(excerpted from the Forward of the Esperanto dictionary by John Wells)
Since the Esperanto orthography is phonetic, every word is pronounced just as it is spelt; there are no silent letters.
Word stress in polysyllables always falls on the last syllable but one.
Esperanto vowels are pure (i.e., monophthongal), not diphthongal like most English long vowels. There is no distinction of length in vowels such as exists in English, but vowels in stressed syllables are usually rather longer than other vowels, particularly if the stressed syllable contains no consonant after the vowel. Thus the e in BEno is usually longer than the e in BENdo.
As against the twelve monophthongs of English, Esperanto has only five. They are comparable to the vowels of Spanish, Serbo-Croat, or Modern Greek.
i is a close front unrounded vowel, like English i in 'machine'. Do not centralize it and make it like i in 'thin'. Do not dipthongize it like popular London or Australian i in 'machine'.
e is a half-close/half-open front unrounded vowel, like English e in 'get'. Do not dipthongize it like a in 'cake'.
a is a open front/central vowel, further forward than English a in 'father'. Do not make it like a in 'cap', 'what', or 'water'.
o is a half-open back rounded vowel, like English o in 'forty', 'bought'. Do not make it like o in 'code'.
u is a close back rounded vowel somewhat like English oo in 'moon'.
It is wise to take particular care when a vowel appears before r; it is pronounced just the same in this position as any other. Esperanto perdo and burdo do not rhyme, even though English words such as 'kerb' and 'curb' are pronounced identically.
Words such as indigniĝis, severe, haltadas, kontrolon, susuru may be used for practice in keeping the sound of each vowel constant in spite of different surrounding sounds.
The semi-vowels j and ŭ are like English y and w. Thus j is a gliding non-syllabic i-sound, and ŭ is a gliding non-syllabic u-sound. They combine with preceding vowels to perform diphthongs.
aj represents a plus a short i-sound; it is like English y in 'my'.
aŭ represents a plus a short u-sound; it is like English ow in 'how'.
ej represents e plus a short i-sound. It is like English ay in 'play'
eŭ represents e plus a short u-sound. There is no corresponding English diphthong.
oj represents o plus a short i-sound. It is like English oy in 'boy'.
uj represents u plus a short i-sound. There is no corresponding English diphthong, but compare ui in ruinous, bluishness.
Vowels in unstressed syllables should be pronounced clearly and not reduced to a central quality. Preter is quite different from preta.
The Esperanto consonants should present very little difficulty to English-speaking people. The plosives, p,t,k,b,d,g are as in English (g always as in 'ago'), the fricatives f,v,s,z,ŝ,ĵ are like English f,v,s (always as in fussy), z (always as in fuzzy), sh, and zh (i.e., the s in 'measure') respectively; the affricates ĉ and ĝ are like English ch and j; the nasals m and n are as in English; so is h.
The voiceless alveolar affricate c is like English ts; unlike ts, though, it often begins a syllable (e.g., cepo). Where it occurs in clusters (penco, akcepti, sankcio, nescio, scias) it should be carefully practiced. Thus nescio has the same sequence as 'best seat' (with the t of 'best' neither elided nor realized as a glottal stop).
The sound of written ĥ is a voiceless velar fricative, like ch in Scots loch. It is a rare sound in Esperanto. The semi vowel j has been treated above; when before a vowel it is like English y, a voiced palatal frictionless continuant or fricative.
The liquids l and r should be carefully pronounced, and never weakened into vowel sounds as may happen in English. The lateral continuant, l, should be clear (as in 'leaf') rather than dark (as in 'feel'). If possible r should be pronounced as a lingual trill or tap (like the sound used in Italian or Russian). English people should be particularly careful not to omit it when it precedes a consonant; karto must not be pronounced as kato.
The voiced plosives, fricatives, and affricate (b,d,g,v,z,ĵ,ĝ) should be fully voiced in all positions.