Jai sri Ganesha,
Indeed there is process of inhalation and exhalation which makes being survive on the sphere of life,
And that too pitched at sound current to remind man unto truth of its identity as revealed by the ancient sages in the book of time,
In Inhalation-it sounds like So-means alike that supreme personality,
In Exhalation-it sound like Hum-means am alike that,
May Lord bless all,
Thanks please