Rarhi Bengali dialect

Rāṛhī Bengali (রাঢ়ী বাংলা) or Central Bengali, is a dialect of the Bengali language spoken in the southeastern part of West Bengal, in and around the Bhagirathi River basin of Nadia district and other districts of the Presidency division in West Bengal, as well as the Kushtia District region of western Bangladesh. Associated with the Rarh region of eastern India, it forms the basis of the standard variety of Bengali.

Geographical boundaries
This dialect is prevalent in the Rarh region of India specifically in the West Bengal districts of Kolkata, North 24 Parganas, South 24 Parganas, Nadia, Howrah, Hooghly and Purba Bardhaman. It is also spoken natively in the Chuadanga, Kushtia and Meherpur districts of Bangladesh, which were a part of the Nadia district prior to the 1947 Partition of India. Along with Eastern Bengali dialect, Modern Standard Bengali has been formed on the basis of this dialect.

Features
Extensive use of Obhishruti (অভিশ্রুতি, /obʱisrut̪i/, umlaut). E.g. Beng. Koriya (করিয়া, /koria/, meaning - having done) > Beng. Koira (কইর‍্যা, /koirya/) > Beng. Kore (করে, /kore/).


 * The change of অ to ও, when অ is the first sound of a word where the অ is followed by ই(ি), ও(ো), ক্ষ or য. E.g. Ati (written অতি, means 'excess') is pronounced as Oti (ওতি, /ot̪i/).
 * Use of vowel harmony. E.g. Bilati (বিলাতি, /bilat̪i/, meaning - foreign) became Biliti (বিলিতি, /biliti/).

Obhishruti and Opinihiti
Ôbhishruti (অভিশ্রুতি, /obʱisrut̪i/) and Ôpinihiti (অপিনিহিতি, /opinihit̪i/, epenthesis) are two phonological phenomena that occur in spoken Bengali dialects. Opinihiti refers to the phonological process in which a ই or উ is pronounced before it occurs in the word. Obhishruti is the sound change in which this shifted ই or উ becomes removed and changes the preceding vowel. Observe the example above : Koriya (করিয়া, /koria/) > Koirya (কইর‍্যা, /koira/) > Kore (করে, /kore/). First Opinihiti changes Koriya to Koirya (notice how the I changes position.), then Obhishruti changes Koirya (কইর‍্যা) to Kore (করে).