The solution is the transcription in IPA (International Phonetics Alphabet), which is used in linguistics works, in dictionaries and in language text books from secondary school to university.
"The International Phonetic Alphabet (IPA) is a system of phonetic notation devised by linguists to accurately and uniquely represent each of the wide variety of sounds (phones or phonemes) used in spoken human language. It is intended as a notational standard for the phonemic and phonetic representation of all spoken languages."http://en.wikipedia.org/wiki/International_Phonetic_Alphabet
It is very very useful.
(In Catalonia, secondary school pupils have the IPA and the transcription of texts in IPA as subject in language courses, usually in Catalan courses, but applied to Spanish and English, too.)