An interdimensional sound creature attacked Paris in December 1946.
The Ninth Doctor theorised that it fell through a rift in the Time Vortex from another dimension that was full of dark and warped sounds. It was attracted to loud noise and, although mostly invisible, could "eat" noises, warping space and killing those around it. It could be briefly driven away by white noise but eventually grew in power to resist it.
The creature found itself drawn to Artie Berger due to his musicality and feelings of grief and indiscriminately killed those around him in its efforts to feed off him. Eventually, the Doctor was able to trap it in a bottle after using it as an echo chamber and he promised to dispose of it in the Vortex. (AUDIO: Fright Motif [+]Loading...["Fright Motif (audio story)"])