JANUS [17] was designed for the translation of spontaneous human-to-human speech. Before the 1994 CSR evaluation, JANUS was run with vocabularies of up to 2500 words. JANUS was also tested on the Conference Registration and the Resource Management tasks. The best error rate on the '89 Resource Management evaluation set was 5.9%. At the June 1994 Verbmobil speech component evaluation [1], JANUS scored best among eight participants on the German appointment scheduling task, a task of spontaneous human to human dialogs. In this paper we give a detailed description of the recognition engine of JANUS, focusing on the acoustic modeling and our first run with the WSJ task. 1. ACOUSTIC MODELING IN JANUS 1.1 PREPROCESSING For the 1994 CSR evaluation we computed 16 mel scale spectral coefficients from an FFT with a window size of 256 sample points and a window shift (frame rate) of 10 ms. 16 mel spectral coefficients, 16 delta coefficients, and 16 delta-delta coefficients were used to build a 4...