The woman was travelling on the 7.15am Edinburgh Waverley to Glasgow Queen Street service on Monday when the incident happened.
A spokesman for British Transport Police (BTP) said: “A fellow passenger took exception to the noise and started shouting and swearing at the victim.
“It left her badly shaken and distressed.”
The offender left the train at Polmont station and was described as a woman carrying a light canvas bag.
Officers want to speak to anyone who was on the train and saw what happened.
Anyone with information is asked to call BTP on 0800 40 50 40.