“Pure tone” means any sound which can be judged as audible as a single pitch or a set of single pitches by the noise control office. For the purpose of this chapter, a pure tone shall exist if the one-third octave band sound pressure level in the band with the tone exceeds the arithmetic average of the sound pressure levels of the two contiguous one-third octave bands by five dB for center frequencies of five hundred Hz and above and by eight dB for center frequencies between one hundred sixty and four hundred Hz and by fifteen dB for center frequencies less than or equal to one hundred twenty-five Hz. (Ord. 90-7 (part), 1990)