Comparison Between Esperanto and Ido - Phonology

Phonology

Ido omits two consonants used in Esperanto, /x/ and /d͡ʒ/, opting to use the similar sounds /h/ and /ʒ/ exclusively.

Ido's rule for determining stress is regular, but more complex than Esperanto's. In Esperanto, all words are stressed on the second-to-last syllable: radio, televido. In Ido all polysyllables are stressed on the second-to-last syllable except for verb infinitives, which are stressed on the last syllable—skolo, kafeo and lernas for "school", "coffee" and the present tense of "to learn", but irar, savar and drinkar for "to go", "to know" and "to drink". If an i or u precedes another vowel, the pair is considered part of the same syllable when applying the accent rule—thus radio, familio and manuo for "radio", "family" and "hand", unless the two vowels are the only ones in the word, in which case the "i" or "u" is stressed: dio, frua for "day" and "early".