Manichean Sogdian: Coalescence of Phonemes
Linguists describe phonemes by their features. For example, the features of /s/ are sibilant, alveo-dental, and unvoiced; the features of /z/ are sibilant, alveo-dental, and voiced. The difference between /s/ and /z/ is that z is voiced.
Similar phonemes /š/ and /ž/ are different from the above phonemes in that they are alveo-palatal, not alveo-dental. The difference between /š/ and /ž/ mirrors that between /s/ and /z/, that is, unvoiced vs. voiced.
As I look through the Sogdian lexicon I notice that words can start with any of the following: s, š, z, j (ž). Some words may start with č, such as čarm (skin, hide). Although there is a distinction between č and ž, it seems from the orthography that there is no distinction between j/ǰ and ž. This distinction was apparently preserved in Manichean Parthian, as explained in an article from 2010, "Parthian ž" by Agnes Korn. In the abstract for the article Korn states:
"This article argues that the opposition between Old Iranian *č and *ǰ was preserved in Manichaean Parthian not only word-initially, but also in postvocalic position, at least at the time of the introduction of the Manichaean script. The approach is phonological, and attempts to show that Pth. /č/(< OIr. *č), written
and , and Pth.
/ž/(< Oír. *ǰ and *ž), written z̈> , are consistently
distinguished in the Manichaean script. Pth. /č/ may have developed a
postvocalic allophone [ǰ] (not affecting the phonematic opposition),
which might have been a motivation for the use of the letter < ."
According to Korn, even if the Manichean Parthian developed a postvocalic allophone, it would not have affected the distinction between the two phonemes. However, the distinction was not preserved in the Sogdian. The phonemes coalesced, as Korn further explains in the last statement of the abstract:
"Transcriptions into Sogdian script and the cantillations suggest a coalescence of the Pth. phonemes, but it is not clear whether this is a later development of the Pth. language itself or a peculiarity of the liturgical pronunciation of Parthian as practised by Manichaeans in Central Asia."
Korn, Agnes. Parthian ž. Bulletin of the School of Oriental and African Studies, University of London , Vol. 73, No. 3 (2010), pp. 415-43.