Struggling With Sibilants： Do English Speakers Use Acceptable Alternative Tongue Placements to Pronounce/s/and/z/？

Textbooks on phonology and on teaching ESL （English as a Second Language） often present the place of articulation of the sibilant/s/and its voiced counterpart/z/as a settled matter. The/s/and/z/are described and listed in phonological charts as ＂alveolar fricatives＂, meaning that the tongue is raised and the apex approaches the alveolar ridge. Those teaching pronunciation or remediating speech problems often use these descriptions by the IPA （International Phonetic Association） as models for teaching these phonemes. A number of linguists and instructors, however, have suggested that an acceptable/s/and/z/sound can be produced in English by other means This study attempted to determine the prevalence of the acceptable alternative placements for the/s/and/z/sounds in a sample of 50 English-speaking university students. Results revealed that 64% of participants used alternate tongue positions to that described in the literature as standard. Implications for speech pathology and ESL instruction are discussed.

Simultaneous measurements of aeroacoustic sounds and wall vibration for exploring the contribution of tooth vibration in the production of sibilant sounds/s/

In order to understand the contribution of teeth vibration to the production of sibilant/s/, the pre-sent study was designed to develop a method of simultaneously measuring aeroacoustic sounds and the vibration of an obstacle. To measure the vibration without disturbing flow, the Michelson interferometer was employed. The flow channel, which had an obstacle wall inside of it, was fabricated such that it morphologically mimicked the simplified geometry of the oral cavity. Given airflows at a flow rate of 7.5 × 10–4 m3/s from the inlet, aeroacoustic sounds were generated. A spectrum analy-sis of the data demonstrated two prominent peaks in the sound at 1,300 and 3,500 Hz and one peak in the wall vibration at 3,500 Hz. The correlation in peak frequencies between the sound and wall vibration suggests that the sound at 3,500 Hz was induced by the wall vibration. In fact, the sound amplitude at 3,500 Hz decreased when the obstacle wall was thickened, which increased its rigidity (p < 0.05, t-test). The experimental results demonstrate that the developed techniques are capable of measuring aeroacoustic sound and obstacle wall vibration simultaneously, and suggest the potential to pave the way for detailed analysis of the production of sibilant sounds /s/.

VOWEL CONTEXT,PLACE DIFFERENCE,AND THE PERCEPTUAL DISTINCTIVENESS OF SIBILANTS

Vowel contexts are shown to influence the perceived distinction of sibilants at different places,e.g.,with alveolar vs.palatal sibilants perceptually less distinct in the [_i] context than in the [_a] context This study investigates if this pattern holds across different sibilant place contrasts,e.g.,an alveolar-palatal contrast vs.an alveolar-retroflex contrast.Twenty-four listeners completed a speeded-AX discrimination task in which the stimuli were the sound pairs [si-ci][sa-ca][si-si][sa-sa],which aimed to access the relative psychoacoustic distinction of these pairs.The [si-ci] pair turned out to introduce a lower accuracy and a longer response time than the other pairs,with no response time difference among the other three.Assuming a longer response time to indicate less perceptual distinctiveness,the results confirm the observation in the literature that a [si-ci] pair is perceptually less distinct than a [sa-ca] pair;the lack of difference in [si-si] vs.[sa-sa] suggests that the[_i] context does not reduce the perceived sibilant place distinction across all places.There seems to be a trading relation between the effect of vowel context (e.g.,a reduced distinction in the [_i] context) and the relative acoustic difference between sibilants when evaluating the distinctiveness of a CV pair.

Evaluating the Role of International Trade in the Growth of China's CO_2 Emissions

International trade matters in assessing the extent of China＇s responsibility for CO2 emis- sions. A determining factor is whether emissions are measured in production or in consumption terms. Based on a series of input-output tables, an empirical analysis is conducted to measure the impact of international trade on China＇s emissions growth during the period 1997 to 2007. The authors also measure the impact on emissions of bilateral trade between China and US, European Union and Japan. As the largest of the developing countries, China has a trade surplus that can substantially influence its measured responsibility for emissions. The authors consider some policy implications for ihternational negotiations to reduce global greenhouse gas emissions.