The International Electrotechnical Commission (IEC) has defined a noise input signal representative for normal programme material. It is generated by a pink or white noise source followed by a filter. We will refer to this signal as the "IEC signal", and investigate if it is useful for efficiency measurements (more of this in next articles).
Characteristics
Picture 1 shows that the amplitude distribution of the IEC signal is gaussian.
Picture 1: Amplitude distribution of the IEC-268 test signal and a gaussian curve as reference
Picture 2 shows the IEC signal frequency distribution, together with the distribution of the fragments (discussed in Characteristics of Audio Signals). The IEC signal serves well as a typical audio fragment.
Picture 2: Frequency distribution of the fragments and of the IEC test signal (fat line)
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