Sandhi phenomena in Spanish

1. Introduction
The term sandhi
(from Sanskrit saṃdhí ‘joining’) is used in linguistics to refer to the processes undergone by the form of a word or morphological formative under the influence of an adjacent word or morphological formative. For example, the plural form mes of the French possessive determiner usually changes its pronunciation from [me] to [mez] before a word that begins with a vowel:

mes raquettes [me Rakεt] ‘my rackets’, but:
mes amis [mez ami] ‘my friends’

This page deals with the sandhi processes that affect Spanish words when they are used in connected speech.


2. The intonational phrase
The primary unit of connected speech (in Spanish at least) is not the individual word but the intonational phrase. The latter can be defined as a sequence of speech that is uttered with a single intonational contour, usually corresponding to a syntactic unit, such as a phrase or clause. For example, the sentence Cuando llegaron los bomberos no había nada que hacer ‘When the firefighters arrived there was nothing that could be done’ would typically be uttered as two intonational phrases, viz. Cuando llegaron los bomberos and no había nada que hacer.

Within the intonational phrase individual word boundaries are erased. In other words, each of the sequences Cuando llegaron los bomberos and no había nada que hacer would be pronounced as if it were a single word. In a phonetic transcription vertical bars (or pipes), can be used to indicate the boundaries between intonational phrases:

[ˈkwandoʎeˈɣaɾonlozβomˈbeɾos | noaˈβiaˈnaðakeaˈθeɾ]
Cuando llegaron los bomberos – no había nada que hacer.


3. Sandhi processes
Within the intonational phrase, the initial and final sounds of individual words often undergo certain modifications. In the example above, for instance, the final /s/ of los is realized as [z] rather than [s] due to the voiced consonant that begins the next word bomberos. Such modifications are examples of sandhi processes.

3.1. Consonants
In terms of consonants, the sandhi processes that occur in Spanish parallel closely, though not completely, the allophonic rules that apply within words. The rules governing these processes are shown in the table below, where the symbol ‘→’ should be interpreted as meaning ‘is modified to’.

The sandhi rules of Spanish






[b, g]

→ [β, ɣ] except after nasal

[laˈɣera] la guerra ‘the war’


→ [ð] except after nasal or lateral

[ˈojˈðia] hoy día ‘these days’


→ [ʝ] except after nasal or lateral

[laˈʝema] la yema ‘the yolk’


[θ, s]

→ [ð, z] before voiced consonant

[mizˈɣwantes] mis guantes ‘my gloves’

[s] → [ʒ] before voiced palatal (the latter is elided) [laˈʒemas] las yemas ‘the yolks’


→ [ɹ] or elided before [r]

[loɹˈreʝes] or [loˈreʝes] los reyes ‘the kings’

[m, n]

→ any of [m, ɱ, n, ɲ, ŋ] depending on following consonant

[umˈbaso] un vaso ‘a glass’
[uŋˈkotʃe] un coche ‘a car’ etc.


→ [ʎ] before palatal consonant

[eʎˈtʃiko] el chico ‘the boy’


3.2. Vowels
In terms of vowels, relaxed speech tends towards synalepha or vowel reduction at word boundaries. The most common process involves modifying word-initial [i] or [u] to the corresponding semivowel (i.e. [j] or [w]) after a word ending in a vowel, as in [unaβeˈβiðajnˈsulsa] una bebida insulsa ‘an insipid drink’ and [paɾawˈniɾ] para unir ‘in order to connect’. This process is blocked in careful speech when the [i] or [u] belongs to a stress-bearing syllable, as in [loˈiθo] lo hizo ‘he did it’. In rapid speech, even a stressed [i] or [u] may be modified to [j] or [w], but in that case stress shift must occur: [lo] + [ˈiθo] → [ˈlojθo].

A more variable process involves pronouncing two full vowels straddling a word boundary as a single syllable by reducing or eliding one of them, as in the two examples below:

[ˈpokoefiˈkaθ] poco eficaz ‘not very effective’
[aθjaˈtɾas] hacia atrás ‘backwards’

When the two contiguous vowels are unidentical, a hierarchy of rules usually governs which of the two is reduced. In the first place, a stressed vowel normally prevails over an unstressed one:

[laˈeβɾa] la hebra ‘the thread’

If neither are stressed, the lower of the two normally prevails over the other

[seakaˈβo] se acabó ‘it finished’

Finally, if neither are stressed and the two have height parity, it is usually the vowel that occupies word-initial position that prevails:

[leoˈβliɣa] le obliga ‘he/she forces him/her’