This book is devoted to exercises in estimating changes in sound frequency, sound level, band limitations and irregularities, distortion, noies, etc. It is devoted to a study of the human auditory system-psychoacoustics, if you will. The approach is used in this book to present masking effects, the auditory filters (critical bands), delayed sounds and perception of non-linearities in the ear, what makes some sounds consonant and some dissonant, and other important effects.