Possible Clues:

• Sound from a forge
• Dinner bell sound
• A sound family: good start
• Worrisome mechanical sound
• Toll of a bell
• Sounds as if the century in Scotland will not be a short one
• Trolley-bell sound
• See how lenghty this is in Scotland, by the sound of it
• Noise from Scots group heading for Glasgow
• Word repeated in "The Trolley Song"