Hindustani phonology
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. Vowel  

 is often realized more open than mid , i.e. as near-open . Vowel  

The open central vowel is transcribed in IPA by either  or . In Urdu, there is further short  (spelled , as in  kamra ) in word-final position, which contrasts with  (spelled , 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. ( –  'energy') and  ( –  'item') are  and , not * and *. Vowels ,  

The vowel represented graphically as  –  (romanized as ) 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,  –  (romanized as ) will be represented as  to distinguish it from , the latter. Despite this, the Hindustani vowel system is quite similar to that of English, in contrast to the consonants. In addition,  occurs as a conditioned allophone of  (schwa) in proximity to , if and only if the  is surrounded on both sides by two underlying, orthographic schwas. 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   ( –  'a story') or   ( –  'outside'). Vowels ,  

The vowel  occurs in proximity to  if the  is surrounded by one of the sides by a schwa and on other side by a round vowel (i.e. in the sequences  or ). It differs from the vowel  in that it is a short vowel. For example, in   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 kept  as diphthongs, pronouncing them as [aɪ~əɪ, aʊ~əʊ]. 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:

 there are no  and , possibly because of the effect of nasalization on vowel quality;
 there is phonemic nasalization of all vowels;
 all vowel nasalization is predictable (i.e. allophonic);
 Nasalized long vowel phonemes () occur word-finally and before voiceless stops; instances of nasalized short vowels () and of nasalized long vowels before voiced stops (the latter, presumably because of a deleted nasal consonant) are allophonic. Masica supports this last view. 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   ('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:

 tenuis, as , which is like  in English spin
 voiced, as , which is like  in English bin
 aspirated, as , which is like  in English pin, and
 murmured, as . 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. 