Guide · HPZ visualisation - Hearing Protection Zone visualisation

Why drawing the boundary matters

A sentence like “the area around the press line exceeds 85 dB(A)” is correct but hard to act on — where, exactly, does “around” end? A boundary derived from the measured contour and traced onto your own floor plan answers that precisely: everyone can see exactly where signage, screening, and hearing protection rules need to apply, and where they don’t.

How the boundary is derived

The same Class 1 survey measurements that feed your written Noise at Work Assessment are interpolated into a continuous noise surface across the floor. Wherever that surface crosses 85 dB(A), the map draws the Hearing Protection Zone boundary — not a hand-drawn estimate, but the actual measured contour at the regulatory trigger. See 3D noise mapping explained for how the underlying survey and modes work.

What you can do with it

• Site signage — know precisely where Hearing Protection Zone signage needs to go, instead of guessing a margin around a machine.
• Briefing staff — a picture staff can actually read, rather than a clause in a PDF nobody opens.
• Planning a change — in Predicted mode, see how a new screen or enclosure would move the boundary before it’s built.
• Evidencing control — a defensible visual record for insurers, auditors, or an HSE inspector, sitting alongside the written assessment.

See a real worked example of HPZ boundaries drawn on a floor in our illustrative press-shop map, or more generally in Hearing Protection Zones explained.