Exclusions, Deletions, Total Measurements.

Within the segment of speech chosen, ranging from a few minutes to nearly half an hour, an attempt was made to examine every single occurring vowel. A small percentage of the vowels are devoiced or otherwise deleted in speech, while another, usually small subset was excluded due to background noises or overlapping speech. The overall numbers of tokens in these various categories are shown in Table . For each dialect and speaker, it lists the total number of vowels examined, the number of vowels which were found to correspond to no acoustic vowel (that is, those which were phonetically deleted, devoiced, etc.), the number of vowels which were excluded due to overlapping speech, or background noises, and the total number of vowels measured.

Table: Numbers of tokens, deletions, exclusions, measurements.

Dialect	Speaker	Total	= n(VØ)	+ n(excl.)	+ n(meas.).	%(VØ)
JC	Juba B.	2891	82	129	2680	3.0%
JC	Roasta M.	1872	75	124	1673	4.3%
CWE	Rita S.	4821	211	140	4470	4.5%
CWE	Jim C.	2856	121	406	2329	4.9%
CWE	Judy H.	1775	105	55	1615	6.1%
AE	James H.	1818	137	43	1638	7.7%
LACE	Vince M.	2190	104	196	1890	5.2%

%(VØ) = 100*n(VØ)/(n(VØ)+n(meas.)).

The percentage of phonological vowels which were found to be associated with no measurable acoustic vowel segment is calculated as the number of phonetically deleted segments out of the total number of measurable segments.

The deleted/devoiced tokens might be used as data for another study, examining the conditioning of vowel deletion and/or devoicing. My impression, as might have been expected, was that vowels deleted most often between voiceless obstruents. A more detailed characterization of these exclusions will have to await further analysis beyond the scope of this book.