A song played on the radio encompasses two separate copyrights, one for the musical composition and one for the sound recording.
The standard copyright symbol is © and applies to the author of a composition, the song and its lyrics. Copyrights generally apply to the life of the author (or last survivor of a team) plus 70 years, with some variations. This legal protection may also extend artwork and photographic materials used in the creation of packaging.
The symbol for copyrighted sound recordings is ℗. The p stands for phonogram, a legal term applied to the master recording of music, spoken words, or sounds on LPs, audiotapes, cassette tapes, compact discs, etc. A specific sound recording copyright does not apply to any other rendition or version, even if performed by the same artist(s). It is usually noted in the same way as the more familiar copyright symbol (example: ℗ 1987 Name of Owner). The author of the sound recording is typically the performer(s), the record producer, or both.
Answers to specific individual questions should be obtained from qualified legal counsel.