Hindi/Urdu natively possesses a symmetrical ten-vowel system. Among the close vowels, what in Sanskrit are thought to have been primarily distinctions of vowel length (that is and ) have become in Hindi/Urdu distinctions of quality, or length accompanied by quality (that is, and ). The historical opposition of length in the close vowels has been neutralized in word-final position, for example Sanskrit loans śakti "energy" and vastu "item" are /ʃəkt̪i/ and /ʋəst̪u/, not /ʃəkt̪ɪ/ and /ʋəst̪ʊ/.
The vowel represented graphically as ऐ ai has been variously transcribed as /ɛ/ or /æ/. Among sources for this article, , pictured to the right, uses ɛ, while and use æ. Furthermore, an eleventh vowel /æ/ is found in English loanwords, such as /bæʈ/ "bat". This article will use ɛ over æ, to distinguish it from English's incoming /æ/.
The standard educated Delhi pronunciations have common diphthongal realizations, ranging from [əɪ] to [ɑɪ] and from [əu] to [ɑu], respectively, in eastern Hindi dialects and many non-standard western dialects. In addition, [ɛ] occurs as a conditioned allophone of /ə/ in proximity to /ɦ/, for example in kahnā [kɛɦnɑ] "to say".
There is disagreement over the issue of nasalization (barring English /æ/ which isn't nasalized). presents four viewpoints of different authors: there are no *[ẽ] and *[õ], undoubtedly due to the effect of nasalization on vowel quality; there is phonemic nasalization of all vowels; all vowel nasalization is predictable; there is phonemic nasalization of the "long" vowels" – – finally and before voiceless stops only, but predictable nasalization of long vowels before voiced stops – because of the presence of an unrecognized homorganic nasal consonant, and of short vowels – – generally. supports the latter most view.
Most native consonants may occur geminate (doubled in length; exceptions are ). Geminate consonants are always medial and preceded by one of the interior vowels (that is, /ə/, /ɪ/, or /ʊ/). They all occur monomorphemically except [ʃː] which occurs only in a few Sanskrit loans where a morpheme boundary could be posited in between (i.e. for [nɪʃːil] "without shame").
For the English speaker, a notable feature of the Hindi/Urdu consonants is that there is a four-way distinction of phonation among plosives, rather than the two-way distinction found in English. The phonations are tenuis, as /p/, voiced, as /b/, aspirated, as /pʰ/, and murmured, as /bʱ/. The last is commonly called "voiced aspirate", though notes that, "Evidence from experimental phonetics, however, has demonstrated that the two types of sounds involve two distinct types of voicing and release mechanisms. The series of so-called voice aspirates should now properly be considered to involve the voicing mechanism of murmur, in which the air flow passes through an aperture between the arytenoid cartilages, as opposed to passing between the ligamental vocal bands."
|Tap or Flap||ɾ|| (ɽ)|
Stops in final position are not released; /ʋ/ varies freely as [v], and can also be pronounced [w]; /ɾ/ can surface as a trill [r], and geminate /ɾː/ is always a trill. The palatal and velar nasals occur only in consonant clusters with a following homorganic stops, as allophones of nasal vowels followed by a stop, and in Sanskrit loanwords. There are murmured sonorants, , but these are considered to be consonant clusters with /ɦ/ in the analysis adopted by .
Loanwords from Persian introduced five consonants not previously found in Indic languages, . Being Persian in origin, these are seen as a defining feature of Urdu. Among these, , also found in English loanwords, are now considered well-established in Hindi; indeed, /f/ appears to be encroaching upon and replacing /pʰ/ even in native (non-Persian, non-English) Hindi words.
The other three Persian loans, (marked green in the chart), are still considered to fall under the domain of Urdu, and are normally assimilated by Hindi speakers to . The sibilant /ʃ/ is found in loanwords from all sources (English, Persian, Sanskrit) and is well-established. Hindi speakers (often non-urban) who fail to maintain (assimilated to ) are thus nonstandard by definition. Yet these same speakers, having a Sanskritic education, may hyperformally uphold /ɳ/ and [ʂ]. In contrast, for native speakers of Urdu, the maintenance of is not commensurate with education and sophistication, but is characteristic of all social levels. are realized as such initially, geminated, and postnasally; as flapped allophones intervocally, finally, and before or after other consonants. However, the adoption of English loans with alveolar stops, which are identified with Hindi/Urdu retroflex rather than dental stops (cf. "bat" above), has led to the emergence of minimal environments (e.g. intervocalic and final [ɖ]), thus conferring marginal phonemic status to the flaps.
Being the main sources from which Hindi/Urdu draws its higher, learned terms– English, Sanskrit, Arabic, and to a lesser extent Persian provide loanwords with a rich array of consonant clusters. The introduction of these clusters into the language in fact contravenes an historical tendency within its native core vocabulary to eliminate clusters through processes such as cluster reduction and epenthesis. lists distinctively Sanskrit/Hindi biconsonantal clusters of initial /kɾ, kʃ, st̪, sʋ, ʃɾ, sn, nj/ and final /t̪ʋ, ʃʋ, nj, lj, ɾʋ, dʒj, ɾj/, and distinctively Perso-Arabic/Urdu biconsonantal clusters of final /ft̪, ɾf, mt̪, mɾ, ms, kl, t̪l, bl, sl, t̪m, lm, ɦm, ɦɾ/.