# An Acoustic Way to Support Japanese Children's Effective English Learning in School Classrooms
## 1 Introduction  
English language education at Japanese public schools has been criticized. The average score of Test of English as a Foreign Language in Japan has been around the lowest among Organisation for Economic Co-operation and Development countries [1]. Many Japanese people cannot make a simple daily conversation in English after completing a compulsory six-year English language course in Japan [2]. In April 2020, the age to start teaching English at most Japanese elementary schools was officially lowered to resolve the matter. Grade three and four (age 8-10) have some English lessons to get familiar with the language, whereas grade five and six (age 10-12) learn English as a subject, thus their skills get evaluated through tests [3]. Previous research has shown evidence of poor acoustics found in school classrooms and their negative influence on children in various aspects [4, 5, 6, 7, 8, 9, 10]. Children are often too exhausted from trying to comprehend speech contents; subsequently they have littleenergy left to perform any cognitive tasks using the obtained information [11; 12]. Not only language related skills, such as reading, writing, speaking and listening, but also others, including numeracy, working memory and motivation of children were deteriorated as a consequence [13; 14; 15; 16; 17; 18; 19; 20; 21]. The further the distance between a speaker and a listener, the less speech is heard [22]. In a closed space like a classroom, sound reflection and absorption by the ceiling, floor, walls, furniture as well as people present, all integrate together with the sound directly emitted by a speaker to shape diverse characteristics of the sound field [23; 24]. Consequently, the intelligibility of a teacher's speech signals fluctuates depending on where children are, even in the same classroom [25]. However, such effects on human perception in real rooms of sizes often seen in classrooms are not well understood [26], compared to those in large indoor spaces for performance (e.g., concert halls and auditoria). The length of time in which children are required to listen to their teachers, peers, or audio materials accounts for the majority of learning time children spend in their classrooms [9], taking up to 45-75% in total [7; 27]. With the teaching style shift towards what is sometimes called \"active learning\" [28], children are demanded to listen more and more in classrooms that are noisier than ever. The introduction of more group work also leads to children's learning abilities being more linked with their hearing skills than ever [29]. It is also important to note that hearing in children is not as sophisticated as that in adults, especially in noisy environments [14; 30]. Thus, adults are often unable to perceive the hearing difficulties experienced by young children even in the same classroom [7; 31]. The way one speaks usually varies under noisy conditions. This, known as the \"Lombard effect\", is recognised to reduce intelligibility but also cause strains on speakers. Such deteriorated speech signals are inadequate for children to learn anything, especially languages [32; 33]. Moreover, for those aged between 5 and 15 years in particular, it is common to contract middle ear infectious disease Otitis Media, which causes temporary hearing loss of up to 40 dB hearing level and often lasts more than one months [8]. Many teachers have also expressed their discontent with poor acoustics at schools [6; 34; 35]. Teachers are more likely to report voice disorders than those in any other professions [34]. Absent teachers due to voice related health problems impose non-negligible costs. Since much information is delivered in speech form in classrooms, good acoustics there would benefit a much larger population than just children with already-diagnosed hearing impairments.