Based on an auditory neuron model developed from the piezoelectric neural circuit, two different stimuli (F1, F2) are respectively used and then combined (F1+F2) synchronously to trigger different firing modes (S1, S2, S3). The Hamilton energy for each firing mode is calculated to discern the effect from the external stimulus, and the final firing mode is mainly controlled by one of the stimuli which can induce a higher Hamilton energy in the neuron. The external forcing inducing spiking has priority than the external stimulus inducing bursting to be responded by the neuron. The involvement of periodic firing modes is helpful to induce nonlinear resonance and thus new periodic firing modes can be generated even it presents lower Hamilton energy. The changes in the profile of periodic attractors confirm that external stimuli for inducing spiking and bursting can be perceived sensitively. In case of chaotic firing modes resulting from chaotic driving, the contribution from spiking, bursting and even periodic forcing can be detected because the profile of chaotic attractors is also changed greatly. A correlation function is defined to discern the effect of external stimuli on the selection of firing modes in the neuron driven by multi-channel stimuli. The results confirmed that the neuron is more sensitive to the external stimulus which can release higher Hamilton energy and/or induce high regularity in the neural activities. This study discovers the potential response mechanism in the auditory neuron under external stimuli.