Low-Frequency Noise is underestimated by dBA. After 80 years, an LFN descriptor for rating annoyance is necessary
The dBA was defined in 1936 to measure low levels up to 55 dB; the oldest sound level meters included two panel switches: one for sound pressure and the other for frequency weighting. It became easier to measure just the dBA in late 60´s, but this was not the best decision since low-frequency noise and infrasound are underestimated by dBA weighting. WHO recommends the use of dBC-dBA and suggests that when this difference is greater than 10 dB, an analysis should be applied. For more than 80 years, the common worldwide laws against noise have forced us ‘to feel the noise in dBA levels,’ which is not true because our body ‘senses’ the whole flat frequency bandwidth. Few countries have legislation on how to assess ILFN levels. This Article discusses the necessity to create a paradigm for LFN measurement (based on ISO 1996), in order to ‘retire’ the dBA noise descriptor.