[æ]’s original sound is [에]. The reason why it is heard like [아] is that its articulate point is very near [ɑ]’s. In other words, it is heard like [에]+[아]. Its pronuciation has been taught as [애] in Korea. In fact, [애](=[아]+[이]) is heard like [에]+[아]. Hoon Min Jung phonetics explained like this firstly in the world. Also, Hoon Min Jung phonetics explained about a vowel rectangle using ‘group theory’ in mathematics firstly in the world on August in 2009.