Sound and Letter
A dhoni is the smallest unit of sound in a spoken word, and a borno is the written symbol for a sound.
The Bengali Alphabet
The Bengali alphabet has fifty letters in total. There are eleven vowels: o, aa, i, ii, u, uu, ri, e, oi, o and ou. There are thirty-nine consonant letters: thirty-two from ko to ho, three more (rro, rrho and yo with a dot), and four extra signs (khanda-to, anusvar, visarga and chandrabindu). There are seven basic vowel sounds: o, aa, i, u, e, a-with-e (as in ae) and o. The letters oi and ou are diphthongs.
Classification of Consonants
By place of articulation: guttural (throat) are ko, kho, go, gho and ngo; palatal are cho, chho, jo, jho and nyo; retroflex are the hard t-group letters; dental are the soft t-group letters (to, tho, do, dho and no); labial are po, pho, bo, bho and mo. The twenty-five letters from ko to mo are called sporsho barno (stops). Antahstha letters are yo, ro and lo. Ushma or sibilant letters are the palatal sho, the retroflex sho, the dental so and ho. Nasal letters are ngo, nyo, the retroflex no, the dental no and mo.
Unvoiced letters include ko, kho, cho, chho, to, tho, po, pho and the sibilants. The rest are voiced. In each group, the first and third letters are unaspirated and the second and fourth are aspirated.
Sound Changes
Adding a vowel at the start is called shorager, as in school becoming ishkul. Apinihiti moves an i sound forward, as in koriya becoming koiro. Obhishruti then smooths that into kore. Vowel harmony, called shorosongoti, changes deshi to dishi. Assimilation, called shomibhobon, changes golpo to gopno. Dissimilation, called bishomibhobon, changes lal to nal. Sound loss changes Kolikata to Kolkata. Metathesis reverses letters, as in bakso becoming basko (rearranged letters).
Shortcut
The consonant groups follow the order throat, palate, roof of mouth, teeth and lips. In every group the second and fourth letters are aspirated.
Worked Examples
Example 1: What kind of letter is 'dho'?
Solution: It is the fourth letter of the dental group, so it is dental, voiced and aspirated.
Example 2: What sound change is 'bilati' to 'biliti'?
Solution: Vowel harmony: the later i pulls the earlier aa into i.
Quick Check
Question 1: How many letters does the Bengali alphabet have?
Answer: Fifty.
Question 2: How many basic vowel sounds are there?
Answer: Seven.
Question 3: Which group is 'cho, chho, jo, jho, nyo'?
Answer: Palatal.