The spelling of the phrase "making up the top one head" may seem confusing, but it is actually quite logical when broken down phonetically. Each word is pronounced with its standard pronunciation, except for "top one," which is pronounced as /tɒp wʌn/. This is because, in spoken English, "one" can be reduced to a schwa sound, which is represented by the symbol "ʌ" in IPA. Therefore, the correct spelling of the phrase is "making up the top one head."