In certain varieties of Southern States English and African-American English, there is a phonological phenomenon in which a voiced alveolar fricative 
is pronounced as a voiced alveolar stop 
before a nasal consonant. For example, the sound 
in contracted words such as isn't (SAE 
) and wasn't (SAE 
) is pronounced as the sound . Thus, the words like isn't and wasn't are pronounced 
and 
. Troike (1986) names this phenomenon McDavid's Law, in reference to McDavid (1942), in which McDavid first attempted to state this phenomenon as a rule.
There is evidence that the -> distinction can be found in other lexical items in some varieties of Southern States English. For example, a word like business (SAE 
) is pronounced as 
in some varieties. Other attested examples include cousin 
, pleasant 
, and present 
(McMillan 1946 (transcriptions by eds.)). Taylor (1997) theorizes that this phenomenon may be part of a general rule in some varieties. This general rule would include application to the voiced affricate 
and the voiced fricative 
as well as . He cites as evidence pronunciations of regional, emergency, and register with 
. For example, he provides the transcription of register in some varieties as 
Phonologically, this sound variation can be accounted for by the assimilation of the feature [-continuant] from the nasal consonant to the , changing the sound from a fricative to a stop.
Different sources of evidence seem to indicate that this phenomenon has its origins in southwestern England (Feagin 1979, Troike 1986, Reynolds 1994). There are references to a rule in dialects of this area in which became in negative contracted forms of be; that is, in the forms isn't and wasn't. Reynolds (1994) proposes that the -> rule began with the word wasn't, which became through analogy with other past tense negative auxiliary contractions. The following table, from Reynolds (1994), illustrates the analogy:
| could | couldn't |
| would | wouldn't |
| should | shouldn't |
| might | mightn't |
| had | hadn't |
| did | didn't |
| was | X = wadn't |
As the table shows, all other negative contractions of past tense auxiliaries ended in either 
or 
. Therefore, by analogy, wasn't came to end in . A second analogical change resulted in the pronunciation of isn't as . Since isn't is the present tense form of wasn't, isn't took on the pronunciation to match the pronunciation of the past tense form.
Once this phenomenon had migrated to the American South, the rule began to generalize, affecting some lexical items as business and cousin. However, this change has been arrested, with only a few lexical items participating in the rule.
The following samples are from a white male speaker over 60 from Eastern Texas. Both samples include the word business.
© 2001 The Language Samples Project