By Ian Parker BBC News Online, Bristol

Despite cost implications, most bus operators welcome the move

Bath and North East Somerset Council wants to limit the number of loudspeakers "polluting" the city and could make buses install headphones.

Old, dirty tour buses could also be banned under new legislation aimed at cutting the number of tours clogging up the historic city's streets.

Currently it is very easy to set up a tour bus using an old vehicle.

There are significant tax breaks in place which means operators only need a handful of passengers to break even.

Old buses scrapped

The council is preparing its case to put to the Western area Traffic Commissioner which would allow it to impose the pollution controls.

The precise details will be subject to the commissioner's approval, but the council is looking towards the new "Euro IV" European standard.

That means only newer vehicles meeting these guidelines would be able to carry out tours, and some of the older ones could have their engines modified to comply.

Those that could not be modified, would have to be sold or scrapped.

The proposed legislation means tour operators will have to make commercial decisions as to whether they continue in the market.

More headphones

One tour operator told the BBC if legislation was introduced, then they would just "have to deal with it".

A spokeswoman for First Bus, who run commuter and tour services in the city said the company welcomed the changes.

"We are aware of the limitations of older vehicles in our fleet but have a rolling plan to replace the buses.

"Reduced emissions make Bath a better place for the residents to live in.