(WVS) Characteristics of Sound Waves Lesson

Characteristics of Sound Waves

Since sound is a wave, we can relate the properties of sound to the properties of a wave. The basic properties of sound are: pitch, loudness, and tone.  

The frequency of a sound wave is what your ear understands as pitch. A higher frequency sound has a higher pitch, and a lower frequency sound has a lower pitch. For instance, the chirp of a bird would have a high pitch, but the roar of a lion would have a low pitch. Below is a visual representation of a high frequency high pitch sound wave versus a low frequency low pitch sound wave.

Frequency pitch graph: sound A, trouphs and crests are closer together; sound B: trough and crest are spread out

The human ear can detect a wide range of frequencies. Frequencies from 20 to 20 000 Hz are audible to the human ear. Any sound with a frequency below 20 Hz is known as infrasound and any sound with a frequency above 20 000 Hz is known as ultrasound.

The amplitude of a sound wave determines its loudness or volume. A larger amplitude means a louder sound, and a smaller amplitude means a softer sound. The vibration of a source sets the amplitude of a wave. It transmits energy into the medium through its vibration. More energetic vibration corresponds to a larger amplitude. The molecules move back and forth more vigorously. Below is a visual representation of a loud sound wave versus a soft sound wave.

Amplitude Loud/sound waves on graph: sound B trough and crest are not as high and low sound C: high crest and lower trough

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