Now let us ponder over the meanings behind the vyahritis.
The pranavam, which precedes every vyahriti is the combination of akaara ukaara and makaara and in this combination it represents the triumvirate Brahma Vishnu and Maheswara who are the manifestation of the supreme brahmam.
The seven vyahritis can be defined only in conjunction with the Pranavam and it has to be considered that pranavam is the integral part of each vyaahriti.
If we consider each vyahriti along with the pranavam.
Om bhuuH.. bhuu is the embodiment of Satta or the essence of existence and it is one with brahmam in combination with pranava.
Om BhuvaH… bhuvaH represents the stithi or the present existence of all things and it is one with brahmam in combnation with pranava.
Om SuvaH.. this is invoked by the harbingers of welfare and prosperity like the rishis Sanaka… vring varane(वृङ्ग् वरणे) representing Va preceded by Su shobane..( सु शोभने) (meaning that it attracts all that is shobanam) -- and in conjunction with pranavam this vyahriti also represents brahmam.
Om MahaH… this is the vyahriti invoked by the great souls seeking emancipation or moksham form mundance existence (MahaH poojaayam महः पूजायाम्) is also the ultimate brahmam in conjunction with pranava.
Om janaH.. this vyahriti represents the creation of the entire universe (janee praadhurbhaave.. जनी प्रादुर्भावे) and in conjunction with pranava, this also represents brahmam.
Om tapaH.. the energy which is inherent in all beings and present in its manifest form in the effulgent sun and is setting all beings into action.. is represented by this vyahriti (तपति इति तपः) and in conjunction with pranva this again represents the supreme brahma.
Om Satyam… Satyam is one that is not affected or destroyed by space, time, matter or any other existing stimuls, and one that has no destruction because it was never born but was ever existent (न जायते म्रियते वा कदाचित् ----गीतायां it is never born so it has no death.. cf Gita), and it represents the absolute truth and in conjunctin with pranava it again becomes the supreme brahma…
So while contemplating on the seven vyahritis during japa and pranayama we have to be conscious that we are invoking into our own beings the supreme brahma in the shape of pranava, the triumvirate and the seven forms as discussed above.