tone-corrected perceived noise level

11.16  tone-corrected perceived noise level. Perceived noise level obtained by adding an adjustment that is related to the degree of irregularity that may occur among contiguous one-third octave band sound pressure levels of an aircraft noise. Unit, decibel (dB); abbreviations, PNLT, TPNL; symbol, L_TPN.

Annotation 1          The adjustment procedure is described in International Civil Aviation Organization, ICAO 9501, Environmental Technical Manual on the Use of Procedures in the Noise Certification of Aircraft, Third Edition, 2004.

Annotation 2          The adjustment is intended to account for the extra subjective noisiness caused by pronounced audible tones such as may be generated by airplane propellers, compressors, turbines, or fans and may vary from 0 to 6 2/3 dB.