delete the first element in such clusters, for example 'psychology'. When attempting to pronounce such words for the first time without deleting the first consonant, Spanish speakers insert a short, often devoiced, schwa-like svarabhakti vowel between the two consonants. Spanish syllable structure is phrasal, resulting in syllables consisting of phonemes from neighboring words in combination, sometimes even resulting in elision. The phenomenon is known in Spanish as enlace. For a brief discussion contrasting Spanish and English syllable structure, see . Acquisition as a first language Phonology Phonological development varies greatly by individual, both those developing regularly and those with delays. However, a general pattern of acquisition of phonemes can be inferred by the level of complexity of their features, i.e. by sound classes. A hierarchy may be constructed, and if a child is capable of producing a discrimination on one level, they will also be capable of making the discriminations of all prior levels. The first level consists of stops (without a voicing distinction), nasals, , and optionally, a non-lateral approximant. This includes a labial/coronal place difference (for example, vs and vs ). The second level includes voicing distinction for oral stops and a coronal/dorsal place difference. This allows for distinction between , , and , along with their voiced counterparts, as well as distinction between and the approximant . The third level includes fricatives and/or affricates. The fourth level introduces liquids other than , and . It also introduces . The fifth level introduces the trill . This hierarchy is based on production only, and is a representation of a child's capacity to produce a sound, whether that sound is the correct target in adult speech or not. Thus, it may contain some sounds that are not included in the adult phonology, but produced as a result of error. Spanish-speaking children will accurately produce most segments at a relatively early age. By around three-and-a-half years, they will no longer productively use phonological processes the majority of the time. Some common error patterns (found 10% or more of the time) are cluster reduction, liquid simplification, and stopping. Less common patterns (evidenced less than 10% of the time) include palatal fronting, assimilation, and final consonant deletion. Typical phonological analyses of Spanish consider the consonants , , and the underlying phonemes and their corresponding approximants , , and allophonic and derivable by phonological rules. However, approximants may be the more basic form