Sound Level Meter

A sound level meter (SLM) is an instrument designed to measure sound pressure level in accordance with IEC 61672-1. It consists of a microphone, preamplifier, frequency weighting networks (A, C, Z), time weighting (Fast, Slow, Impulse), and display. Class 1 meters offer the highest accuracy (±1.1 dB at 1 kHz) and are required for regulatory compliance measurements. Class 2 meters (±1.4 dB) are acceptable for survey work. Modern integrating sound level meters also measure equivalent continuous level (LAeq), peak levels, and statistical distributions (percentile levels L10, L90). For room acoustic work, analyzers with octave and third-octave band filters are needed. Building acoustic measurements per ISO 16283 require a Class 1 instrument. Manufacturers include Brüel & Kjær, NTi Audio, Larson Davis, and Svantek. Regular calibration and proper microphone orientation are essential for accurate results.