Masking effect
When multiple audio signals simultaneously interact with each other, a masking effect occurs, when one signal is masked and the other is masked.
This interaction has a different effect on the sound that a person hears later. There may be the effect of not hearing one tone on an equal footing with another (the masking tone completely excludes the masked one). This usually occurs when there is a large difference in the intensity of the tone and the sound pressure. For example, a loudly passing train can almost completely mask the sound of a medium-intensity human voice. Shouting Another variant of masking occurs in the form of signal distortion or a change in the timbre of the sound. As in many other aspects of human perception of sound information, the preference for the human system of perception of sound in the case of masking is given to the middle frequencies, which corresponds to the segment of perception of speech and the voice of other people and it is due to the biological formation of the human individual. Masking processes occur in the upper parts of the brain and look like this: if there are two tones of sound or signals of different intensities, both are received simultaneously by the peripheral auditory system and sent for further processing and analysis to the brain. However, at this stage, the person will hear only one of the signals, the most intense. But this does not negate the fact that two different sound tones are emitted, it is just that a person finally hears only one of them. This is roughly how the masking effect works, which is of four types:
simultaneous masking (monaural);
non-simultaneous (temporary) masking;
central masking (binaural);
binaural unmasking;
Simultaneous (monaural) masking – This is the most common case that occurs constantly in practice and in everyday life. This phenomenon is characterized by the simultaneous appearance of sound waves and is manifested the louder, the more intense is the masking sound in relation to the masking, and this occurs in direct proportion. The degree of masking in this case is easily represented in decibels (dB), as the difference between the threshold level of hearing of a given tone in the presence of a masking tone and its threshold level of hearing in silence. But this doesn’t end with the features of simultaneous masking. The degree of masking is greater and depends not only on the increase in intensity of one sound wave in relation to another. The most pronounced masking occurs when the frequency of the masked sound is closest to the frequency of the masked sound. Consequently, the greater the difference in frequency, the less the effect manifests itself. Furthermore, masking becomes increasingly asymmetrical in relation to high-frequency sounds, whenever the intensity of the masking sound increases. The peculiarity of the specificity of sound processing by human hearing organs also causes such an interesting effect: high-frequency maskers work effectively (mask) in a fairly narrow frequency range, while low-frequency tones cover a range of much wider frequency.
