The spelling of "per bak" can be explained using the International Phonetic Alphabet (IPA). Each letter in the word has a specific phonetic symbol that represents its sound. "Per" is pronounced as /pɜr/, with the "e" sound being a schwa sound similar to "uh." "Bak" is pronounced as /bak/, with a short "a" sound and a hard "k" sound. The combination of these sounds creates the unique pronunciation of "per bak." It is important to use the correct spelling and pronunciation for clear communication.