For a sound wave,
Speed = Wavelength x Frequency
ν = λ x f
Given that the speed of sound in air = 344 m/s
(i) For, f = 20 Hz
λ1= v/f
λ1 = 344/20
λ1 = 17.2 m
(ii) For, f= 20000 Hz
λ2= v/f
λ2= 344/20000
λ2= 0.172 m
Hence, for humans, the wavelength range for hearing is 0.0172 m to 17.2 m.