/**
 * Simplified port of espeak-ng's English letter-to-phoneme rules.
 *
 * Parses the en_rules file format and applies rules to convert
 * unknown English words to IPA phonemes.
 */
/**
 * Convert espeak internal phoneme string to IPA.
 */
export declare function espeakToIPA(espeak: string): string;
/**
 * Parse the en_rules file and populate RULE_GROUPS and LETTER_GROUPS.
 */
export declare function parseRules(rulesText: string): void;
/**
 * Convert a word to IPA using the rule engine.
 */
export declare function wordToIPA(word: string): string;
/**
 * Initialize the rule engine with the rules text.
 * Call this once with the contents of en_rules.
 */
export declare function initRules(rulesText: string): void;
export declare function isRulesLoaded(): boolean;