Number of service requests to NYC’s 311 from 2004 to 2017: 26.99 million
Increasing probability noise not found, 2004 to 2017

When you call in a noise complaint, there is a probability that the city agency handling the complaint could not find it. Whatever the reason, when you have a high proportion of ‘not found’s, time and money is being wasted, starting with the person calling in the complaint, the person at 311 taking the complaint (if it is over the phone), and various people in various agencies who end up actually processing them. There could be innocuous reasons – maybe the person or entity making the noise has moved on. Or, they have a permit to make noise and it is, therefore, not a violation. Or, there could be less innocuous reasons, including corruption.  Or, the complaint intake design is flawed and 311 is taking complaints for things the city or the agency does not have a remedy or the will to remedy, or both.

The ‘not found’ notations:

Noise complaints to NYC’s 311, 2010 to 2017: circumestances in which noise was not found
The Department of Environmental Protection did not observe a violation of the New York City Air/Noise Code at the time of inspection and could not issue a notice of violation. If the problem still exists, please call 311 and file a new complaint. If you are outside of New York City, please call (212) NEW-YORK (212-639-9675).
The Department of Sanitation investigated this complaint and found no condition at the location.
The Police Department responded to the complaint and with the information available observed no evidence of the violation at that time.
The Police Department responded and upon arrival those responsible for the condition were gone.
The Department of Environment Protection inspected your complaint but could not find the problem you reported. If the condition persists, please call 311 (or 212-639-9675 if calling from a non-New York City area code) with more detailed information to submit a new complaint.

311 data from NYC Open Data downloaded at various times. As of Feb 5, 2018, 27 million rows, 52 variables till 2009, 53 variables from 2010. Parsed using R v3.4.3 in RStudio v1..1.423