NTi has added individual under-range indicators for both C- and Z-weighted sound levels within its XL2 Sound Level Meter.
The XL2 is designed to support high measurement accuracy with under-range indicators. These inform users, during low level measurements, that an alternative microphone with lower noise floor or higher sensitivity should be used.
In the past the XL2 indicated when readings were below the linear measurement range for the A-weighted level in accordance with the standard IEC 61672. Now the instrument displays an under-range status also for individual levels with C or Z frequency weighting. Should any sound level be detected as under-range, then the XL2 marks this level with the new symbol “<“, e.g. “LZeq < 23 dB“.