A monophthong is a single, pure vowel sound. While pronouncing a monophthong, the positions of the mouth and tongue remain fixed. A diphthong is a vowel sound that changes from the beginning to the end, while still being pronounced in the space of a single syllable. While pronouncing a diphthong, the positions of the mouth and tongue change, or slide, from the beginning to the end of the vowel sound.
Both English and Italian contain both monophthongs and diphthongs. However native English speakers are often unaware of the distinction between these two types of vowel sounds because English spelling usually doesn’t give you very obvious clues about which type of sound is used in a particular word. In fact, in some instances the exact same word is pronounced with a monophthong in one variety of English and a diphthong in another. In contrast, Italian makes a very clear distinction between monophthongs and diphthongs. Monophthongs are always represented by a single written vowel and diphthongs are always represented by two written vowels. In order to develop an accurate Italian pronunciation it’s vital that you understand the difference between monophthongs and diphthongs and that you are able to always use the correct type of vowel sound.
English diphthongs
First we’re going to show you some examples of monophthongs and diphthongs in English. Please keep in mind that there are many different varieties of English that use different vowel sounds, so these examples may not all be valid for your particular variety of English. These examples are based on a standard Australian accent. The vowel sounds are represented using the International Phonetic Alphabet (IPA).
Monophthong
Example
Diphthong
Example
æ:
man
æɪ
main
ɪ
bit
ɑɪ
bite
ɔ
lot
əʉ
low
o:
tall
oɪ
toy
Italian diphthongs
Now we’ll turn to Italian vowels. In Lesson 1 we showed you the seven basic Italian vowel sounds. These sounds are all monophthongs, or pure vowel sounds, and they are always represented using a single written vowel. In contrast, diphthongs are always represented using two written vowels, and they are pronounced more or less as written - you start by pronouncing the first written vowel and then slide to the second written vowel.
When discussing diphthongs it helps to classify the vowels as strong vowels (a, e and o) and weak vowels (i and u). The strong vowels require the mouth to be more open than the weak vowels and this affects the way diphthongs and syllables can be formed. Essentially, each strong vowel must be pronounced in its own separate syllable - two strong vowels cannot be pronounced together in one syllable as a diphthong. A weak vowel, in contrast, may combine with a neighbouring vowel to form a diphthong (although it doesn’t have to). It follows, therefore, that a diphthong always consists of a strong vowel and a weak vowel or two weak vowels. When pronouncing a diphthong, the strong vowel, if present, always gets more emphasis. If the diphthong consists of two weak vowels then the second vowel gets more emphasis.
Following are examples of all the diphthongs that actually occur in Italian words. We’ve divided them into two categories: those that start with a weak vowel and those that start with a strong vowel. The diphthongs that start with a weak vowel can be either short or long and the second half of the diphthong gets more emphasis.
diphthong
example (long)
example (short)
ia
chiave
fianco
ie (closed)
niego
bietta
ie (open)
miele
niente
io (closed)
biodo
piombo
io (open)
piove
fiocco
iu
fiume
più
ua
quale
guanto
ue (closed)
quesito
quello
ue (open)
loquela
seguente
ui
guida
anguilla
uo (closed)
acquoso
buongiorno
uo (open)
buono
buon
The diphthongs that start with a strong vowel are always long and the first half of the diphthong gets more emphasis.
diphthong
example
example
ai
mai
laico
ei (closed)
nei
bevei
ei (open)
sei
lei
oi (closed)
voi
noi
oi (open)
poi
stoico
au
causa
aula
eu (closed)
feudale
leucoma
eu (open)
feudo
euro
Triphthongs
Italian also contains some triphthongs, which consist of three distinct vowel sounds all compressed into the space of a single syllable. A triphthong always contains one strong vowel and two weak vowels, generally with the strong vowel in the middle. Here is a non-exhaustive list of some Italian triphthongs with examples.
triphthong
example
iei (open)
miei
uoi (open)
suoi
uai
guai
iau
miaula
iai
cucchiai
Multi-syllabic vowels
Note that an important characteristic of a diphthong or a triphthong is that it is pronounced in the space of a single syllable. Don’t confuse this with the very common situation where two or more vowels are pronounced as multiple syllables. The following table shows some examples of this situation. Each example has a multi-vowel sequence in bold that is broken down into its constituent parts (mon = monophthong, dip = diphthong, trip = triphthong).
word
syllables
vowel sounds in sequence
paese
pa-e-se
mon “a” + mon “e”
museo
mu-se-o
mon “e” + mon “o”
biologo
bi-o-lo-go
mon “i” + mon “o”
puntuale
pun-tu-a-le
mon “u” + mon “a”
spia
spi-a
mon “i” + mon “a”
suo
su-o
mon “u” + mon “o”
diabete
di-a-be-te
mon “i” + mon “a”
statua
sta-tu-a
mon “u” + mon “a”
moina
mo-i-na
mon “o” + mon “i”
baule
ba-u-le
mon “a” + mon “u”
bui
bu-i
mon “u” + mon “i”
chiunque
chi-un-que
mon “i” + mon “u”
maiale
ma-ia-le
mon “a” + dip “ia”
aiuto
a-iu-to
mon “a” + dip “iu”
buio
bu-io
mon “u” + dip “io”
cuoio
cuo-io
dip “uo” + dip “io”
cucchiaio
cuc-chia-io
dip “ia” + dip “io”
cuoiai
cuo-iai
dip “uo” + trip “iai”
maoismo
ma-o-i-smo
mon “a” + mon “o” + mon “i”
cuoiaio
cuo-ia-io
dip “uo” + dip “ia” + dip “io”
Note that you can’t always tell from the spelling whether a particular vowel combination is pronounced as a dipthong or as two separate vowels. The following table demonstrates this using some of the previous examples.
diphthong
separate vowels
piove
biologo
quale
puntuale
noi
moina
aula
baule
guida
bui
fiume
chiunque
Common mistakes
One of the most common mistakes made by English speakers learning Italian is to mispronounce a single written vowel as a diphthong, especially at the end of a word. You should take special care to avoid this mistake. See if you can hear the difference between the correct and incorrect pronunciations of the following Italian words; the mispronounced vowels are in bold.
incorrect
correct
nome
nome
vino
vino
casa
casa
mela
mela
cosa
cosa
A closely related mistake is to mispronounce a diphthong as a triphthong.
incorrect
correct
loquela
loquela
niego
niego
viola
viola
Exercise
The following exercise contains all the examples of Italian diphthongs and triphthongs from this lesson. You should focus on getting all the vowel sounds correct and not be too concerned about the consonant sounds, which will be covered in later lessons.
