Possible Clues:

• Loudspeaker system
• Public address system
• Public-address system
• Antony disorganised for public address
• Public address makes travel start to get irritating
• It will infuriate you after the short start of 11 across, by the sound of it
• Sound amplification system
• Its address will infuriate one at last
• Sound-reproducing and amplifying system
• Pester, after time, with amplifying system