The vocal rendering of Pranavam

The vocal  rendering of Pranavam

Pranavam as a whole is famed to have the 

Rishi as Brahma, 

 mother  Gayatri as chhandas, 

and the Supreme lord and the presiding deity.

   The three letters  A  U  and Ma have  Agni, Vaayu and Surya as rishis, 
Gayatri, Thristup and Brihatee as chandaas, and  the triumvirate Brahma, Vishnu and Shiva as presiding deities.

एवमार्षादिकं स्मृत्वा तत ॐकारमभ्यसेत्

सार्द्धत्रिमात्रमुच्चार्य दीर्घखण्डानिनादवत्

evamārṣādikaṁ smṛtvā tata omkāramabhyaset

sārddhatrimātramuccārya dīrghakhaṇḍāninādavat

Thus invoking the Rishis Chandas and Devata, one should chant omkaram..
 If omkaram is pronounced independently it should be for three and half maathras ( a measure of time which may be nearly three and half seconds), that too the rendering should be continuous as if it is coming from the bell of gun metal (khanda used in pujas) with proper reverberation.

त्रिमात्रस्तु प्रयोक्तव्यः सर्वारम्भेषु कर्मसु

तिस्त्रस्सार्द्धस्तु कर्थव्यः मात्रसूत्रार्त्थचिन्तकैः

याज्ञवल्क्यः

trimātrastu prayoktavyaḥ sarvārambheṣu karmasu

tistrassārddhastu karthavyaḥ mātrasūtrārtthacintakaiḥ

yājñavalkyaḥtrimātrastu prayoktavyaḥ sarvārambheṣu karmasu

tistrassarddhastu karthavyaḥ mātrrsūtrārtthacintakaiḥ

yājñvalkya

Sage yaajnvalkya has prescribed that when Omkaram is pronounced as the starting point of a religious rite, the length should be of three maathra or three seconds.  When learned people are contmplating on Omkaram  with maathra  suutra and meaning.

देवताध्यानकाले तु प्ळुतं कुर्यात् न संशयः

तैलधारावदच्छिन्नं दीर्घखण्डानिनादवत्

अप्ळुतं प्रणवस्यान्तम् यस्तम् वेद स वेदवित्

आद्यम् तत्राक्षरं ब्रह्म त्रयी यत्र प्रतिष्ठिता

स गुह्योऽन्न्यस्त्रिवृद्वेदो यो वेदैनं स वेदवित्।

devatādhyānakāle tu pḻutaṁ kuryāt na saṁśayaḥ

tailadhārāvadacchinnaṁ dīrghakhaṇḍāninādavat

apḻutaṁ praṇavasyāntam yastam veda sa vedavit

ādyam tatrākṣaraṁ brahma trayī yatra pratiṣṭhitā

sa guhyo'nnyastrivṛdvedo yo vedainaṁ sa veadavit|

When we are chanting Pranavam in contemplation of deities, undoubtedly it should be chanted in the Plutha mode… 
By plutham it is meant that the flow of sound should be unbroken like the even flow of thailam (gingely oil)  when poured down. 
  However there is a qualification.  
A is the letter of the supreme Brahmam and it should be uttered with secrecy.. 
So the sum and substance of the rule is that the beginning  A part should be rendered with lowered tone, raising to a crescendo when the U and M part comes and then it should taper down slowly to silence in the  later part of M…  
There are limitations of explaining this in words.  
We have to watch the learned preceptors to get the full idea of the audio curve of raise and fall while pronouncing the Pranavam. 

He who understands the proper pronunciation and rendering of Pranavam is famed as the master of all Vedas.

There are more points to discuss about pranvam which  I hope to record in due course.

--