本研究針對東勢客家話舌葉音聲母[t∫,t∫^h, ∫]進行社會語音學探究，藉以瞭解舌葉音聲母是否出現共時變異。六十名說東勢客家話的發音人參與本研究，依據性別、年齡共分成六組，每組十人。本研究透過發音人唸讀東勢客家話的發音字表、閱讀短文及國語的發音字表的方式收集語料，採用PRAAT測量擦音的「摩擦噪音時長」與「頻譜能量高峰頻率」，並對結果進行統計分析。本研究發現[t∫,t∫^h, ∫]依然維持著一組獨立的舌葉音聲母的地位。有趣的是，在「高前元音、年齡、性別、語體」等條件的影響之下，[t∫,t∫^h, ∫]呈現往[ｔ□,t□^h, □]變異的趨勢。最後，本研究從語言與社會觀點出發為這個變異趨勢提供合理的解釋。

This study sociophonetically explored the synchronic variation of laminal onsets [t∫, t∫^h, ∫] in Dongshi Hakka. Sixty speech informants, with Dongshi Hakka as their native language, participated in this study. They were separated into six groups according to gender and age. Speech data were collected by informants' reading a word list and a reading passage in Dongshi Hakka and a word list in Mandarin Chinese. PRAAT was used to measure frictional duration and spectral peak frequencies of fricatives [∫, □]. It has been shown in this study that laminal onsets [t∫, t∫^h, ∫] in Dongshi Hakka remained as an independent group of onsets. Interestingly, [t∫, t∫^h, ∫] tended to vary towards [t□, t□^h, □] under the effects of such factors as vowel, age, gender and register. Finally, this study offered explanations to this variation tendency from linguistic and social perspectives.