Is there some meditation like counting the rhythm of breaths by using the word 'so ham'? Is the hong shau technique actually read or spelled as 'ham sa'? What is the difference in using 'so ham' or 'ham sa'?
Hong-Sau can be pronounced in slightly different ways. Fortunately for us, the mantra is said only silent in synchronization with the breath: Hong (rhymes with “song”) as the incoming breath is felt rising through the nostrils; and, “Sau” (pronounced like the verb, “saw”). But, depending on one’s language or dialect, it might also be pronounced something like “Haam Shaw” or something similar to this.
Paramhansa Yogananda explained that the mantra Hong Sau is used instead of So Hum because the former means “I am HE” while the latter means “He is I”: until one has achieved enlightenment, he explained, it is more correct to affirm I AM HE rather than state categorically that HE IS I.
Evidently there is a Upanishad sloka called the Hong Sau sloka that gives the mantra in that form and not the form of So Hum.
It is nonetheless a fact that various teachers give the mantra as So Hum. One should use this according to the instructions given to you by your teacher. Yogananda gave us the mantra as Hong Sau so this is how we use it.
I will not attempt to teach the technique in a note like this but instruction in the Hong Sau is readily available on the various Ananda websites and the Ananda meditation app (as well as several books by Ananda’s founder, Swami Kriyananda — a direct disciple of YOGANANDA).
I hope this helps and clarifies.
Sincerely and with blessings flowing,
Seattle WA USA