Here are some of the reasons why hVd words have been used in many studies:
1. Much research on vowel perception has been done on English, where vowels in this context form real words. Although some of these words are rarely used, they are at least still recognizable by most speakers. This simplifies an experiment setup.
2. /h/-onset words do not contain appreciable formant transitions from the initial consonant. /h/ is mostly a de-voiced version of the upcoming vowel sound, so the formants are essentially unchanged. With other consonants, there would be initial formant transitions that could affect vowel perception (there is some literature out there about this).
3. One of the most widely cited papers on vowel acoustics in English (Hillenbrand et al., 1995 in JASA) used hVd words, so comprehensive acoustic data is available for those who want to synthesize these words or compare them in some way. Additionally, the first author of that paper has made the recordings and measurements from that study available (on his website) for people to use, so it’s a ready-made set of sounds and data.
There are probably other more technical reasons for using these words (as well as disadvantages, such as potentially not capturing the characteristics of “short” English vowels that come before voiceless sounds), but these are the first that spring to mind.
I would appreciate your help on the following question.
Q. In many of the vowel perception experiments, researchers have studied vowel perception in /hVd/ context. Why the vowel perception is studied in this (/hVd/) context? While studying vowel perception what other contexts can be used? And what are the difficulties that may be faced in other contexts (if any)?
Thank you so much in advance,