"Robin Mayes" wrote in message .. .

The main trouble with 'excessive volume' on P.A. systems on the Underground
is station staff have no way of altering the volume levels for different
parts of the station. A recording that is audible for a platform with a
train arriving will be booming within the ticket hall, a recording that
sounds suitable at 5am will sound too quiet at 5pm. There is no way for the
staff who are doing the recording to know that the volume will be too loud,
as over the years P.A. zones have had the volumes turned up or down by
engineers so it's a case of trial and error, sadly.

Microphone in each zone to measure the ambient noise level, and alter
the PA level accordingly? Shouldn't be that expensive, and would
alter the PA level dynamically as the ambient noise level changes.