The acoustical study is the current study and the new methodology of scientific approach in Cambodia. The objective of acoustical study concerns with the descriptive features of vowels system in Khmer standardization with the articulation of vowels in the horizontal and vertical axis. In order to distinguish sound segment that is a clearly speak for acoustical measurement and analyse on acoustic software, we have to create the lexicon with 168 worlds list consist of all vowels sound segments that are the isolated words, and the words in the specific contexts of the phrases, “This word is pronounced that ………”, are 64 words and phrases.
In order to select the clearly sound by those speakers who are speaking accordingly by the grammatical rules of modern Khmer pronunciation among 21 informants, we had organized the informal conversation with them in several times and places before starting recording the selected informants. As the result, we found only four speakers, two males and females, who pronounced clearly and grammatically by the descriptive features in the modern Khmer pronunciation approaches. Finally, we brought them into our studio room, using the filter device on microphone and a computer program for recording the voice of all speakers by formal speech accessing and contextualization approach.
As soon as we recorded all informants accurately, we continued our measurements with the acoustical software for defining the formants, frequency one and two and the vowels pronounced duration. Then, we designed the vowels frequencies data entry on Microsoft Excel. In these processes, we analysed differently and classifiably by male speakers and female speakers. Although, female speakers and male speakers were not merged into the same data entry but we combined their average of frequencies, f1 and f2, into the descriptive features of international vowels chart entry and diagram. After that, we created the diagram by articulation of vowels features and identified the place of articulation by the acoustical features, frequency one by vertical axis and frequency two by the horizontal axis. As the result, we found that all female speakers were pronounced closer than male speakers on the short and long vowels. By the way, both male and female speakers were identified that all of short vowels were pronounced much more opened than their long vowels pronunciations. In addition, for vowels duration and articulatory of timing, we discovered that both male and female were pronounced by the most similar duration. The average of vowels durations were measured between 10 milliseconds to 30 milliseconds by long vowels data entries and between 0.6 millisecond to 11 milliseconds on short vowels data entries.
In conclusion, an acoustical study of Khmer vowels system is more consistently and functionally in the standardization approaches of every language includes Khmer vowels standardization. The main objectives of this study are more specified and functionalized approaches than the articulatory study of vowels system in general. As the matter fact, we are now discovered the new vowels model by the sound segments and frequencies approach on Khmer vowels system and built up the standardized structure and variation of speech science in the acoustical phenomena that followed the international phonetics vowels chart. Consequently, all of long vowels pronounced closer than short vowels by horizontal and vertical axis, f1 and f2. The vowel, place of articulation is structured on the rule of international vowels chart by its number and scale. Furthermore, vowels duration are similar in both long and short but it has a complicated timescale of vowels in the onset file. All duration were measured twice in order to get more accurately and acoustically.
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