Tehrani accent is the most common colloquial variant of the modern Persian language

Persian language

Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...

. Compared to literary standard Persian, the Tehrani dialect lacks original Persian diphthong

Diphthong

A diphthong , also known as a gliding vowel, refers to two adjacent vowel sounds occurring within the same syllable. Technically, a diphthong is a vowel with two different targets: That is, the tongue moves during the pronunciation of the vowel...

s and tends to fuse certain sounds. Tehrani accent of Persian language should not be confused with the old Tehrani dialect, which was a northwestern Iranian dialect, belonging to the central group

Dialects of Central Iran

Central Iranian, or Central Iran, is a group of Western Iranian languages spoken in villages and towns of central Iran, mostly in Markazi and Isfahan provinces...

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Differences with the standard Persian

Here are some of the main differences between the Tehrani colloquial Persian and standard Persian:

• standard Persian ("ān", "ām") ↔ Tehrani ("un", "um"). Example: "bādām" ↔ "bādum"
• "ow" ↔ "o". Examples: "borow" ↔ "boro", "nowrūz" ↔ "noruz"
• "zd" ↔ "zz". Example: "dozdi" ↔ "dozzi"
• "st" ↔ "ss". Examples: "daste" ↔ "dasse", "peste" ↔ "pesse"
• "e" ↔ "i". Examples: "jegar" ↔ "jigar", "shekār" ↔ "shikār", "keshmesh" ↔ "kishmish"