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Article Excerpt
The aim of this study was to examine the effects of sound-field amplification intervention on the acquisition of specific educational goals for children in mainstream cross-cultural classrooms. Twelve classes of Year 2 children participated in the project. For classes 1 to 8, the listening environments were alternated between amplified and unamplified conditions, each condition being for two terms (one semester) of the school year. Beneficial effects of amplification were obtained in all three skill areas of reading, writing and numeracy. The beneficial effects occurred irrespective of whether the children had English as a native language or as a second language. Classes 9 to 12 were alternated between single-channel and dual-channel transmission options, each condition being for one semester of the school year. The results indicated that using different numbers of microphones did not affect the rate of acquisition of educational outcomes.
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The goal of classroom instruction is comprehension. In order for speech to be comprehended, the individual must be able to hear well enough to discriminate the word-sound distinctions of individual phonemes (Robertson, 2000). Normal hearing for children is 15 dB HL or better at all frequencies, and with normal middle ear function (Northern & Downs, 1991). A minimal or slight hearing loss extends from 16 dB HL to 25 dB HL (Clark, 1981). As noted by Flexer (1995), the prevalence of these lesser but educationally significant hearing losses is underestimated. Poor comprehension in the classroom is not, however, limited to those with hearing loss.
Acoustical factors affecting classroom communication
In a review of children at risk of poor comprehension in the classroom, Nelson and Soli (2000) concluded that young listeners perform more poorly in noisy situations than do adults, and the ability to listen when surrounded by noise is not fully developed until adolescence (Stelmachowicz, Hoover, Lewis, Kortekaas, & Pittman, 2000). Additionally, a child's auditory brain is not like an adult's until about the age of 15 (Chermak & Musiek, 1997). Therefore, children cannot rely on years of language and learning experiences to fill in the gaps of missed information.
The combination of excessive noise and reverberant classrooms contributes to the difficulties faced by all school children in understanding the teacher's verbal instruction (Crandell & Smaldino, 2000). Flexer (2002) referred to a national acoustical standard recently adopted in the United States (ANSI, 2002), which calls for classroom noise levels to be less than 35 dBA, and reverberation time (RT) to be less than 0.6 seconds for medium-size rooms and 0.7 seconds for larger-size rooms.
Numerous studies have found recommended acoustical standards are not achieved in the majority of classrooms (Crandell, Smaldino & Flexer, 1999). Noise levels in unoccupied primary school classrooms typically range from 41 to 51 dBA (Bess, Sinclair & Riggs, 1984; Crandell & Smaldino, 1994). Other investigations have reported noise levels in occupied primary school classrooms ranging from 52-62 dBA (Crandell & Smaldino, 1995) to 65-69 dBA (Pekkarinen & Viljanen, 1991).
Communication in cross-cultural classrooms
Adult individuals for whom English is a second language (ESL) experience greater speech perception difficulties in difl]cult listening environments than native English listeners (Crandell & Smaldino, 1994; Nabelek & Nabelek, 1994). Researchers have noted the implications this may have for non-native English-speaking children who are listening in poor classroom acoustic environments (Burnip, 1994; Crandell, 1991; Crandell & Bess, 1986; Crandell & Smaldino, 1996). Nilsson, Gellnet, Sullivan and Soli (1992) found that the ability to understand spoken English in noise is related to the individual's proficiency with the English language. When examining the speech perception of 20 native English-speaking children and 20 ESL children, Crandell and Smaldino (1996) found the ESE children's performance was significantly poorer across most classroom listening conditions.
Cultural differences, language differences and different learning styles also contribute to the difficulties facing teachers and children (Eriks Brophy & Crago, 1994; Howard, 1991; West, 1994). In an ethnographic study with Inuit school children, Eriks Brophy and Crago (1994) emphasised the peer group as being an integral part of the building of 'classroom talk', and identified the facilitation of peer exchanges as one of the most important roles in the classroom.
Sound-field amplification
Sound-field amplification is an educational tool that increases control of the acoustic environment in a classroom, thereby facilitating acoustic accessibility to teacher instruction for all children in the room (Crandell, Smaldino & Flexer, 1995). Through the use of loudspeakers, the teacher's voice is transmitted from a microphone to a receiver and amplified evenly throughout the classroom. Originally designed as an assistive technology for children with mild hearing loss, research over the past 20 years has shown that the benefits of sound-field amplification include improved academic achievement, speech recognition, attending skills, and learning behaviours (Rosenberg & Blake-Rahter, 1995). These authors provide an extensive review of the earlier literature.
Recent studies have consolidated the view that sound-field amplification technology enhances classroom learning. In 1999, Rosenberg et al. reported on a three-year project involving general education kindergarten, first and second grade classrooms. Their findings indicated that students in amplified classrooms demonstrated improvement in listening and learning behaviours, and progressed at a faster rate than their grade-alike peers in unamplified classrooms. Other recent study findings include the following: Long and Flexer (2001) cited a reduction in special education referrals by almost half for children in kindergarten through to fifth grade classrooms; Darai (2000) found that first grade students in classrooms with sound-field systems achieved greater literacy gains compared to control students; Flexer (2000) demonstrated improved reading test scores for first grade children, 85 per cent of whom were Native American; Flexer, Kemp Biley, Hinkley, Harkema...
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