Co-articulated consonant consonant such as is doubly or secondarily articulated. In some English dialects, for example, is a labialized velar that could be transcribed as , but the Japanese is closer to a true labial-velar, . It is common usage to restrict the letter to the former. The glottis controls phonation, and works simultaneously with many consonants. It is not normally considered an articulator, and an ejective such as , with simultaneous closure of the velum and glottis, is not normally considered to be a co-articulated consonant. Co-articulated consonant Co-articulated consonants or complex consonants are consonants produced with two simultaneous places of
Speech perception been called vocal tract normalization (see Figure 3 for an example). Similarly, listeners are believed to adjust the perception of duration to the current tempo of the speech they are listening to – this has been referred to as speech rate normalization. Whether or not normalization actually takes place and what is its exact nature is a matter of theoretical controversy (see theories below). Perceptual constancy is a phenomenon not specific to speech perception only; it exists in other types of perception too. Categorical perception is involved in processes of perceptual differentiation. People perceive speech sounds categorically, that is to