A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 m s−1.

Solution:

For sound waves,

Speed = Wavelength × frequency

v = λ × v

Speed of sound wave in air = 344 m/s

(a) For v = 20 Hz

λ₁ = v/v₁ = 344/20 = 17.2 m

(b) For v₂ = 20,000 Hz

λ₂ = v/v₂ = 344/20,000 = 0.0172 m

Therefore, for human beings, the hearing wavelength is in the range of 0.0172 m to 17.2 m.