How to Work Out Whether a Noise Complaint Is Actionable

Why this matters

A shop gets a noise complaint, drives out with a meter, takes a reading, and hands over a number that answers nothing. The number is not wrong. It is unusable, because a level only means something against a named instrument, and every instrument that could make a complaint actionable specifies a different quantity, a different position, a different time basis and a different remedy. There is no conversion between them. A dosimetry result on a technician cannot be turned into a property-line figure and a property-line figure cannot be turned into an exposure. So the first move on any noise complaint is not a measurement, it is naming which instrument governs, and it is entirely possible for two to govern the same machine at once, each demanding its own measurement on its own basis.

Step 1: identify the complainant, because the complainant names the instrument

Three families, and who is complaining places you in one of them almost immediately.

Skip this step and you lose the ability to use anything you measured. A visit that produced readings on the wrong basis is a visit that has to be repeated, and on a night-time community complaint that means another night.

Step 2: get the instrument itself, in the version that binds

For the occupational family, the CFR text is the instrument and it is federal. For the community family, get the ordinance as adopted and amended by that specific jurisdiction, from the municipal code or the clerk's office, and note that there is no federal community noise limit, so a number somebody quotes from another town is not evidence about this one. For the private family, get the actual clause out of the actual lease or specification, not a description of it.

Skip this and you measure against a remembered rule. The ordinance detail that most often surprises people is the position, and it is not usually where the complainant is standing.

Step 3: write the measurement basis down before the meter comes out

From the instrument, extract and write: the quantity (sound pressure level, referenced to 20 micropascals), the weighting (A, C or unweighted), the bandwidth (overall or per band), the time basis (fast, slow, equivalent-continuous over a stated duration, or peak), the position and height, the time-of-day period, any tonal or impulse provision, and whether the limit applies to the total measured level or only to the level attributable to the source. That last one changes the arithmetic and it is stated in the ordinance rather than assumed.

Skip this and you produce a figure that cannot be compared with the limit. A 5-minute equivalent-continuous level and a fast-response maximum are different quantities even at the same position with the same weighting.

Step 4: establish the residual on the same basis, and apply the margin gate

Take the background with the source off and nothing else changed, on the identical basis and at the identical position, then apply the margin gate: 10 dB or more of margin means the combined reading is the source within a few tenths and the correction is declined and said to be declined; 3 to 10 dB means a stated correction comes off; under 3 dB means no source level at all, only an upper bound written with one inequality. The sibling procedure card owns that table and its correction values.

Skip this and you will report the neighbourhood back to the neighbourhood as if it were your customer's machine.

Step 5: measure on that basis, and if two instruments govern, take two sets

Calibrate before and after the whole set and record both readings, because a drift check that fails voids the set rather than adjusting it. Where an employee exposure and a community limit both apply, that is two separate campaigns with two instruments, two positions and two time bases. Do not convert between them. There is no valid arithmetic that turns one into the other.

Step 6: compute the rated level where the instrument imposes a penalty

Some ordinances add a penalty for a tone or for impulsive character before the comparison with the limit. That penalty is an addition producing a different quantity, a rated level, and the measured level stays on the record unchanged beside it. The tonal card owns the trigger test and the size; what to carry here is that the number you compare with a limit may not be the number your meter displayed.

Step 7: write the finding with the instrument named in the same sentence as the number

"51.7 dB A-weighted, 10-minute equivalent-continuous, slow response, re 20 micropascals, at the receiving property line at the position marked on the sketch, against a night-period limit of 50 dB A-weighted on the same basis in the ordinance as adopted." A number without its instrument and its basis is not a finding.

Step 8: route the remedy to the family that owns it

The occupational family's remedy is the hierarchy the standard states: feasible engineering and administrative controls first, hearing protection alongside, plus the program elements that trigger at the action level. The community family's remedy is abatement to the limit at the stated position, which is an engineering problem. The private family's remedy is contractual and the question of what a clause obliges anybody to do goes to the reader's own attorney rather than being settled with a meter.

Working the site without adding a hazard

Set and secure a ladder under 29 CFR 1910.23 and keep three points of contact on it, and where the measurement position is on a roof or near an unprotected edge, fall protection under 29 CFR 1910.28 applies for the whole time you are up there, including the part where you are kneeling to read a display. Every reading taken beside running equipment is taken with all guards in place as 29 CFR 1910.212 requires and from outside the rotating plane, and where your own exposure at that position reaches the action level for the time you will be there, wear the protection your program specifies. A property-line measurement is taken from your client's property, from the complainant's property with their permission, or from public right of way; where access is unclear, that is a legal question and not a judgement call to make standing at a fence line.

