Thus here the shruti equates svar, vowels or musical tones to su + varna, pure sound and hence derives suvarna, the word for ‘shining gold’ !
â, î, û (A¸ [ ¸ ]) – the pure vowels
◊ Now, â, î, û (A¸ [ ¸ ]) are the pure vowels. They are pronounced as follows :-
These three are spoken by just pushing the prāna or life-breath and the tongue is not moved but only positioned. The moment the tongue moves, as in speaking most of the other letters, the breath is reflected by it.
The importance of â, î, û (A¸ [ ¸ ]) can be understood from the shlöka :-
aum pūrnamadah, pūrnamidam, pūrnāt pūrnamudacyate
pūrnasya pūrnamādāya pūrnamevāvaśisyate. (Īś.Up.-1) & (Br.Up.- V.1.1)
This is the Shānti pāth at the beginning of Īśāvāsyam Upaniśad and it is also the first shlöka of the fifth adhyāy of the Brihadārānyaka Upaniśad. (This fifth chapter is the beginning of the third kānd or section, and is named khilakānd , the addendum). In both the Upaniśads this shlöka is importantly positioned. It means :-
Om That (Brahman) is Infinite, this (universe) too is infinite. The infinite (universe) emanates, originates from the Infinite (Brahman).
Assimilating the infinitude of the infinite (universe), the Infinite (Brahman) alone is left.
What is pūrna ? It is the root pūr, meaning full or complete and the suffix kta further stresses this meaning, making it more vehement or ‘that which is more than full’ i.e. Infinite. adah ( Ad: ) is ‘that’, a pronoun referring to something that is prökśa or ‘not known to the senses’. idam ( [dma\ ) is ‘this’, a pronoun referring to something that is pratyakśa or here and now. udañch ( ]dHca\ )  is to arise from, to emanate. There are three layers of meaning here as follows :-
adah ( Ad: ) ; idam( [dma\ ) ; udañch ( ]dHca\ )
The syllables are two, three and four ; the â, î, û (A¸ [ ¸ ]) are each combining with the syllable d ( d ) to structure these layers and this is further explained in the next section comprising of three shlökas viz. Br.Up. – V.2.1 to 3. The latter explain the three d ( d ) as dam ( dma ), dān ( dana ), and dyā ( dyaa ) which are the qualities of the Gods, the Devas ; the people, manusya ; and the demons, the asuras respectively. This is asserted by the Goddess of speech, vāg devī as d – d – d (d – d – d ) the sound of the thunder in the clouds.
◊ â ( A ) therefore represents ‘that’ which is the Absolute infinity or Omega, Ω of Cantor’s theory of Infinities . It is Brahman, the Unknown. It is the akśara ( Axar ), the indestructible or the â + swar ( A+svar ).
The following shlökas further underline the above assertions :-
Aitareya Ārāṇyaka II.3.6 
….â+kāraḥ vai sarvā vāk+sa+eṣā sparśaḥ ūṣma abhivyaḥ+ajyamānā . bavhī nānā rūpā bhavati. tasyai yadupāṅśu sa prāṇo atha, yad ucchaiḥ tat śarīraṁ, tasmāt tat tir iva tir iva hai+śarīraṁ+śarīro hi prāṇo atha, yad uccaiḥ tat śarīraṁ, tasmāt tad āvira āvirhi śariraṁ.
……. ‘a’ is the whole of speech and being manifested through the mutes and the sibilants it becomes manifold and various. If uttered in a whisper it is this prāṇa, if forcefully, that body – śarīra. Therefore it is hidden, as hidden as the previous body encapsulated in this prāṇa . But spoken forcefully it is that body and visible, for body is visible.
‘a’ ( A ) is a suffix in every sparśa or ‘mute consonant’ – i.e from kâ ( k ) to mâ ( ma ) and in the sibilants śâ, sâ, sâ, hâ ( Sa¸ Ya¸ sa¸ h ). This is a very interesting structure in Sanskrit. Now not only ‘a’ ( A ) is a suffix in every consonant of the alphabet and from there it pervades into every spoken word or sentence, thus it is also the symbol for Brahman, the Unknown……and this is precisely what is restated by Lord Kriśna in Gītā 10.33…
akśarānām â+kārah asmi dwandwah sāmāsikasya ca. aham eva
akśayah kālah dhātā aham viśwatomukhah . 10.33
I am the letter ‘a’ among the vowels of the alphabet and the dwanda compound in relation to the words collectively. I am indestructible time. I am the Dispenser facing everywhere.
Thus â ( A ) stands for Brahman, the Unknown…
◊ î ( [ ) is ‘this’ continuity at hand . It is the î+swar ( [|+svar ) or the īśwara, the God that is manifest and pratyakśa or lies within the realm of our senses. It is the Aleph 1, א1 – the continuous infinity of Cantor’s theory of Infinities. It is uncountable, as rigorously proved in the reference, and from this emerges the countable infinity again and again without diminishing it.
idam( [dma\ ) is linked to Lord Indra , after whom our senses are named indriyān. (Indra appears in Rig Veda and is synonymous with the later concept of Īshwara , this is explained by S.Radhakrishnan )…..
sa etameva purusambrahm tatmam+apaśyat. idamadarśam itīm.
tasmāt idamdro ha vai nām. tamidamindra santam+indra ityācakśate
prokśain . prokś+priyā iva hi devāh , prokś+priyā iva hi devāh .
Aitareya Ārānyaka II.4.3 & Aitareya Upaniśad I.3.14 
He saw this purusa (the first born), as the constituent of the Brahman, over-spreading all. With wonder he said, idamadarśam – “Oh ! I have seen this.” Therefore He is called idamdra (idam+dra). Idamdram, verily is His name. Though He is indirectly called Indra. The Devas or Gods are fond of the cryptic ; the Gods are indeed fond of being called indirectly.