Hindustani is the lingua franca of northern India and Pakistan, and through its two standardized registers, Hindi and Urdu, a co-official language of India and co-official and national language of Pakistan respectively. Phonological differences between the two standards are minimal.

Vowels

Hindustani natively possesses a symmetrical ten-vowel system. The vowels are always short in length, while the vowels, , , , , , are usually considered long, in addition to an eleventh vowel which is found in English loanwords. The distinction between short and long vowels is often described as tenseness, with short vowels being lax, and long vowels being tense. Vowels are somewhat longer before voiced stops than before voiceless stops. Additionally, and occur as conditional allophones of.

Vowel

is often realized more open than mid, i.e. as near-open. It is subject to schwa deletion word-medially in certain contexts.

Vowel

The open central vowel is transcribed in IPA by either or. In Urdu, there is further short (spelled ہ, as in کمرہ kamra ) in word-final position, which contrasts with (spelled ا, as in laṛkā ). This contrast is often not realized by Urdu speakers, and always neutralized in Hindi (where both sounds uniformly correspond to ).

Vowels, ,

Among the close vowels, what in Sanskrit are thought to have been primarily distinctions of vowel length (that is and ), have become in Hindustani distinctions of quality, or length accompanied by quality (that is, and ). The opposition of length in the close vowels has been neutralized in word-final position, only allowing long close vowels in final position. As a result, Sanskrit loans which originally have a short close vowel are realized with a long close vowel, e.g. śakti (शक्ति – 'energy') and vastu (वस्तु – 'item') are and, not * and *.

Vowels ,

The vowel represented graphically as ऐ – (romanized as ai) has been variously transcribed as or. Among sources for this article,, pictured to the right, uses , while and use. Furthermore, an eleventh vowel is found in English loanwords, such as ('bat'). Hereafter, ऐ – (romanized as ai) will be represented as to distinguish it from, the latter. In addition, occurs as a conditioned allophone of (schwa) within the sequence ( before the next syllable or word-finally due to schwa deletion). This change is part of the prestige dialect of Delhi, but may not occur for every speaker. Here are some examples of this process: However, the fronting of schwa does not occur in words with a schwa only on one side of the such as kahānī (कहानी – 'a story') or bāhar (बाहर – 'outside').

Vowels ,

The vowel occurs in proximity to if the is surrounded on one of the sides by a schwa and on other side by a round vowel (due to Hindustani phonotactics, this generally only occurs in the sequences or ). It differs from the vowel in that it is a short vowel. For example, in bahut the is surrounded on one side by a schwa and a round vowel on the other side. One or both of the schwas will become giving the pronunciation. Some Eastern dialects keep as diphthongs, pronouncing them as.

Nasalization of vowels

As in French and Portuguese, there are nasalized vowels in Hindustani. There is disagreement over the issue of the nature of nasalization (barring English-loaned which is never nasalized ). presents four differing viewpoints: Masica supports this last view.

Vowel orthography with diacritics and English approximations

The principal vowel phonemes may be organised as follows to demonstrate the orthographic conventions for vowels.

Consonants

Hindustani has a core set of 28 consonants inherited from earlier Indo-Aryan. Supplementing these are two consonants that are internal developments in specific word-medial contexts, and seven consonants originally found in loan words, whose expression is dependent on factors such as status (class, education, etc.) and cultural register (Modern Standard Hindi vs Urdu). 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,, , or ). They all occur monomorphemically except, which occurs only in a few Sanskrit loans where a morpheme boundary could be posited in between, e.g. for niśśīl ('without shame'). For the English speaker, a notable feature of the Hindustani 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: 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.'" The murmured consonants are believed to be a reflex of murmured consonants in Proto-Indo-European, a phonation that is absent in all branches of the Indo-European family except Indo-Aryan and Armenian. Stops in final position are not released, although they continue to maintain the four-way phonation distinction in final position. varies freely with, and can also be pronounced. is usually flapped or trilled. In intervocalic position, it may have a single contact and be described as a flap, but it may also be a clear trill, especially in word-initial and syllable-final positions, and geminate is always a trill in Arabic and Persian loanwords, e.g. zarā (ज़रा – 'little') versus well-trilled zarrā (ज़र्रा – 'particle'). The palatal and velar nasals occur only in consonant clusters, where each nasal is followed by a homorganic stop, as an allophone of a nasal vowel followed by a stop, and in Sanskrit loanwords. However /n/ + velar clusters also occur, eg. /ʊn.kaː/ making /ŋ/ phonemic. There are murmured sonorants,, but these are considered to be consonant clusters with in the analysis adopted by. The fricative in Hindustani is typically voiced (as ), especially when surrounded by vowels, but there is no phonemic difference between this voiced fricative and its voiceless counterpart. Hindustani also has a phonemic difference between the dental plosives and the so-called retroflex plosives. The dental plosives in Hindustani are laminal denti-alveolar as in Spanish, and the tongue-tip must be well in contact with the back of the upper front teeth. The retroflex series is not purely retroflex; it actually has an apico-postalveolar (also described as apico-pre-palatal) articulation, and sometimes in words such as ṭūṭā (टूटा – 'broken') it even becomes alveolar. In some Indo-Aryan languages, the plosives and the flaps are allophones in complementary distribution, with the former occurring in initial, geminate and postnasal positions and the latter occurring in intervocalic and final positions. However, in Standard Hindi they contrast in similar positions, as in nīṛaj (नीड़ज – 'bird') vs niḍar (निडर – 'fearless').

