The paper tests the generalization of the curvilinear hypothesis and the tendency of females to lead linguistic change in vocalic mergers on the basis of two mergers currently in progress in Charleston, SC: the low-back merger and the pin-pen merger. It is based on minimal-pair tests and on the acoustic analysis of the speech of 90 speakers, aged 8-90, representing the entire socio-economic spectrum of the city. While the low-back merger is a change from below showing a female advantage and a curvilinear effect of social class, the pin-pen merger shows a decreasing monotonic relationship with social class and no female lead. The difference is argued to be due to the two mergers being at different levels of conscious awareness in the community.