Sandhi phenomena in Spanish

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

mes raquettes [me ʁaˈkεt] ‘my rackets’, but:
mes amis [mez aˈmi] ‘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 a short 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’ can naturally 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 a single continuous unit. In a phonetic transcription vertical bars (or pipes), can be used to indicate the boundaries between intonational phrases:

[kwan̪doʎeˈɣaɾonlozβomˈbeɾos | noaˈβiaˈnað̞akeaˈθeɾ]
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 main sandhi processes affecting the Spanish consonants are shown as rules in Table 1 below, where the symbol ‘→’ should be interpreted as meaning ‘is modified to’.

Table 1 The sandhi rules of Spanish
	Sound	Rule	Example
Word-initial	[b, g]	→ [β, ɣ] except after nasal	[laˈβota] la bota ‘the boot’ [laˈɣera] la guerra ‘the war’
	[d]	→ [ð̞] except after nasal or lateral	[ˈojˈð̞ia] hoy día ‘these days’
	[ɟʝ]	→ [ʝ] except after nasal or lateral	[laˈʝema] la yema ‘the yolk’
Word-final	[θ, s]	→ [ð, z] before voiced consonant	[ˈluðˈβeɾð̞e] luz verde ‘green light’ [mizˈɣwan̪tes] mis guantes ‘my gloves’
	[s]	→ [ʒ] before voiced palatal (the latter is elided)	[laˈʒemas] las yemas ‘the yolks’
	[s]	→ [ɹ] or elided before [r]	[loɹˈreʝes] or [loˈreʝes] los reyes ‘the kings’
	[n]	→ any of [m, ɱ, n̪, n, ɲ, ŋ] depending on following consonant	[umˈbaso] un vaso ‘a glass’ [uɲˈɟʝate] un yate ‘a yacht’ [uŋˈkotʃe] un coche ‘a car’ etc.
	[l]	→ [ʎ] before voiced palatal	[eʎˈɟʝeso] el yeso ‘the plaster’

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 [unaβeˈβið̞ajnˈsulsa] 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:

[ˈpok^oefiˈkaθ] 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:

[l^aˈeβɾa] la hebra ‘the thread’

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

[s^eakaˈβo] 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:

[l^eoˈβliɣa] le obliga ‘he/she forces him/her’