Please see the following link.
http://www.copyright.gov/docs/sound/
(third paragraph):
Although sound recordings were first given federal copyright protection in 1972, sound recordings made before February 15, 1972 remained protected under state law rather than under the federal copyright statute. As a result, there are a variety of legal regimes governing protection of pre-1972 sound recordings in the various states, and the scope of protection and of exceptions and limitations to that protection is unclear. Current law provides that pre-1972 sound recordings may remain protected under state law until February 15, 2067. After that date they will enter the public domain.
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The term of protection for sound recordings fixed prior to February 15, 1972 should be 95 years from publication or, if the work had not been published prior to the effective date of legislation federalizing protection, 120 years from fixation. However,
In no case would protection continue past February 15, 2067, and
In cases where the foregoing terms would expire before 2067, a right holder may obtain extended protection for any pre-1972 sound recording by making that recording available to the public at a reasonable price and, during a transition period of several years, notifying the Copyright Office of its intention to secure extended protection.
Welcome to the wonderful world of US copyright....