The Lexington Fire Department is now broadcasting live on the internet!  It is provided through the services of www.RADIOREFERENCE.COM.  This is the former ScanAmerica.us website.  A direct link to the Audio Page is http://www.radioreference.com/apps/audio.  Click on the state of MA. and then click on the Middlesex County section.  Follow the websites instructions on how to use the service for the best results.