Does anyone know a poem about musicians tapping their foot in time as they play?

There is a short poem making gentle fun of a group of musicians - a quartet perhaps - playing together. Suddenly one player spots another player's foot tapping wildly to the beat and quite out of sync. The poem reflects the original player's horror as he doubts the pulse he's beating to, and almost creates musical havoc between the group of players. The poem's just so true to life, and very funny. It might possibly be called ''The Foot''