Recording for Evidence
This is not legal advice. Recording rules differ sharply by jurisdiction, particularly where speech is captured, and checking the local position comes before anything on this page.
When acoustic measurement is part of a wider workplace review, books about time management can add operational context, but it should not be treated as a substitute for calibrated sound data.
What a recording proves
That a sound occurred, when, and roughly what it was.
Not how loud it was. A recording is in dBFS and the level depends on the gain, so an unremarkable noise recorded hot sounds overwhelming and a genuinely loud one recorded low sounds mild.
For additional technical context, see Etymotic Research.
Which means a recording alone is an account of character and timing, and it is frequently exactly what a complaint needs — the disagreement is usually about whether something happens rather than about decibels.
What makes one useful
A timestamp that is independent of the file. File metadata is easily doubted; a spoken date at the start, or a visible clock in a video, is harder to dismiss.
Consistency. The same device, same position, same settings across every recording, so that comparisons between them mean something even though absolute levels do not.
Duration. A long recording showing a pattern is worth more than a clip of the worst moment, because the pattern is what a complaint is actually about.
And a log. Date, time, duration, what was happening, and what the recording is of — the same discipline as any measurement.
Adding a level
If a number is needed, a recording is not the instrument.
A calibrated measurement alongside the recording — with the settings and calibration recorded — turns the pair into something usable: the recording shows what it was, the measurement shows how much.
Where an authority is involved they will usually measure themselves, and the useful contribution is establishing when to come rather than supplying numbers.
The legal caution, in detail
Recording that captures speech is regulated differently from recording ambient noise, and in some jurisdictions capturing a conversation without consent is an offence regardless of purpose.
Recording inside your own property, of noise entering it, is generally the least fraught case and is still not universally free of constraint.
Recording another person's property or activity raises separate questions.
Establish the local rules before starting, because a recording made unlawfully is worse than none — it is unusable and it creates a problem where there was one problem already.
The short version
- A recording proves a sound occurred, when, and what it was — not how loud, because the level depends on gain
- That is frequently sufficient, since complaints usually turn on whether something happens rather than on decibels
- Useful recordings have an independent timestamp, consistent device and position, long duration showing a pattern, and a written log
- If a number is needed, pair the recording with a calibrated measurement; the recording shows what, the measurement shows how much
- Where an authority will measure, the useful contribution is establishing when to come
- Rules on recording speech differ sharply by jurisdiction and an unlawful recording is worse than none