Allophony of and

Hindustani does not distinguish between and, specifically Hindi. These are distinct phonemes in English, but conditional allophones of the phoneme in Hindustani (written ⟨व⟩ in Hindi or ⟨⟩ in Urdu), meaning that contextual rules determine when it is pronounced as and when it is pronounced as. is pronounced in onglide position, i.e. between an onset consonant and a following vowel, as in pakwān (पकवान, 'food dish'), and elsewhere, as in vrat (व्रत , 'vow'). Native Hindi speakers are usually unaware of the allophonic distinctions, though these are apparent to native English speakers. In most situations, the allophony is non-conditional, i.e. the speaker can choose, , or an intermediate sound based on personal habit and preference, and still be perfectly intelligible, as long as the meaning is constant. This includes words such as advait (अद्वैत ) (pronounced [əd̪ˈʋɛːt̪]), which can be pronounced equally correctly as or.

External borrowing

Sanskrit borrowing has reintroduced and into formal Modern Standard Hindi. They occur primarily in Sanskrit loanwords and proper nouns. In casual speech, they are sometimes replaced with and. does not occur word-initially and has a nasalized flap as a common allophone. Loanwords from Persian (including some words which Persian itself borrowed from Arabic or Turkish) introduced six consonants,. Being Persian in origin, these are seen as a defining feature of Urdu, although these sounds officially exist in Hindi and modified Devanagari characters are available to represent them. Among these,, also found in English and Portuguese loanwords, are now considered well-established in Hindi; indeed, appears to be encroaching upon and replacing even in native (non-Persian, non-English, non-Portuguese) Hindi words as well as many other Indian languages such as Bengali, Gujarati and Marathi, as happened in Greek with phi. This to shift also occasionally occurs in Urdu. While [z] is a foreign sound, it is also natively found as an allophone of /s/ beside voiced consonants. The other three Persian loans,, are still considered to fall under the domain of Urdu, and are also used by some Hindi speakers; however, other Hindi speakers may assimilate these sounds to respectively. The sibilant is found in loanwords from all sources (Arabic, English, Portuguese, Persian, Sanskrit) and is well-established. Some Hindi speakers (especially those from rural areas) pronounce the sounds as , though these same speakers, having a Sanskritic education, may hyperformally uphold and. In contrast, for native speakers of Urdu, the maintenance of is not commensurate with education and sophistication, but is characteristic of all social levels. The sibilant, found in loanwords from Persian, Portuguese, and English, is very rare and is considered to fall under the domain of Urdu; although it is officially present in Hindi, many speakers of Hindi assimilate it to or. Being the main sources from which Hindustani 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 contravenes a 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 and final, and distinctively Perso-Arabic/Urdu biconsonantal clusters of final.

Suprasegmental features

Hindustani has a stress accent, but it is not as important as in English. To predict stress placement, the concept of syllable weight is needed: Stress is on the heaviest syllable of the word, and in the event of a tie, on the last such syllable. If all syllables are light, the penultimate is stressed. However, the final mora of the word is ignored when making this assignment (Hussein 1997) [or, equivalently, the final syllable is stressed either if it is extra-heavy, and there is no other extra-heavy syllable in the word or if it is heavy, and there is no other heavy or extra-heavy syllable in the word]. For example, with the ignored mora in parentheses: Content words in Hindustani normally begin on a low pitch, followed by a rise in pitch. Strictly speaking, Hindustani, like most other Indian languages, is rather a syllable-timed language. The schwa has a strong tendency to vanish into nothing (syncopated) if its syllable is unaccented.