canadian linguist j.k. chambers, conducted a study applying the apparent-time hypothesis. the study, carried out in central canada, examined the sociolinguistic variable (wh), where the unvoiced labiovelar glide /hw/ loses phonemic status and merges with the corresponding voiced glide /w/. in this study, the oldest subjects seem to indicate a stable period for this variable, both the 70- to 79-year-olds and those over 80 used the voiced variant where the unvoiced was "expected" 38.3 and 37.7% of the time, respectively. each subsequent younger age cohort (10 years) shows a greater percentage of /w/ usage, with those 20–29 using /w/ 87.6% of the time and the teenagers using it 90.6% of the time. notice that the deltas between the oldest two groups and between the youngest two groups are relatively small, 0.6% and 3.0%. between these two extremes the rate of change between the groups is quite high, approximately 10% per age cohort. this pattern can be described as an initial stable period, followed by a period of rapid change, and a tailing off as the change nears completion. this s-curve pattern has been identified as characteristic for many types of linguistic changes.