The following listing of hearing centers in the United States was compiled from questionnaires sent to the centers, and returned during the period of Aug. 15, 1956, to Oct. 1, 1956.
When questionnaires were not returned, the information from the previous survey was used1 and marked with an asterisk. Eighteen new centers were added to this year's listing, and nineteen formerly listed centers were dropped. Exclusion was made on the basis of inadequate equipment, dissolution of the center, or failure to reply to questionnaires since 1954.