You can use your cursor to view specific decibel (dB) levels and scroll back 24 hours, or click on the date display to view a different day. You can also click on the colored A, C, and Z dB “weighting” icons to see how they compare. For more info on weightings, see below.
The graph above shows sound-level data collected every minute by the Noise Project’s second Providence noise monitor, which was deployed in Fall 2025. The dark horizontal line is the city’s residential sound-level limit, which is 65 dB from 7:00 a.m. to 10:00 p.m. and 55 dB from 10:00 p.m. to 7:00 a.m.
The monitor is located on the east side of the city, and designated as “Bronzaft” in honor of pioneering environmental psychologist and researcher Dr. Arline Bronzaft, who advocated to reduce excessive and unhealthy noise in NY City and other urban areas.1
It is part of a planned city-wide network of sound monitors, designed to ascertain both baseline sound levels and daily / weekly / seasonal noise trends around Providence. The goal is to: 1) identify areas where and when residents face the most persistent exposure to unhealthy noise, and thus where the city should focus its abatement efforts, and 2) determine how effective those efforts actually are.
All three colored lines above represent the same sound data, but two are “weighted” (i.e., filtered) to focus on certain frequency ranges. The green line is called “A-weighting,” which emphasizes the mid-range frequencies corresponding to the human voice — by excluding most of the lower-range “bass” data.
By contrast, the orange line is “C-weighted” data, which retains far more of the low-frequency bass that comprises most of the excessive and unhealthy noise in Providence. And the blue line is called “Z-weighted” data, but is actually unweighted (i.e., “raw” sound data with no weighting).
Like most U.S. municipalities, Providence uses A-weighted sound-measurement data that, as the graph above demonstrates, usually depicts decibel levels as being significantly lower than either C-weighted or unweighted data, and thus inaccurately represents actual noise levels in the city.
For that reason, the Noise Project supports the use of C-weighting rather than A-weighting. For more information on sound weighting — including a visual depiction of what the different weightings capture — and the exponential decibel scale, visit our “How Sound is Measured” page.
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1 Dr. Bronzaft was especially concerned with how excessive noise levels affect children, and particularly their academic achievement — an issue that is largely ignored by Providence’s educational establishment. Her pioneering research showed that it directly impacted students’ test scores, which rebounded after ambient (outside) noise was reduced.