Classical room acoustics are based on the interpretation of different sound attributes such as reverberation time, clarity and spatial decay. Based on echograms calculated from a microphone array, the dispersion of early reflections is measured and the reflections are identified. In small auditoriums, the method delivers some comprehensive information of the acoustic paths between the source and the microphone array qualifying global and local characteristics of the room boundaries. Results validate the process and highlight its contributions, but also the difficulties of implementation.