There will usually be more than one copyright associated with a work such as a song. If you are the composer of the music you will be the author of the musical work and will have copyright in that music. The lyrics of the song are protected separately by copyright as a literary work and will usually be owned by the person who wrote them.
The term of protection for an original musical and literary work is the creator's life plus 70 years from the end of the year in which he/she dies. In September 2011 the European Union approved a directive which includes measures to align the term of protection for the music and lyrics in a musical composition.
Currently, if a work is recorded then copyright in this sound recording lasts for 50 years from the end of the year in which it was made or, if published in this time, 50 years from the end of the year of publication. If the recording is not published during that 50 year period, but it is played in public or communicated to the public during that period, then copyright will last for 50 years from when this happens. In September 2011 the European Union approved a directive which will extend that period for sound recordings and performers' rights in sound recordings to 70 years.
Sound recordings do not have to be original but they will not be new copyright works if they have been merely copied from existing sound recordings.
Sound recordings may also contain performers' rights.