Iowa Admin. Code r. 571-62.12
Creating or sustaining any unreasonable noise in any portion of all state forests is prohibited at all times. The nature and purpose of a person's conduct, the impact on other area users, the time of day, location, and other factors which would govern the conduct of a reasonable, prudent person under the circumstances shall be used to determine whether the noise is unreasonable. Unreasonable noise shall include the operation or utilization of motorized equipment or machinery such as an electric generator, motor vehicle, or motorized toy; or audio device such as a radio, television set, tape deck, public address system, or musical instrument; or other device. Between the hours of 10:30 p.m. and 6 a.m., noise which can be heard at a distance of 120 feet or three campsites shall be considered unreasonable.
Iowa Admin. Code r. 571-62.12