Phonogram Theory considers sound recording not as a technological process, but as the result of this process in the form of a phonogram, focusing on those theoretical problems that are associated with the physical processes of formation of phonograms and the distortions that arise in them. Recording equipment (recording elements, recording media, etc.) are set forth only in terms of their characteristics affecting the quality of phonograms." Phonogram theory," indicating ways to obtain phonograms and improve their quality, is the basis for studying technology and equipment for recording and reproducing sound.