Stop Consonant Characteristics: VOT and Voicing in American-Born-Indonesian Children’s Stop Consonants

The increasing number of Indonesian immigrants in the United States suggests the need for deeper understanding of English acquisition as a second language by Indonesian children and their adult caregivers. Unfortunately this language‟s interaction with English as an L2 (particularly in terms of language interference) is currently understudied. This study examines the acquisition of English stop consonants by typically developing Indonesian bilingual children and their parents. Thirteen pairs of parent-child Indonesian bilingual speakers produced six stop consonants (/p/, /t/, /k/, /b/, /d/ and /g/) common in both languages in word-initial position with a variety of vowels. Pictures representing these words were shown on a computer monitor and speakers were asked to say the word in the context “That‟s a ___” for English words and its equivalent “Itu ___” for Bahasa Indonesia words. The phonetic characteristics of voice onset time were the focus of this study. The prediction is that the children‟s production of English stops from both subject groups will have similar acoustical characteristics. However, their parents‟ production will have different acoustical characteristics because of the influence of the age of learning a second language. The findings of this study will enable us to learn more about first and second language acquisition among bilingual children. Stop Consonant Characteristics 7 List of Tables Table 1. Subjects‟ gender, birth country and home language preferences. 14 Table 2. Children‟s ages . 15 Table 3. Result of voicing categories across speakers. 23 Table 4.Mean VOT across speaker types. 24 Table 5.Closure duration across speaker types for voiced and voiceless stops. 26 Table 6. Mean VOT based on home language preferences for Indonesian adults. 27 Table 7. Mean closure duration based on home language preferences for Indonesian adults. 27 Table 8. Mean VOT based on home language preferences for voiced and voiceless stop consonant for Indonesian children. 28 Table 9. Mean closure duration based on home language preferences for voiced and voiceless stop consonants for Indonesian children. 29 Stop Consonant Characteristics 8 List of Figures Figure 1. Sample of an English stimulus . 17 Figure 2. Markers for calculating VOT and closure duration. 19 Figure 3. An example of no voicing on a spectrogram . 20 Figure 4. An example of pre-voicing on a spectrogram . 20 Figure 5. An example of complete voicing on a spectrogram . 21 Figure 6. An example of partial voicing on a spectrogram. 21 Figure 7. Mean VOT across speaker types . 25 Figure 8. Mean closure duration across speaker types . 26 Figure 9. Mean VOT for each consonant across speaker types . 30 Stop Consonant Characteristics 9 Chapter 1: Introduction The increasing number of bilingual children in the United States of America requires careful examination that looks into their language acquisition. The native language (L1) one learns in early childhood and a second language (L2) learned later in life often influence one another (Flege, 1991). Therefore, it is important for speech language pathologists to be aware of these differences in phonetic characteristic of bilingual children. Adequate knowledge about speech development in normal developing children from culturally and linguistically diverse background will enable speech language pathologists to work more effectively. Currently, there are an increasing number of Indonesian immigrants in America. The majority of them settled and immigrated to the United States after finishing their college education. Indonesia is the fourth most populous country in the world and home to the largest Moslem population in the world (The World Factbook, 2009). Therefore, Bahasa Indonesia and its related dialect, Bahasa Malayu, is the most widely spoken language in Southeast Asia. Unfortunately, there is little phonetic research in the Indonesian language in general and even less in term of the acquisition of English by Indonesian children who were born in America. Many of these children grew up in a home environment in which both parents are Indonesian native speakers and late English learners. Therefore, these parents have distinct accent in their English pronunciation. One distinct pronunciation that can be seen is the pronunciation of stop consonants. This study seeks to examine the phonetic characteristics of Indonesian children‟s stop consonants pronunciation as compared to their Indonesian parents and American English monolingual children. Specifically these three questions will be addressed. Stop Consonant Characteristics 10 1. What are the mean VOT values of Indonesian children and adults who participated in this study. 2. How and to what extent the VOT characteristics of English stop consonants production differ between children who have Indonesian parents and monolingual native American children. 3. What are the possible contributing or determinant factors that make their pronunciation differ. Unfortunately, there is no previous study that examines the same questions. Therefore, this study will serve as a starting point in attempt to understand the pronunciation of word-initial English stop consonants by Indonesian children primarily by analyzing voice onset time (VOT) of (/p/, /t/, /k/, /b/, /d/, /g/) pronounced by Indonesian children ages 2-9 years old. The result of mean VOT values for those stop consonants in English will be compared to mean VOT values of the same stop consonants in Indonesian language in a later study. Stop Consonant Characteristics 11 Chapter 2: Literature Review There are some basic differences in Bahasa Indonesia and English stop pronunciation. In Bahasa Indonesia, /p/, /t/, and /k/ are pronounced without a release of air (aspiration). On the contrary, in the “standard” American English those consonants are pronounced with aspiration. Therefore, it is predictable that aspiration in these voiceless English stops will present problems for Indonesian speakers who are learning English. Most likely, Indonesian speakers will say /p, t, k/ in English also without the expected aspiration. There are also place of articulation differences for stops between the two languages. The stops /t/ and /d/ are dental sounds made with constriction between the tip of the tongue and the upper teeth in Bahasa Indonesia. However, English pronunciation of /t/ and /d/ is alveolar meaning the blade of the tongue is on the alveolar ridge (just behind the upper teeth) (Soderberg, 2008). Stop consonants are the most common consonants in both pre-linguistic and early linguistic development regardless of a child‟s ambient language community (Kim & Gammon, 2010). In addition, more than 88% of languages use voicing to differentiate homorganic stops by exploiting three major timing relationships: lead voicing, long lag and short lag (MacLeod & Gammon, 2005). For the last five decades, VOT (voice onset time) has been used by researchers to measure the timing relationships that makes the distinctions among these three categories. VOT The important role of VOT to categorize stop consonants in a language was first proposed by Lisker and Abramson in 1964. VOT is defined as the temporal relation between the onset of glottal pulsing and the release of the initial stop consonant (Lisker & Abramson, 1964). Stop Consonant Characteristics 12 It is the length of time between the released of stop consonant to the start of voicing. VOT value can be negative when voicing start prior to consonant release. In order to measure the VOT value, the point of stop released and voicing must be determined. In their study, Lisker and Abramson examined stop consonants data from 11 languages. They categorized stop consonants into 3 categories: lead, short lag and long lag. Those categories are differentiated by VOT values. Long lead is a category in which voicing start about 75-125 ms before the release of consonant (negative value VOT). Short lag is when voicing start 0-25 ms after the release. Long lag is when voicing start 60-100 ms after the release. (Lisker & Abramson, 1964). Previous research has established that late learners are apt to produce English /p, t, k/ with VOT values that are too short for English (Flege, 1991). It would be interesting to see whether this condition would be true for Indonesian adult speakers in this study. In addition, it would be interesting to observe the possible differences that may occur. Voicing Another dimension that linguists use to distinguish stop consonant is “voicing. ” Voicing is defined as the vibration of vocal cords. Therefore there is a presence of vibration when voiced consonants are being produced and there is an absence of vibration when voiceless consonants are being produced. Bahasa Indonesia has similar stop consonant voicing contrast to English. Both languages have voiced and voiceless stop conson