Here's a web-site I found that has the code for Mount Vernon
http://www.e-codes.generalcode.com/c...t=ws&cb=0742_A
However, I still couldn't find an ordinance by the numbers you gave me.
If your ticket is for 178-4(B)(7), I'd go for a void for vagueness defense because that section alone does not set out any objective standard for measurement.
However, objective decibel-based standards are set out in 178-4.3(B) and 178-4.4 so they should have noted a decibel level on the ticket as measured at a distance of 50 feet from the center lane of which the vehicle is traveling.
If there's no recorded decibel level on the ticket, you should be fine.
Just my .02; not legal advice.