Nonlinearity of acoustic impedance in air.
Show how the acoustic impedance varies in diferent sound
environments. Especially interesting is to know how shock flow can be
altered by applying sound in the air. What kind of sound should be
applied, in terms of frequency distribution, to achieve the largest
acoustic impedance change for shock flow? (We are talking about air in
the open, not air confined by rigid borders.) Other properties of air
affecting the sharpness of the shock flow may also be described.