Experimental results are presented of shock wave and contact front velocity measurements, in air, obtained in a 3 in.×3 in. wave interaction tube. A diaphragm pressure ratio range up to 10 000 was employed, while the distance was varied simultaneously from the origin to 142 in. beyond.It is shown that when shock‐wave attenuation occurs, it consists of two portions; (a) a decrement due to formation, and (b) a further attenuation due to the distance traversed by the shock wave.Concurrently with the attenuation phenomenon, the contact region spreads with time and its front boundary accelerates. The increase in velocity consists of two portions; (a) an increment due to formation, and (b) a further rise in velocity with the distance travelled by the contact front.A satisfactory empirical relation is developed for the total shock‐wave attenuation.A Rayleigh‐type incompressible ``pipe''‐flow analysis applied to the experimental results overestimates the attenuation for stronger shock waves.