28 Chapter 2
states. Why are vowels more likely to be produced correctly and consonants misarticulated by
children? Four acoustic, physiological, and perceptual factors can account for this difference.
First, vowels are less likely to be misarticulated because all vowels are voiced. Voicing gives
phonemes greater acoustic energy and sends the listener more perceptual features about their pro-
duction. Second, vowels are less complicated to articulate than consonants. Although fine tongue
and lip- rounding movements are necessary to produce vowels, consonants typically require more
articulatory excursions, making them more vulnerable to misarticulation. Third, vowels are the
core of the syllable, so their acoustic, physiological, and perceptual features are more con spic u ous
and salient. Fi nally, as a group, vowels occur more frequently than consonants, giving the person
more opportunities to learn them. Figure 2-5 shows the ages at which vowels and diphthongs are
mastered.
Accent and Dialect
Accents and dialects are more varied in the eastern United States because that is where many
immigrants first settled (Alvarez & Kolker, 1987). These terms are often used interchangeably,
but technically they differ. An accent indicates the articulation traits of the speaker’s first learned
language carried over to a second acquired language. A dialect is a specific pronunciation and
vocabulary used in a par tic u lar geo graph i cal area and socioeconomic stratum and can include an
accent. There are no substandard accents and dialects; all rule- governed cultural variations in the
production and use of speech and language are normal.
Accent and dialect are nonstandard, not substandard, speech and language. They are examples
of complex linguistic variations and social adaptation. Wolfram (1986) comments on the com-
plexities of these linguistic variations:
Figure 2-4. Developmental Articulation and Phonology Profile consonants. (Reprinted with permission
from Academic Communication Associates.)