Singin' in Cincinnati
With the coming World Choir Games to Cincinnati and City Council's promoting the town as, "Cincinnati - the city that sings", it seems to me that loosening up the regulations on group singing in the Queen City might be in order.
To sing as an ensemble on Cincinnati streets ain't all that easy. You can find it all in Section 909-3 Loud Noise.
First thing you have to do is decide where you want to perform & find out the zoning designation that applies to that area. You will need a tape measure & sound meter. Fortunately, Hamilton County has a handy whiz bang map with all sorts of dynamic graphic clutter to find the zoning designations. You can find out what the arcane initials mean here. Then, going back to Section 909-3 Loud Noise, you can check the tables to see when & how loud you can perform. The Sunday to Wednesday tables are identical to the Thursday tables except, apparently, public music performances are not allowed in MA (Manufacturing Agriculture) areas on Thursdays.

If the area you desire is PD, HS, UD, IDC, or HD, you need to ask Department of City Planning and Buildings.
The acceptable decibel levels for various zoning designations & times are listed in the tables. What's interesting here is that, at no time can one perform over 75db even though the generally accepted sound of traffic is around 80db meaning the sound of traffic is more acceptable to our society than music nd it is illegal to be heard over the cars that, presumably, would be on the street.
After the tables at Section 909-3 Loud Noise we get to the best part.

The performance of one or two street musicians on unamplified musical instruments between the hours of 11:30 a.m. and 1:00 p.m. or between the hours of 5:30 p.m. and 10:00 p.m., for no more than a single period of 90 consecutive minutes in the vicinity of a single location and not closer than any of the following: a) 20 feet to a pedestrian crosswalk; b) 20 feet to a street vendor; and c) 100 feet to an open market as such are defined in section 845-3 CMC, shall not constitute a violation of this section.

So, your barbershop quartet can just go to hell. Also, if you want piano accompionment, you will have to haul your upright down to where you want to play (as long as it's not an MA designation on a Thursday) & play because your midi controller, laptop & Crate are criminal in Cincinnati - the city that sings - but only acapella and not between 1-5:30PM.

Cincinnati really needs to move into the 21st late 20th century on this issue and with the attention to music coming this summer, now is a great time to address it. The definition of decibel levels & how they are measured is a good first step but the limit to 2 people was brought about in the 90s to accommodate a particular issue in a reactionary way and has never been addressed in a rational, comprehensive way. The ban on amplification is just backwards & frankly kinda classist.