Z-Weighting (dBZ)

Z-weighting was formalized in the 2002 revision of IEC 61672 to standardize what was previously called "Linear" or "Flat" weighting. Different manufacturers had inconsistent definitions of "linear" — some applied no filtering, others had bandwidth limits — creating measurement ambiguity. Z-weighting specifies a nominally flat response from 10 Hz to 20 kHz within specified tolerances (±1.5 dB for Class 1, ±2.0 dB for Class 2). The primary use of Z-weighting is in research and calibration where the raw, unfiltered sound pressure level is needed. It is also used in noise source identification, where frequency-dependent weighting could mask the true spectral character of a source. Building acoustics measurements (ISO 16283) often use Z-weighted levels in individual frequency bands before applying corrections. Z-weighting provides the baseline from which A- and C-weighted values can be computed. If you have Z-weighted 1/3-octave band data, you can calculate the A-weighted or C-weighted overall level by applying the respective correction factors to each band and summing energetically. This is more accurate than applying a single broadband weighting filter. In practice, the difference between dBZ and dBC is small across most of the audio range (both are nearly flat from 31.5 Hz to 8 kHz), but they diverge at the frequency extremes. For most live sound and noise monitoring applications, either C- or Z-weighting captures the full-bandwidth energy content. SonaVyx supports all three weightings (A, C, Z) simultaneously, allowing real-time comparison of weighted values and immediate computation of the diagnostic C-A difference.