Automatic speech recognition systems transform speech audio data into text data, i.e., word sequences, as the recognition results. These word sequences are generally defined by the language model of the speech recognition system. Therefore, the capability of the speech recognition system to translate audio data obtained by typically pronouncing word sequences that are accepted by the language model into word sequences that are equivalent to the original ones can be regarded as a basic capability of the speech recognition systems. This work describes a testing method that checks whether speech recognition systems have this basic recognition capability. The method can verify the basic capability by performing the testing separately from recognition robustness testing. It can also be fully automated. We constructed a test automation system and evaluated though several experiments whether it could detect defects in speech recognition systems. The results demonstrate that the test automation system can effectively detect basic defects at an early phase of speech recognition development or refinement.