3. Characteristics of Sound

A sound can be characterized by the following three quantities:

(i) Pitch.

(ii) Quality.

(iii) Loudness.

Pitch is the frequency of a sound as perceived by human ear. A high frequency gives rise to a high pitch note and a low frequency produces a low pitch note. Figure 2 shows the frequencies of same common sounds.

 

Figure 2 Frequency and Wavelength of Everyday Sound

 

A pure tone is the sound of only one frequency, such as that given by a tuning fork or electronic signal generator.

The fundamental note has the greatest amplitude and is heard predominantly because it has a larger intensity. The other frequencies such as 2fo, 3fo, 4fo, ............. are called overtones or harmonics and they determine the quality of the sound.

Loudness is a physiological sensation. It depends mainly on sound pressure but also on the spectrum of the harmonics and the physical duration.