In general, the loudness of a sound depends on the size of the variations in air pressure that occur, whereas the intensity is proportional to the average size, or amplitude, of the variations in air pressure. It is usually measured in decibels, usually abbreviated as dB, relative to the amplitude of some other sounds. A rough assessment of the comparative intensity of two sounds can be made by reference to their waveforms. In any utterance, the actual intensity of a segment depends on many factors, such as its position in the sentence, the degree of stress on each word, and so on. We calculated it as the power with window normalization, and the third line of Figure 2.3 shows an example of the loudness for the sentence.
