The volume (dBA) and the length of exposure to the sound will tell you how harmful the noise is. According to the National Institute for Occupational Safety and Health, the maximum exposure time at 85 dBA is eight hours. Generally, expect older machines to be noisier. AND k Maximum sound levels may not exceed 80 decibels between the hours of 11:00 pm and 7:00 am within 50 feet of a residential Normal conversational levels are in the 60-65 dBA range, and ambient noise levels greater than 65 dBA can interrupt conversations. Statutory nuisance legislation is routinely implemented and enforced by local authorities. The outdoor level - L dn - in a wilderness areas may occur as low as 30 - 40 dBA compared to 85-90 dBA in a urban areas. k Maximum sound levels may not exceed 80 decibels when measured at a distance of 35 feet or more from the compacting unit of the vehicle when it is not engaged in compacting a load of refuse. NR Curves are depicted in the graphic below. Additionally, there is a category called 'silent zone' which includes areas that lie within 100 meters of the premises of schools, colleges, hospitals and courts. Most urban dwellers lives in areas of L dn more than 48 dBA . The NIOSH Sound Level Meter App is a tool to measure sound levels in the workplace and provide noise exposure parameters to help reduce occupational noise-induced hearing loss. Sounds must also be specified in terms of frequency or pitch. In other words, sound intensity doubles every 3 dB. Investigating officers will sometimes use sound level meters to help them assess nuisance but for most cases… Noise Criterion [NC] Noise Criterion was developed in the 1950s and was most often used in the United States to depict the acceptable range of background noise in a space. Maximum Permitted Noise Level Contrary to popular belief there is no maximum permitted noise level that needs to be exceeded for noise to be categorised as a 'nuisance'. The amount of noise depends on the age of the machine, the type of air conditioner and its condition. But 93 dB is still twice as much noise as 90 dB. In general, the louder the noise, the less time required before hearing loss will occur. It is common that Day-Night sound levels - Ldn - in different areas may vary a range of 50 dB. Hearing protection should be used for any level over 85 dB and double protection for any level over 105 dB. Each curve depicts the acceptable dB levels across a range of frequencies between 31.5 Hz and 8,000 Hz (8 kHz). In commercial areas, it is 65 dB and 55 dB while in residential areas it is 55 dB and 45 dB during daytime and night respectively. Noise levels typically attenuate (or drop off) at a rate of 6 dB per doubling of distance from point sources such as industrial machinery. Outdoor air conditioners are often as loud as 80 or 90 decibels. Continued exposure to noise above 85 dBA (adjusted decibels) over time will cause hearing loss. Air conditioners can contribute a great deal to the noise level in your house.