DutyNode: a free low-frequency noise checker for people near data centres
DutyNode lets people living near data centres check whether the hum they hear is the kind of low-frequency noise that ordinary decibel readings miss, using published screening methods, in under a minute and without signing up.
Run a noise check on DutyNode → Talk to me about a tool like this
The problem
Most noise limits are written in A-weighted decibels (dBA). A-weighting discounts low frequencies, which is exactly where the steady rumble of cooling fans, chillers and backup generators sits. A site can meet its dBA limit while residents still can't sleep.
Published methods for screening low-frequency noise exist, but they are spread across technical reports that residents, and often their councils, have never seen.
What I built
- A free noise checker with two screens: a quick one that needs only an A-weighted and a C-weighted reading, and a full one for one-third-octave band readings.
- A sourced case tracker of data-centre noise lawsuits, notices and rules, each with its source, and a free weekly email when a new case appears.
- A USD 39 evidence report that sets out a household's readings against the published methods, for a complaint to a council or an operator.
How it works
The quick screen compares the C-weighted and A-weighted levels of the same sound. The WHO Guidelines for Community Noise (1999) recommend a frequency analysis when the difference exceeds 10 dB. Leventhall's review for the UK Government's DEFRA (2003) reports a 6 dB adjustment above 15 dB, and describes a gap over 20 dB as the potential for a low-frequency noise problem.
The full screen takes one-third-octave Leq readings from 10 to 160 Hz, measured indoors where the noise is heard, and compares them band by band with the reference curve in Moorhouse, Waddington and Adams, Procedure for the assessment of low frequency noise complaints (University of Salford for DEFRA, NANR45, 2005; revised 2011), including its 5 dB relaxations for daytime-only and steady noise.
Every result cites its source, rejects implausible readings, and is labelled as a screen, not a compliance determination.
Built with
Python and FastAPI, PostgreSQL (Supabase), Stripe, Resend, hosted on Render. Built from idea to a live product with payments and email in about a day, in October 2026.
Questions
What is DutyNode?
A free low-frequency noise checker for people living near data centres, at dutynode.com, with a sourced tracker of data-centre noise cases and a USD 39 evidence report.
Who built DutyNode?
Richard G. Prouse. DutyNode is a trading name of Richard G. Prouse, Auckland, New Zealand.
Is a DutyNode result a legal finding?
No. It is a screen against published methods. A formal assessment needs a qualified acoustician.
Need something like this for your organisation? I build checkers, trackers, assessments and reports at a fixed price. Book a free 30-minute call.
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