= 1. A spherical waves in air has a produce sound pressure amplitude of 100 dB (Pref: 20μPa), at a radial distance r=1 m from the source. (a) Plot the ratio of amplitude of the pressure P and the particle speed U as a function of various frequencies at that distance. Where density of air po=1.21kg/m³ and speed of sound in air c = 343m/s. (b) Determine the radial distance where the spherical waves approximate the behavior of plan wave within about 10%.

= 1. A spherical waves in air has a produce sound pressure amplitude of 100 dB (Pref: 20μPa), at a radial distance r=1 m from the source. (a) Plot the ratio of amplitude of the pressure P and the particle speed U as a function of various frequencies at that distance. Where density of air po=1.21kg/m³ and speed of sound in air c = 343m/s. (b) Determine the radial distance where the spherical waves approximate the behavior of plan wave within about 10%.