Peter J. Westervelt
Dept. of Phys., Brown Univ., Providence, RI 02912
On page 1982 of their article, Berntson et al. [J. Acoust. Soc. Am. 86, 1968 (1989)] criticized virtually all experimental results on the scattering of sound by sound. In addition they gave their necessary conditions for this scattering to be observed. These conditions were fulfilled in a recent experiment [R. Roy and J. Wu, in Proceedings of the 13th ISNA, edited by H. Hob(ae ligature)k (Elsevier Science, London, 1993)] where no scattered sound was obtained in spite of the fact that the minimum detectable signal level was of the order of 50 dB below Ingard and Pridmore---Brown's theoretical predictions. The one-dimensional treatment given in the previous abstract to two space-time dimensions will be discussed further.