The (British) Noise Abatement Society has suggested using broadband noise alarms rather than the more piercing single-tone beeps that carry for miles. This would improve the quality of life for people (like mself) who live near a building site where the beeping continues twelve hours a day, six days a week. This solution doesn't compromise safety, in fact it probably improves it since the noise is highly directional.
http://www.noiseabatementsociety.com/tcms/view.do?page=304
It's sad there are a lot of nutters writing about tits on this page. I love tits and have many in my garden.