When is a stop aspirated

A simple answer to the question is this: A stop is aspirated when a linguist/phonetician judges it to be so. This property, often referred to in descriptions of the stop consonants of English and many other languages, has been variously defined in physical terms, aerodynamically, articulatorily, and acoustically. Linguists seem generally to agree that in English aspiration is a predictable, i.e., context determined, and hence a nondistinctive attribute of/p t k/in certain contexts. In some other languages, e.g., Hindi, aspiration is a distinctive feature of certain stop phonemes, so that [t] contrasts with [th]. Hindi-English bilinguals, however, when speaking English, regularly use Hindi /t/ and not/th/, where a “predictably” aspirated English/t/would be expected. For native English speakers, including linguists, this choice seems erroneous. Consistent with this choice by Hindi speakers, is the general opinion of many Hindi-speaking linguists that, contrary to the opinion of American linguists, English /p t k/are not aspirated. Labeling tests of edited naturally produced nonsense CV syllables yielded data showing that Indian and American linguists differ considerably in locating an inaspirate-aspirate boundary along the VOT dimension.