A new method of processing borehole acoustic array data is described. The method detects arrivals by computing the scalar semblance for a large number of possible arrival times and slownesses. Maxima of semblance are interpreted as arrivals. Their associated slownesses are plotted on a graph whose axes are slowness and depth. The processing makes few prior assumptions about data and the algorithm is uncomplicated. Results of the processing applied to data from a 12-receiver device are presented for both open and cased holes.--Modified journal abstract.