ABSTRACT
The most basic of needs in audio measurement is to determine a value relating to the size, or amplitude, of an analog audio signal. To address the signal peak issues and find an efficient level below overload, peak level meters or peak program meters were developed to read the near-instantaneous value of the audio signal. A great deal of work has been done on audio signal measurement by members of the International Telecommunications Union and European Broadcast Union. A real-time audio analyzer consists of a sequential collection of one octave or one-third octave filters having individual detectors and indicators at each output. Simple audio distortion can be characterized in two ways: total harmonic distortion (THD) and intermodulation distortion (IMD). The two effects produce measurements that are often expressed by single, unrelated numbers. Modern audio analyzers perform a Fast Fourier Transform on an audio signal and mathematically transform the result into an amplitude display of the frequency components present.
