1. Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
Rohit Kumar *, Amit Kataria, Sanjeev Sofat
Department of Computer Science and Engineering
Punjab Engineering College, Chandigarh
* Language Technologies Research Center
IIIT Hyderabad

2. Outline of the Presentation
Introduction
Need, Problems, Suggestion
Overview of the Approach
Grapheme to Phoneme Alignment
Applying the Rules
Approaches for Building the Rules
Conclusion
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

3. Introduction: Need for Pronunciation Lexicons
TTS - Text Processing Modules for Non Phonetic Languages like English for Pronunciation Lookups
Building Letter to Sound rules by Learning Approaches
Building Language Models for Recognition Systems
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

4. Introduction: Appearance of Pronunciation Variations
Pronunciation Variations arise when foreign language is spoken by non – native speakers
Speakers try to speak the foreign language under the pronunciation constraints of their native language
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

5. Introduction: Problem & Suggestion
Pronunciation Lexicon building is a time consuming manual process
Since, Lexicons are needed, how do we build these up rapidly and semi automatically with minimal effort.
Pronunciation Lexicon in Native pronunciation of Foreign Languages are easily available (particularly for English)
A Rule based approach using these Native Lexicons to build Non Native Lexicons is proposed.
An Example based approach for Rule Building is also suggested
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

6. Overview of the Approach: 3 Step Process
Step 1: Word Lookup:
lieutenant > l e f t e n t
Step 2: Grapheme – Phoneme Alignment l i e u - t n a % f @
Step 3: Rule Application l % e f t n @ tz
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

7. Overview of the Approach: Issues
How to do Grapheme Phoneme Alignment ? (Step 2)
How the Rules are triggered and how do they work ? (Step 3)
How to come up with the Rules ?
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

8. Grapheme – Phoneme Alignment
Problem is that a Phoneme (Grapheme) may match with zero, one or many Graphemes (Phonemes)
Algorithm based on matching the phoneme with a grapheme from its list of possible grapheme
Consonant Phoneme matches with Consonant Grapheme and Vowel Phoneme Matches with possible Vowel Phoneme (a, e, i, o, u, y) $ o b s c - u re l y @ k % ii
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

9. Format of Rules
5 Fields
Left Context LC
Source Phoneme PH
Right Context RC
Corresponding Grapheme GR
Target Phoneme OPH
Wild Cards (*) are allowed
Phonemes are represented by a bit pattern (and hence a number) describing their phonetic properties
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

10. Issue: What should be the shape of the Window shown ??
Applying the Rules
LC = * ; PH ; RC = * ; GR = “o” ; OPH = “au” ; $ o b s c - u re l y @ k % ii au r
LC = * ; PH = % ; RC = * ; GR = “re” | “r” ; OPH = “r” ;
Issue: What should be the shape of the Window shown ??
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

11. Building the Rules Manually (observe and write) Example based Approach
Map each source phoneme to nearest target phoneme
Find English words with a native pronunciation different from that obtained by the above mapping
Automatically forms rules to model the difference that is observed
Merge the newly formed rules with existing rules
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

12. Building the Rules Example Based Approach$ a l m o n d s aa % @ z
LC = aa ; PH = % ; RC = m ; GR = “l”; OPH = “l” ;
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

13. Building the Rules Example Based Approach (contd.)
MERGING OF RULES
New Rule:
LC = aa ; PH = % ; RC = m ; GR = “l”; OPH = “l”;
Existing Rule:
LC = e ; PH = % ; RC = b ; GR = “ll”; OPH = “l”;
Merged Rule:
LC = aa|e; PH = % ; RC = m|b ; GR = “l”|”ll”; OPH = “l”;
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019

14. Conclusion
Reuse of information available in existing lexicon along with Rules can help in rapid creation of non native lexicons
Algorithm for Grapheme to Phoneme is presented
Issue of Window Shape for rule application needs further experimentation
Example based approach can be used for rule building
Building Non Native Pronunciation Lexicon for English using a Rule Based Approach
2/28/2019