Esperanto inventory

The original Esperanto lexicon contains 23 consonants, including 4 affricates and one, /x/, which has become rare; and 11 vowels, 5 simple and 6 diphthongs. A few additional sounds in loan words, such as /ou̯/, are not stable.

Consonants

		Labial	Alveolar	Postalveolar	Palatal	Velar	Glottal
Nasal		m	n
Plosive	voiceless	p	t			k
	voiced	b	d			ɡ
Affricate	voiceless		t͡s	t͡ʃ
	voiced		(d͡z)	d͡ʒ
Fricative	voiceless	f	s	ʃ		(x)	h
	voiced	v	z	ʒ
Approximant			l		j	(w)
Trill			r

The uncommon affricate /d͡z/ does not have a distinct letter in the orthography, but is written with the digraph ⟨dz⟩, as in edzo ('husband'). Not everyone agrees on its status as a phoneme; Wennergren considers it as a simple sequence of d + z. The phoneme /x/ has been largely replaced with /k/ and is a marginal phoneme mostly found in loanwords and proper names such as ĉeĥo ('a Czech') vs ĉeko ('a check'). The voiced labio-velar approximant /w/ is normally only encountered as the second element of diphthongs (see below), although it is sometimes used consonantally in onomatopoeia and in foreign names.

Vowels

	Front	Back
Close	i	u
Mid	e	o
Open	a

There are also six historically stable diphthongs: /ai̯/, /oi̯/, /ui̯/, /ei̯/ and /au̯/, /eu̯/. However, some authors such as John C. Wells regard them as vowel + consonant combinations (/aj/, /oj/, /uj/, /ej/, /aw/, /ew/), while Wennergren regards only the latter two as diphthongs.

Slavic origins

This inventory is rather similar to that of Polish, but is especially close to Belarusian, which was historically important to Zamenhof, the creator of Esperanto. The essential difference from Belarusian (and Polish) is the absence of palatalization, although this was present in Proto-Esperanto (nacjes, now nacioj 'nations'; familje, now familio 'family') and arguably survives marginally in the affectionate suffixes -njo and -ĉjo, and in the interjection tju!. Minor differences are that g is pronounced as a stop, [ɡ], rather than as a fricative, [ɣ] (in Belarusian, the stop pronunciation is found in recent loan words); a distinction between /x/ and /h/; and the absence of a diphthong oŭ /ou̯/, though that was added to Esperanto to a minor degree after its creation. Like Belarusian, /v/ is found in syllable onsets and /u̯/ in syllable codas; however, unlike Belarusian, /v/ does not become /u̯/ if forced into coda position through compounding, though Zamenhof avoided such situations by adding an epenthetic vowel: lavobaseno ('washbasin'), not *lavbaseno or *laŭbaseno.

External links

• Esperanto phonology