The spelling of the word "PANIX" can be explained through its phonetic transcription in the International Phonetic Alphabet (IPA). The first sound represented is /p/ which indicates a voiceless bilabial plosive. It is followed by /æ/ which denotes a low front vowel. Next, we have /n/ which stands for a voiced alveolar nasal. Finally, the last two sounds are /ɪks/ representing a voiceless velar fricative and a voiceless alveolar plosive, respectively. Therefore, the correct spelling of this word is "PANIX".