Sutras 1.27 - 1.28. The mechanisms of mantras effect (continuation)

In addition to and in confirmation of the foregoing I shall adduce a popular article in which they give the results of the latest speech physiology studies. 

Our particular interest is drawn by the “mechanics of phonetics” section [the original English text is here – transl.note], the investigation in which they have used the state-of-the-art methods of brain study (and I admit to look on this with admiring envy since in our research work we can so far use classical encephalography only) to show that the process of different sounds articulation involves different zones of the brain. 

Sutras 1.27 - 1.28. Sanskrit and mantra-yoga

The following two lines of Yoga Sutras are dedicated to mantras and power of the sound.

तस्य वाचकः प्रणवः ॥२७॥

1.27. tasya vācakaḥ praṇavaḥ

तज्जपस्तदर्थभावनम् ॥२८॥

1.28. tajjapastadarthabhāvanam 

Sutras 27 and 28 tell that “the expression of that (Isvara) is OM (pranava)” and “the repetition of it (Om) in one mind’s eye allows one to experience it (the Isvara)”. Without getting into specifics of what the Om-sound means let us raise a more important question: why do mantras generally exist and how do they work?