When he talks about his favourite subject, the tone of his voice changes
「声のトーンが変わった」＝ The tone of his voice changed / He changed the tone of his voice / When he talks about his favourite subject, the tone of his voice changes※女性の場合、「he」ではなく「she」にしてくださいね＾＾ボキャブラリーtone of 人's voice ＝ 声のトーンchanged ＝ 変わったwhen ＝ ～の時talk about ＝ ～について話すfavourite subject ＝ 好きな話、好きなテーマ
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