Worked case: one machine, two instruments, two different answers

A rooftop condensing unit at a small commercial building. In the same week, the building's own maintenance technician reported the roof as loud, and a resident across the property line filed a night-time complaint.

Instrument one, occupational. Personal dosimetry on the technician's hearing zone across the full workday, A-weighted, slow response, using the 5 dB exchange rate the standard specifies. The workday came out as 6 hours of roof work averaging 88 dB A-weighted and 2 hours of other duties averaging 75 dB A-weighted.

• Permitted duration at 88 dB A-weighted is 8 divided by 2 raised to the power of 88 minus 90 over 5, which is 10.56 hours.
• Dose from that segment is 6 over 10.56, which is 0.568, or 56.8 percent.
• The 2 hours at 75 dB A-weighted contribute nothing, because the dose calculation counts levels from 80 dB A-weighted upward.
• Equivalent 8-hour time-weighted average is 16.61 times the base-ten logarithm of 0.568, plus 90, which is 85.9 dB A-weighted.

That is above the 85 dB A-weighted action level, so the hearing conservation program elements apply to this technician's employer. Note what the arithmetic did: an exposure lasting only six hours, at a level two decibels under the permissible exposure limit, still crossed the action level, and nobody would have guessed that from the 88 dB A-weighted reading alone.

Instrument two, community. The ordinance as adopted by the jurisdiction the receiving property sits in sets a night-period limit of 50 dB A-weighted, as a 10-minute equivalent-continuous level, slow response, at the receiving property line, applied to the level attributable to the source.

• Combined, unit running: 52.4 dB A-weighted on that basis at the marked position.
• Background, unit off, nothing else changed, same position and basis: 44.0 dB A-weighted.
• Margin is 8.4 dB, which sits in the 3-to-10 zone, so the correction from the sibling table at that margin is 0.7 dB.
• Source contribution: 52.4 minus 0.7, which is 51.7 dB A-weighted.
• Against a 50 dB A-weighted limit, the site exceeds by 1.7 dB.

What the two results share: nothing. Different quantity basis, different position, different height, different duration, different time of day, different enforcer and different remedy. The 85.9 dB A-weighted time-weighted average says nothing about the property line and the 51.7 dB A-weighted property-line figure says nothing about the technician. Both are true and both are actionable, under separate instruments, and a shop that took one reading and called it "the noise level" would have missed one of them entirely.

Sibling-rule check. Every figure carries quantity, weighting, bandwidth, time basis, reference, position and duration. The background margin gate is applied to the community figure using the zones and correction values the sibling procedure states; the occupational figure is a time-weighted average from dosimetry rather than a corrected sound pressure level, so no background correction is applied to it and none is implied. The 5 dB exchange rate and the 80 dB A-weighted cutoff are the standard's own, stated with the standard. No conversion between instruments is performed anywhere, the tonal provision is referred to its owning card, and no rounding runs in the direction that flatters the site.

How to verify you got the triage right

Ask three questions of your own report before it goes out. Can a reader tell, from the sentence containing each number, which instrument that number is compared against? Would that number still be valid if the complainant changed, and if not, is the report explicit about which complainant it serves? And is any number in the report produced by converting a measurement taken on one basis into another? A yes to the third is the failure this procedure exists to prevent, and it is easiest to catch by reading the report backwards, from the conclusion to the readings, checking that each figure carries the basis it was taken on.

References

• 29 CFR 1910.95, occupational noise exposure in general industry, including its Appendix A dose and time-weighted-average computation and the 5 dB exchange rate
• 29 CFR 1926.52, occupational noise exposure in construction, where the work falls under that Part instead
• 29 CFR 1910.23 and 29 CFR 1910.28, ladders and fall protection, for roof and elevated measurement positions
• The noise ordinance as adopted and amended by the jurisdiction the receiving property sits in, which owns the limit, the position, the time basis and any penalty; there is no federal community noise limit
• See related: How to Add and Subtract Noise Levels Correctly; What a Community Noise Limit Is Usually Written Against; What Hearing Conservation Actually Requires