Speech is a complex acoustic signal that contains both linguistic and paralinguistic information. Linguistic information includes segmental and suprasegmental as well as lexical, grammatical, and semantic features. Paralinguistic information contains extralinguistic cues that serve to identify speaker characteristics such as age, gender, voice quality, emotional state, and physical state (Abercrombie, 1967). Both sources of information (linguistic and paralinguistic) play a critical role in the perception of speech by listeners. The present study addressed the effect of extralinguistic information (speaker's gender) and prosodic information (word length) on the perception of speech by children.
EFFECT OF AGE ON SPEECH PERCEPTION
Many previous studies have examined the effect of age on various aspects of speech perception (e.g. acoustical cues, phonemes, words). Many of these studies compared the performance of young children to that of adults and reported that children are less sensitive to perceptual cues than adults (Elliott, 1986; Elliott, Longinotti, Meyer, Raz, & Zucker, 1981; Elliott & Hammer, 1988; Sussman & Carney, 1989; Sussman, 1993; Morrongiello, Robson, Best, & Clifton1984; Nittrouer & Studdert-Kennedy, 1987). For example, Ryalls and Pisoni (1997) investigated the effect of talker variability on word recognition. They found that children between the ages of 3 to 5 years were less accurate than adults at identifying words produced by multiple speakers than those spoken by a single speaker, regardless of whether the words were produced in quiet or in noise. Another set of these studies compared speech perception of children across different ages and adults. For example, Hazan & Markhan (2004) compared the performance of 7- to 8-year-olds with 11- to 12-year-olds and with a group of adults. They found that the 7- to 8-year-olds made significantly more errors than the 11- to 12-year-olds and the adults in a word recognition task with background noise. Drager, Clark-Serpentine, Johnson, and Roeser (2006) investigated the perception of words and sentences in background noise by children aged 3 to 5 years. They reported that the 3-year-olds performed more poorly than the 4- and 5-year-olds. These researchers used synthesized words and sentences that were digitized using the speech of an 11-year old female speaker.
Some researchers claim that the poorer performance of children in comparison to adults is due to the children's immature sensory processing in either the peripheral or central auditory systems for both speech and nonspeech auditory stimuli (Elliott, 1986; Elliott et al., 1981; Hall & Grose, 1991; Sussman & Carney, 1989). Other investigators claim that it is the inability of younger children to attend selectively to the task at hand that limits their performance (Allen, Wightman, Kistler, & Dolan, 1989; Morrongiello et al., 1984; Wightman, Allen, Dolan, Kistler, & Jamleson, 1989). Allen et al. (1989) concluded that processing efficiency (i.e., the ability to filter interfering noise), frequency resolution and listening performance are abilities that improve with age. Thus, better listening performance is due to maturation of the central nervous system. In other words, increasing age improves the ability to allocate the attentional mechanism.
Some studies have suggested that the type of task used will determine the age at which children will demonstrate adult-like speech perception performance. For example, when the task requires discrimination of temporal and frequency cues, performance does not become adult-like until the age of 10 to 11 years (Allen & Wightman, 1992; Sussman & Carney, 1989). However, when the task is an identification one, adult-like performance for speech sounds occurs earlier, (i.e., at about 6 years of age) (Sussman & Carney, 1989; Walley & Carrell, 1983).
EFFECT OF GENDER ON SPEECH INTELLIGIBILITY AND SPEECH PERCEPTION
Male and female glottal characteristics differ considerably (Han-son, 1995; Klatt & Klatt, 1990), and listeners are generally able to distinguish male from female voices quite easily (Nygaard, Sommer, & Pisoni, 1994; Tielen, 1992). …