Building Acoustics

20 Building acoustics

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

Timet(s)

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

x(

t)

Figure 1.14 Example of a periodic signal with added Gaussian noise signal (normally distributed noise). The
periodic signal is identical to the one shown in Figure 1.3.

Figure 1.15 The Fourier transform of the signal given in Figure 1.14.

0 100 200 300 400 500

Frequency (Hz)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

|X

(f

)| (RMS)

The next subject one should address is the accuracy of the amplitude values for the
frequency lines. When the power spectrum is the goal (see Equation (1.20)), using the
process outlined in the example above we have got an estimate based on the analysing