2a.A consonant is a speech sound produced by either closing or constricting(压缩)the vocal tract (声道) 2b.A speech sound produced by either closing or constricting the vocal tract is called a consonant.n 2a. A consonant is a speech sound produced by either closing or constricting（压缩） the vocal tract （声道）. n 2b. A speech sound produced by either closing or constricting the vocal tract is called a consonant