The recorder was a musical instrument.
The Second Doctor frequently played his recorder, especially when he needed to think deeply about something. (TV: The Power of the Daleks, et al.)
He also on occasion used it as a telescope. (TV: The Wheel in Space, The Invasion, The War Games)
Shortly after his regeneration, the Fifth Doctor found a recorder lying around in the TARDIS and attempted to play it, but he quickly decided that it was just not his style. (TV: Castrovalva)
At some point before his eleventh incarnation, the Doctor played the recorder at a Roseland Ballroom concert with Ella Fitzgerald; it did not end well. (PROSE: Night of the Humans)
The Eleventh Doctor carried a recorder and played it. (PROSE: Shroud of Sorrow)
On Friday evenings, Jacqui would usually sit around the fire and play her recorder at the peace camp. (PROSE: Return of the Living Dad)
A lassimater was part flute, part recorder and part didgeridoo, and made the most beautiful music in the universe. (PROSE: Most Beautiful Music)