#Sound Change Applier (SCA)

Define and preview diachronic sound change rules to simulate historical language evolution.

Navigate: click Sound Changes in the sidebar.

#Character Mode

Define rules by specifying target and replacement characters:

Macros expand automatically: V → vowel list, C → consonant list.

#Boundary markers

• #: word boundary (compatible form)
• ^: word-initial boundary alias
• $: word-final boundary alias

Use them to express strictly word-initial/word-final changes.

#Example

"Voicing of voiceless stops between vowels":

• Target: p t k
• Replacement: b d g
• Pre-context: V
• Post-context: V

#Feature Mode

Define more precise rules based on phonetic features:

• Target features: Use +/- to specify (e.g., [+voiced, -stop])
• Replacement features: Specify features to set/remove
• Phoneme matching: Real-time display of all phonemes matching the specified features
• Jaccard similarity: Auto-finds the closest IPA phoneme after feature replacement
• Feature inverted index: O(1) query acceleration

Feature mode also supports boundary-aware constraints for edge-specific rules.

#Preview

• Single word test: Input a word → see sound change result + step-by-step log
• Batch preview: Changed-only table with pagination over all changed items
• Apply to lexicon: Write back changed lexicon forms
• Apply to grammar rules: Optional (per-rule toggle) for inflection/derivation fields

#Batch table columns

• Scope: Lexicon / Inflection / Derivation
• Target: entry or rule name
• Field: changed field (affix/infix/circumfix/ablaut etc.)
• Original / Result: before-after values

#Step-by-step workflows

#Workflow 1: Create and verify one ruleset

1. Add a new ruleset (for example Early Shift).
2. Add one character-mode rule: p t k -> b d g with context V _ V.
3. Run Single Word preview on 5 sample words.
4. Confirm changelog order and expected outputs.
5. Save and proceed to batch preview.

#Workflow 2: Safe batch apply to lexicon

1. Switch to Batch Preview.
2. Verify changed count and page through all changed rows.
3. Confirm no unintended high-frequency roots are affected.
4. Click Apply to update lexicon entries.

#Workflow 3: Apply to selected grammar rules (advanced)

1. In Grammar, enable Allow SCA edits only for target rules.
2. Return to SCA -> Batch Preview.
3. Filter mentally by Scope and Field.
4. Apply and then run Grammar -> Inflection Test.
5. If needed, disable toggles again.

#Advanced examples

#Example A: Word-final devoicing

Rule:

• target: b d g
• replacement: p t k
• after context: $

Validation:

1. tab -> tap
2. dag -> dak
3. Ensure medial b d g remain unchanged.

#Example B: Feature-based spirantization

Rule idea:

• target features: stop consonants in intervocalic position
• replacement features: remove stop, add fricative-like features

Validation:

1. Test on known VTV environments.
2. Inspect feature detail log for each replacement.
3. Confirm resulting IPA symbols are expected.