Bishnupriya Manipuri → IPA Transcription Rules

Rules used in the BM (Bangla script) → IPA converter (with BPM-specific conjunct fine-tuning). This is designed for consistent, dictionary-friendly IPA output, not perfect phonetic detail in every context.

1) Normalization

Input is treated as Bangla-script Bishnupriya Manipuri text.
Hyphen and spaces are preserved. Conversion runs per segment (each part separated by - or spaces).
Apostrophe ' is preserved in output (no special mapping to r).

2) Core letter-to-IPA mapping

2.1 Consonants

Bangla / BPM	IPA	Notes
ব	b
ভ	bʱ
দ / ড	d
ধ / ঢ	dʱ
গ	ɡ
ঘ	ɡʱ
হ / ঃ	ɦ	Both map to `ɦ`
ক	k
খ / ক্ষ	kʰ	Note: conjunct fine-tunes override this for `ক্ষ` forms
ল	l
ম	m
ন / ণ	n
ঞ	g	Default correction: standalone `ঞ` → `g`
ঞ্	n	Halant rule: `ঞ্` → `n`
ঙ / ং	ŋ
প	p
ফ	pʰ
র	r	Correction: `র` → `r`
ৰ / ড়	ɹ	Rule: `ৰ/ড়` → `ɹ`
ঢ়	ɹʱ
চ	cʱ
ছ	sʰ
শ / ষ	ʃ
স	s
ত / ট / ৎ	t
থ / ঠ	tʰ
ৱ	w
জ / য	z	Default: জ/য → z
ঝ	zʱ
য় / য় /য়	y	Correction: `য়` and `য়` → `y`
য় / ্য	j	Original rule: `য়/্য` → `j` (see YA cluster rules below)

2.2 Independent vowels

Bangla / BPM	IPA	Notes
অ	ɔ
আ	a
ই / ঈ	i
উ / ঊ	u
এ	e
ঐ	oi
ও	o
ঔ	ou
ঋ	ri	Correction: ঋ → ri

2.3 Vowel signs (kar)

Sign	IPA
া	a
ি / ী	i
ু / ূ	u
ে	e
ৈ	oi
ো	o
ৌ	ou
ৃ	ri

Special vowel sequence: অ্যা → æ (when parsed as a combined pattern).

3) Halant (্) and inherent vowel (ɔ)

If a consonant has ্ immediately after it, the inherent vowel is suppressed.
If a consonant is followed by a vowel sign, output consonant + that vowel sign’s IPA.
Otherwise, default is consonant + ɔ (inherent vowel).

3.1 Medial schwa deletion (practical rule)

If a consonant is followed by another consonant which has a vowel sign, the earlier consonant may drop its inherent ɔ.
This helps produce BPM-style outputs such as clusters before a clear vowel sign.

3.2 Final inherent vowel tuning (“final ɔ”)

Final ɔ can be dropped or kept depending on the segment-ending pattern.
Rule is applied per segment (each part separated by - or spaces).

This rule is the main knob used during your “ending ɔ” fine-tuning examples (e.g., keeping ɔ in words like অন্ত→ɔntɔ, অন্ধ→ɔndʱɔ, etc.).

4) BPM-specific conjunct fine-tunes (important)

4.1 Special conjuncts (preferred spellings)

ক্ষ → kʰkʰ জ্ঞ (জ্+ঞ) → gya ত্র (ত্+র) → trɔ দ্ব (দ্+ব) → dɔb শ্ন (শ্+ন) → ʃnɔ

4.2 Special: ক্ষ্ম (ক্+ষ্+ম) with vowel sign

Rule: treat ক্ষ্ম as kʰkʰ and drop the “m”.
Then apply the vowel sign after it.

Examples:
লক্ষ্মি   → lɔkʰkʰi
অলক্ষ্মি → ɔlɔkʰkʰi

This rule is applied before the general ক্ষ handling so that ক্ষ্মি does not become kʰkʰmi.

5) Special letter behavior

5.1 জ with halant

Default: জ → z
Special: জ্ → g

5.2 YA cluster behavior

Default: য → z
When YA appears as halant form: ্য behaves like ya (used in outputs like ...jya...).

Examples (desired outcomes):
অনিবার্য্য → ɔnibarjyɔ
অন্তর্যামী → ɔntɔryaami
অন্যায়     → ɔnyay
আর্য্য      → arjyɔ

6) Nasal handling (ŋ)

ঙ and ং map to ŋ.
In certain contexts (e.g., before a consonant that clearly carries a vowel sign), the converter avoids forcing an extra inherent vowel after ŋ.

Examples (as tuned):
অঙ্গ   → ɔŋɡɔ
অংশ   → ɔŋɔʃɔ
সংবাদপত্র → sɔŋbadpɔtrɔ

7) Compound words and punctuation

Hyphen compounds are processed per part and re-joined with -.
The “final ɔ” rule is applied to each part separately.

Examples:
অকরং-বকরং     → ɔkɔrɔŋ-bɔkɔrɔŋ
অইথি-তামথি     → ɔitʰi-tamtʰi

8) Summary checklist

Base Bangla-to-IPA mapping + inherent ɔ.
Halant suppresses inherent vowel.
Vowel signs override inherent vowel.
Medial schwa deletion heuristic in clusters before a vowel sign.
Final ɔ tuning per segment.
BPM conjunct overrides: ক্ষ, ক্ষ্ম, জ্ঞ, ত্র, দ্ব, শ্ন.

Tip: If you maintain a dictionary database, you can always override edge cases by storing the “gold” IPA per entry. The rule set above is intended to be consistent and predictable.