intensity of that frequency can vary. An example of a simple tone is a tuning fork because the sound it produces is almost entirely only one tone for musical instruments to match. Simple tones do not characterize normal real-world sounds because real-world sounds are more complicated. In everyday life, we hear sounds that consist of the second type of sound: complex sounds (or complex tones). A complex tone comprises two or more simple tones. Complex tones make up the vast majority of sounds we hear day-to-day. Some examples of complex sounds include voices and music.

The tone that has the lowest frequency in the complex tone is called the fundamental frequency, and the other tones are known as overtones or harmonics. The fundamental frequency is what we perceive as being the pitch of a sound. Because the fundamental frequency is the perceived pitch we hear in a complex tone, we say the complex tone is characterized by its fundamental frequency. For example, if a complex tone had three overtones of varying frequencies that were a multiple of 100 Hz, and a fundamental frequency of 100 Hz, the perceived pitch of this sound would be 100 Hz.

 

Three waves are added together to create a complex tone.
Fig.5.6.1. Synthesis of multiple pure tones of varying frequencies to create a complex tone when summed together. Two or more simple tones combined is enough to create a complex tone wherein the lowest frequency represents the fundamental frequency. (Credit: Nicole McCue. Provided by: University of Minnesota. License: CC-BY 4.0)

Timbre is the quality of complex tones produced. The timbre of a sound depends on its waveform, which varies with the number, frequency, and relative intensity of the overtones that are present. Different waveforms are produced by synthesizing (combining) different pure tones of various frequencies and intensities. For this reason, the timbre of a sound varies with the characteristics of the overtones. Two different musical instruments can be playing the same note but have different timbres because they have different complex tones despite having the same fundamental frequency.

 

Sounds are made of many tones which add together to create the complex noises we hear.
Fig 5.6.2 The illustration shows the waveform that results when pure tones of frequencies 100, 300, and 500 Hertz (cycles per second) and relative amplitudes of 10, 5, and 2.5 are synthesized into a complex tone. At the right is the resultant which would be considered a timbre. (Credit: Britannica, T. Editors of Encyclopaedia (2018, February 1). Timbre. Encyclopedia Britannica. https://www.britannica.com/science/timbre)

CC LICENSED CONTENT, SHARED PREVIOUSLY

Encyclopaedia Britannica, Tone
URL: https://www.britannica.com/science/tone-sound#ref895425
License: CC BY-NC 3.0 US
Adapted by: Nicole McCue

Encyclopaedia Britannica, Timbre
URL: https://www.britannica.com/science/timbre
License: CC BY-NC 3.0 US
Adapted by: Nicole McCue

Cheryl Olman PSY 3031 Detailed Outline
Provided by: University of Minnesota
Download for free at http://vision.psych.umn.edu/users/caolman/courses/PSY3031/
License of original source: CC Attribution 4.0
Adapted by: Nicole McCue

 

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Introduction to Sensation and Perception by Students of PSY 3031 and Edited by Dr. Cheryl Olman is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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