This provision is a "subjective immission" control. It is designed to limit the noise disturbance between living units as defined by an enforcement official. One criterion used to evaluate that disturbance is use of "plainly audible" but at the location of the listener instead of at a specific distance. However, Charlotte, NC (Sec. 15-69) limits indoor levels to 55 dB(A) between 9am to 9pm and 5 dB less at other times, but only from sound reproducing devices. Salt Lake Valley Health Department (Chapter 4), Minneapolis, MN (Chapter 389), and Albuquerque, NM (Article 9) use levels to existing ambient to define a violation. Albuquerque NM and Omaha, NE (Chapter 17) require that intruding sounds not be audible. Burlington, VT (Chapter 18) requires that renters be supplied with the city noise ordinance.