Spectral emergence is defined by the difference between the ambient noise level in a standardised octave band, including the particular noise in question, and the residual noise level in the same octave band, consisting of all the usual exterior and interior noises corresponding to normal occupation of the premises mentioned in the second paragraph of article R. 1336-6, in the absence of the particular noise in question.
The limit values for spectral emergence are 7 decibels in the standardised octave bands centred on 125 Hz and 250 Hz and 5 decibels in the standardised octave bands centred on 500 Hz, 1,000 Hz, 2,000 Hz and 4,000 Hz.