The phrase "am down the mouth" is not a commonly used expression in English, but its spelling can be explained using the International Phonetic Alphabet (IPA). The first word "am" is spelled /æm/ in IPA, which represents the short vowel sound "a" as in "ham". The next word "down" is spelled /daʊn/ in IPA, with the diphthong "ow" as in "cow". Finally, "the mouth" is spelled /ðə maʊθ/ in IPA, with the voiced "th" sound and the diphthong "ou". Together, the phrase is pronounced as "am doun the mawth".