Allophonic and Phonotactic Constraints Are Useful

It is well known that phonemes have different acoustic/phonetic realizations depending on the context. For example, the phoneme / t / is typically realized with a different allophone (phonetic variant) in syllable initial position than in syllable final position. In syllable initial position (e.g., Lorn), / t / is almost always released (with a strong burst of energy) and aspirated (with / h / like noise), whereas in syllable final position (e.g., ca[), / t / is often unreleased and unaspirated. It is common practice in speech research to distinguish acoustic/phonetic properties that vary a great deal with context (e.g., release and aspiration) from those that are relatively invariant to context (e.g., place, manner and voicing). In the past, the emphasis has been on invariants; allophonic variation is traditionally seen as problematic for recognition.