The International Congresses on Acoustics have been organized every 3 years. The first of these Congresses was held in Delft in 1953.
The Proceedings of these Congresses can often be found in libraries. Sometimes the Proceedings have been presented within the permanent framework provided by the archival journal system. More often they have been published independently. Descriptions of the Proceedings of past Congresses (1953-1986) and, where possible, addresses to which inquiries and purchase orders can be directed, have been published in the J. Acoust. Soc. Am. Vol. 86, pp 1192-1193 (1989).
The older Proceedings may be more difficult to locate. As a last approach, you will find them below in a scanned format. Please be aware that the pdf files are quite large and download times may be long. Additionally, through the efforts of Dipl.-Ing. Thore Oltersdorf, these files have been run through an OCR process to produce text-searchable versions.