1.2 Purpose of the research

    The purpose of this study was to explore what kind of role teacher’s English speech plays, how Chinese thinking patterns, teacher’s expressions, students’ psychological states and shared language/knowledge background influence the interlanguage speech intelligibility for junior middle school students.

1.3 Structure of the thesis

The first chapter briefly introduces the importance of understanding the language and some factors that contribute to language comprehension which have already been studied. Meanwhile it defines the direction, scope, content, and mission of the research. The second chapter summarizes the factors that influence language comprehension that are relevant to this study. The factors of the research will be pided into two categories: non-linguistic factors and linguistic factors. Non-linguistic factors include visual stimulus, reverberation time and so on. Linguistic factors include accent, language proficiency, teacher talk and China English. There is a brief summary of this chapter at the end. The third chapter is about research methods: experimental design, material preparation, participants selection, experimental procedures, data collection and data analysis. The last chapter summarizes the experimental results, implications for English teaching, the limitations of the experiment and the prospect of further research.

 2 Literature review

2.1 Non-Linguistic Factors

2.1.1 Visual Stimulus

Koppen and Spence (2007) and Sinnett et al. (2007) and Sinnett et al. (2008) confirmed the effect that when two stimuli were presented simultaneously, all subjects pushed the button for visual stimulus. Because of the full potential of visual signals, many experiments related to the capacity of attention have so far focused on visual signals (Plack, 2010). What’s more, some specific researches found that typical laryngeal listeners have demonstrated a greater reliance on visual information as auditory distortion is increased (Benoit et al., 1994 ; Sanders and Goodrich, 1971).

Nelson and Hodge (2000) evaluated the effects of visual information on a speaker with bilateral facial paralysis. Results showed that listeners had no difficulty identifying the placement of stop consonants in both the auditory-only and auditory–visual conditions for the typical speech stimuli. However, listeners did have difficulty identifying the location of stop consonants in both the auditory-only and the auditory–visual presentation modes for the speaker with bilateral facial paralysis. It is more likely that reductions in speech intelligibility seen with the inclusion of visual information are related to the role of the listener. Listeners tend to recruit more visual information as the acoustic information becomes more degraded or ambiguous (Kenitz et al., 2007; Massaro, 1987). This finding is bolstered by recent neuro imaging data showing that listeners increase their attention to visual information when presented with degraded auditory stimuli (Kawase et al., 2005).

2.1.2 Others

The ability to communicate effectively within a classroom also depends on a few basic elements: appropriate reverberation time (RT), signal-to-noise ratio (SNR) and appropriate speech sound pressure level (SSPL) (Subramaniam, Ramachandraiah, 2006). Poor acoustical conditions reduce speech intelligibility in classrooms and affect attention and academic performance of students (Jiang, 1997). There have been many published studies of acoustical conditions in classrooms and most of them related to RT, background-noise level (BNL) and SNR (Picard, Bradley, 1986, 2001; Bistafa, Bradley, 2000; Hodgson, Rempel, Kennedy, 1999; M. Hodgson, E. Nosal, 2002). Bradley, Hodgson and their colleagues investigated the relationship between these factors and speech intelligibility by carrying out a series of experimental and theoretical studies in classrooms. They pointed out that noise is the more critical factor and that criteria for acoustical conditions in the classroom should be based upon speech intelligibility. In work with adult listeners, Bradley et al. (1999) found that the effect of SNR is much more important than that of reverberation in understanding speech while room acoustical characteristics and SNRs both influence speech intelligibility in rooms. Using eye-gaze tracking equipment, Buchan, Pare, and Munhall (2007) studied listener eye-gaze when presented with video stimuli of a speaker producing sentences in varying SNR's. Listeners focused their gaze on the nose, mouth, and eyes of the speaker during high SNR's but focused their gaze almost exclusively on the mouth of the speaker during low SNR's. A high speech intelligibility is possible even in conditions where the energy of interfering noise is several times greater than the energy of the speech signal (Duquesnoy, 1983; Festen and Plomp, 1986; Gustafsson and Arlinger, 1994; Kocinski and Sek, 2005; Ozimek et al., 2013 ; Plomp, 1976). It must be emphasized that,源Z自+吹冰=文)论(文]网[www.chuibin.com  in a natural environment, beside a speech signal, many other signals that involve other senses and attention occur simultaneously. These so-called distracters can influence our ability to process a speech signal correctly.