Abstract: A portable computing device is used for acoustic testing of valve systems for valve leaks. Transducers are applied to appropriate locations in the valve system to obtain sound signals, which are fast Fourier transformed into valve signatures. Multiple signatures are displayed simultaneously and are compared automatically by the system to derive a recommended result and manually to make determinations of valve leaks by the differential signature method or the like. The signatures and the user's determinations are stored on a hard drive. Various panels are displayed to give the user step-by-step instructions for performing the test. The results can be reported to the client's office computers.