Sound Radiation Modes of a Tire on a Reflecting Surface

The radiation characteristics of a three-dimensional tire model in contact with a reflecting surface and enclosed by a hemispherical recovery surface was studied in this paper by using acoustic radiation modes and by comparing free-space radiation. The sound power resulting from the structural wave propagation created by a single drive point on the tire center line was investigated. It was found that the second radiation mode above 700 Hz is principally responsible for the horn effect in the presence of reflecting surface, and that it results in significant amplification of sound from the contact patch area. The significance of the fast, longitudinal wave mode propagating through the treadband was confirmed by the large contribution of the modified ring radiation mode to the radiated sound power at the tire’s ring frequency.