A tool is proposed to reinforce the pronunciation of vowels and consonants for the instruction of adult learners in Costa Rica. A critical review of literature on approaches to teaching vowels and consonants is followed by a comparative discussion of two transcription systems: that of the International Phonetic Association, and those found in textbooks, dictionaries and pronunciation websites. This is complemented by a brief comparison of English and Spanish vowels and consonants, and descriptions of common pronunciation challenges for Spanish speakers. Open problems are explored, as are ethical reflections on the teaching of English pronunciation.