Frye FONIX 7000 - Manual (Page 49)

General Operation
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Chirp Composite signal is the standard composite signal used on the FP40 and
FP35 portable hearing aid test systems.
Although the Standard and Chirp Composite signals sound the same to most
people, an analysis tool such as Tempus3D will show the difference between
them. Both the Standard and the Chirp Composite signals are further speech-
weighted to agree with the user-selected composite filter (described in Section
2.3.2.3.)
2.3.2.5 Composite source levels
The Composite signal (and its Digital Speech counterpart) is a complex signal
consisting of 79 different frequency components. When you set the source level
of a composite signal (50 dB, 60 dB, etc), you are actually setting its overall
energy, known as the RMS (root-mean-square) of the signal; you are NOT set-
ting the amplitude of the individual frequency components.
The actual amplitude of each of frequency of the Composite signal is less than
the overall RMS of the signal. See Figure 2.3.2.5 for an example of the ampli-
tudes of each frequency of the Composite signal with an RMS of 70 dB. Be
aware of this difference, especially when viewing frequency response results in
overall amplitude of dB SPL.
Figure 2.3.2.5