In a vote of 6-1, the Walla Walla City Council banned "unamplified" human voices from 10 PM to 7 AM on weeknights and 11 PM to 9 AM at their recent council meeting.

According to the ban, human voices can't exceed 45 decibels during the hours designated. The equivalent is between a babbling brook or light traffic.

Here are details on the ordinance from the Walla Walla Union Bulletin

Mayor Barbara Clark brought the idea of restricting unamplified human voices at an Oct. 10 City Council meeting. Clark said her neighborhood had about half a dozen parties at different residences within a few months, some of them going until 3 a.m.

“There was a lot of loud and obnoxious, drunken sounds that were disruptive,” she said at that meeting.

Before the change, unamplified human voices were not subject to noise ordinances, falling under the same category as natural phenomenon. But Clark argued people were still capable of creating a nuisance without speakers or other amplifying equipment.

“I don’t think neighborhoods should be subjected to that kind of loud noise based on the fact that people aren’t using sound equipment of some kind,” Clark said.

I'm not sure the details on enforcement of the ordinance but it seems that there will be a lot of gray area for law enforcement to figure out. You can check out more details on the ordinance here