Modern Evolution of Esperanto - Phonology

Phonology

The most visible change in Esperanto phonology has been the near-loss of the sound ĥ. For example, the German-derived word ĥino "Chinese" has been replaced by an Italian/English ĉino. In most other cases, ĥ has been replaced with k, as in kemio for ĥemio "chemistry"; a couple of the few words which commonly retain it are ĉeĥo "Czech", eĥo "echo" and ĥoro "chorus", though it continues to be used in the transcription of foreign names. See Esperanto phonology#Loss of phonemic ĥ, and the section preceding that for examples of assimilation which do not affect the written language.

Changes in phonotactics, which was never laid out explicitly by Zamenhof, have been introduced along with new vocabulary and especially foreign names. One of these is the extension of ŭ, which originally was only found as a vowel in the diphthongs aŭ and eŭ, to a consonantal use analogous to English w, which Zamenhof had universally replaced with v. However, Slavs and Germans, among others, have difficulty distinguishing v and consonantal ŭ, and in most neologisms, consonantal ŭ has been replaced with v, as it has in ŭato → vato "Watt". In proper names, such as Ŭakajama ~ Vakajama "Wakayama", there is more variation. Similarly, new ŭ diphthongs such as oŭ have not gotten far; the English word bowl was adopted as bovlo, not *boŭlo.

Another debated change has been the introduction of geminate consonants. In traditional Esperanto, double consonants may occur across morpheme boundaries, as in mallonga (mal-longa) "short", but are not found within roots. Most words introduced with double letters (including tĉ and dĝ) have since been modified, for example Buddo → Budao "Buddha". Perhaps the most common root to retain a double consonant is finno "Finn", which is a near homonym with fino "end". Although suomo has been introduced as a replacement, this has not been used for compounds such as finno-ugra "Finno-Ugric". There is considerable debate whether departing from the international forms of such words is desirable.