ABSTRACT
It is important to note that the spectrum level of the noise as presented in the equation above is not the same as the octave band or one-third octave band level measured using a spectrum analyzer. Spectrum level refers to the level per Hz or the level that would be measured if the noise were analyzed using a 1-Hz wide filter. If we assume that the noise is flat within the bandwidth of a one-third octave band filter, for example, then the spectrum level can be estimated using the following equation:
10BL/10 L
S = 10 Log ( )BW
where L S is the spectrum level of the noise within the one-third
is the bandwidth of the one-third octave band filter, calculated by multiplying the center frequency (f
the filter by 0.232 (Beranek 1988), and BL is the noise level measured in the one-third octave band in question.
