Volume just increases at will

Ever since I installed ubuntu 14.04, my master volume is just increasing by a number of ticks. This process recurs but it is not at regular intervals. I have tried checking if it is related to any other activity e.g keystrokes or even the mouse but it is not. At times it may stay high at times and then returns itself to a lower level after some time. I only listen to music via Youtube and Rhythmbox. What could be the issue with this computer?
