Proto-Iranian language

Descriptive phonology

In addition to the vowels, *H, and *r̥ could function as the syllabic core. In many reconstructions, instances of *iH and *uH occur instead of *ī and *ū.

Phonological correspondences

Development into Old Iranian

The term Old Iranian refers to the stage in Iranian history represented by the earliest written languages: Avestan and Old Persian. These two languages are usually considered to belong to different main branches of Iranian, and many of their similarities are found also in the other Iranian languages. Regardless, there are many arguments that many of these Old Iranian features may not have occurred yet in Proto-Iranian, and they may have instead spread across an Old Iranian dialect continuum already separated in dialects (see Wave theory). Additionally, most Iranian languages cannot be derived from either attested Old Iranian language: numerous unwritten Old Iranian dialects must have existed, whose descendants surface in the written record only later.

Vocalization of laryngeals

The Proto-Indo-European laryngeal consonants are likely to have been retained quite late in the Indo-Iranian languages in at least some positions. However, the syllabic laryngeal (*H̥) was deleted in non-initial syllables.

*l > *r

This change is found widely across the Iranian languages, indeed Indo-Iranian as a whole: it appears also in Vedic Sanskrit. Avestan has no **/l/ phoneme at all. Regardless many words, for which the other Indo-European languages indicate original *l, still show /l/ in several Iranian languages, including New Persian, Kurdish and Zazaki. These include e.g. Persian lab 'lip', līz- 'to lick', gulū 'throat' (compare e.g. Latin gula); Zazaki lü 'fox' (compare e.g. Latin vulpēs). This preservation is however not systematic, and likely has been mostly diminished through interdialectal loaning of r-forms, and in some cases extended by the loaning of words from smaller western Iranian languages into Persian.

*s > *h

Specifically, this debuccalization occurred when not preceded *k, *n, *p, *t or followed *t (which otherwise retained as *s). This change occurs in all Iranian languages.

Aspirated stops

The Proto-Indo-Iranian aspirated stops *pʰ, *tʰ and *kʰ were spirantized into *f, *θ and *x in most Iranian languages. However, they appear to be reverted into aspirates in Parachi, varieties of Kurdish, and the Saka languages (Khotanese and Tumshuqese, but not Wakhi which retains the fricatives); and to have merged with the voiceless aspirated stops in Balochi. In the case of Saka, secondary influence from Gāndhārī Prakrit is likely.

*c, *dz > *s, *z

The Proto-Indo-European palatovelars *ḱ, *ǵ (and *ǵʰ) were fronted to affricates *ć, *dź in Proto-Indo-Iranian (the affricate stage being preserved in the Nuristani languages). The development in the Old Iranian period shows divergences: Avestan, as also most newer Iranian languages, show /s/ and /z/, while Old Persian shows /θ/ and /d/. (Word-initially, the former develops also into /s/ by Middle Persian.) — The change *c > *s must be also newer than the development *s > *h, since this new *s was not affected by the previous change. The consonant cluster *ts (as in Proto-Indo-Iranian *matsya- "fish") has merged to *c, since both were identical in Iranian.

*cw > *sp

This change also clearly fails to apply to all Iranian languages. Old Persian with its descendants shows /s/, possibly likewise Kurdish and Balochi. The Saka languages show /š/. All other Iranian languages have /sp/, or a further descendant (e.g. /fs/ in Ossetian).

*θr > *c

This change is typical for Old Persian and its descendants, as opposed to Avestan and most languages first attested in the Middle or New Iranian periods. Kurdish and Balochi may again have shared this change as well.