Is there any protection after copyright expires?

If a literary, dramatic, musical or artistic work or film whose copyright has expired has never been made available to the public, it may be protected by publication right when it is made available to the public for the first time. Publication right is granted automatically to the first person to make a relevant work or film available to the public within the European Economic Association (EEA), it expires 25 years from the end of the year in which the work is made available, and gives rights broadly similar to those given by copyright.

Otherwise, a work in the public domain can be used by anyone in the same ways that the right holder was entitled to do exclusively whilst it was protected by copyright.  It is important to remember that whilst a sound recording may, after 50 years, be out of copyright,  its underlying works e.g. lyrics or music, will probably still be protected so you will need permission from the owners of these.