Neutralization in Spanish
Spanish has three nasal phonemes, viz. /m/ ~ /n/ ~ /ɲ/. A perusal of the Spanish vocabulary reveals that there are no minimal contrasts involving these phonemes when the following sound is a consonant. It turns out, in fact, that the corresponding phonetic segments [m], [n] and [ɲ] are each restricted in terms of the type of consonant before which they can occur. Thus [m] can only occur before bilabials (as in [kampo] campo ‘field’ and [ambos] ambos ‘both’), [n] can only appear before alveolars/dentals (as in [sonrie] sonríe ‘smiles’) and [ɲ] can only appear before palatals (as in [baɲdʒo] banyo ‘banjo’).These restrictions could in principle be treated as cases of defective distribution, i.e. we could say simply that the phoneme /m/ cannot appear before non-bilabials, that /n/ cannot appear before non-alveolars/dentals and that /ɲ/ cannot appear before non-palatals. But by looking at matters in that way, we would miss an important generalization, because the gap in the distribution of each nasal is not at all arbitrary. Rather, some controlling factor seems to be at work, one which requires the place of articulation of a preconsonantal nasal to match the following consonant’s own place of articulation: bilabial with bilabial, alveolar with alveolar/dental and palatal with palatal. This is turn means that the place of articulation feature is not phonemically distinctive for preconsonantal nasals. But that is precisely the feature that formed the basis for distinguishing between /m/, /n/ and /ɲ/ in the first place. What the phonologist would say, then, is that in Spanish the /m/ ~ /n/ ~ /ɲ/ distinction is suspended or neutralized before a consonant. In this case we posit a so-called archiphoneme, which subsumes all of the nasal phonemes when the distinction or opposition between them is neutralized. The symbol for the nasal archiphoneme is /N/. For example, the words campo, cantar and ancho would be transcribed phonemically as /kaNpo/, /kaNtaɾ/ and /aNtʃo/ respectively. Their phonetic transcriptions would be [kampo], [kantaɾ] and [aɲtʃo].
This particular case of neutralization is also an instance of assimilation, the process whereby sounds become more alike. Thus another way of putting matters would be to say that, in Spanish, a nasal consonant that is immediately followed by another consonant assimilates to that consonant (in terms of its place of articulation).
We have so far only considered assimilation to bilabials, alveolars and palatals. But the process is induced also by labiodental and velar consonants, producing the labiodental and velar nasals [ɱ] and [ŋ] respectively (e.g. [eɱfeɾmo] enfermo ‘ill’, [beŋga] venga ‘come on’). Because [ɱ] and [ŋ] occur only immediately before a consonant, i.e. only in positions of neutralization, assigning them to one of the nasal phonemes /m/, /n/ or /ɲ/ would be quite arbitrary. Instead they must be assigned directly to the archiphoneme /N/.
Thus /N/ in Spanish has five allophones (i.e. five for which separate IPA symbols exist). These are [m], [ɱ], [n], [ɲ] and [ŋ]. Which of these actually occurs in a given context is determined entirely by the principle of assimilation.
Laterals also undergo assimilation in preconsonantal position, but only under the influence of palatals, as in [koʎtʃon] colchón ‘mattress’. Therefore, using /L/ to designate a lateral archiphoneme, we have the following distributional statement:
/L/ when immediately followed by a palatal is realized as [ʎ].Finally, the distinction between the vibrants /r/ and /ɾ/ is also neutralized in all positions except between vowels, meaning that we can posit a vibrant archiphoneme /R/. The distributional rule is as follows:
Elsewhere /L/ is realized as [l].
/R/ is realized as the trill [r] in word-initial position and after a nasal, a lateral or /s/.Some examples: [relox] reloj ‘watch’, [onra] honra ‘honour’, [alreðeðoɾ] alrededor ‘around’, [iɹrael] or [irael] Israel, [atɾako] atraco ‘robbery’, [kaɾne] carne ‘meat’.
Elsewhere /R/ is realized as the tap [ɾ].