Pnc Calculator

Overview

Engineering reference data for Pnc Calculator in acoustics.

Key Formulas

Speed of Sound

$c = \sqrt{\gamma R T}$

Speed of sound in an ideal gas.

Sound Level

$L = 10 \log_{10}(I/I_0)$

Decibel level.

Wavelength

$\lambda = c / f$

Wavelength = speed / frequency.

Variables

PNC Ratings and Applications

The Preferred Noise Criterion (PNC) is used to evaluate background noise in occupied spaces by comparing measured sound pressure levels against a set of criterion curves. Each PNC curve defines a maximum allowable level in each octave band from 31.5 Hz to 8000 Hz.

A PNC rating is assigned by identifying the lowest PNC curve that lies entirely above the measured noise spectrum. Lower ratings indicate quieter, more acoustically controlled environments.

Typical Application Environments:

• PNC 15-20: Concert halls, recording studios, broadcast studios.
• PNC 25-30: Private offices, conference rooms, bedrooms.
• PNC 35-40: Open-plan offices, large private offices, living rooms.
• PNC 45-50: Retail stores, lobbies, light industrial spaces.
• PNC 55+: Workshops, mechanical rooms, industrial spaces (where speech communication is not critical).

References

• Original Source