Systems and methods for selecting audio samples in response to musical stimuli are provided. In some embodiments, an audio sample can be selected based on the excitation state of an instrument. A musical stimulus can be received, and a current excitation level associated with previously received musical stimuli calculated. An audio sample can be selected for playback using the current excitation level. In some embodiments, audio samples having different velocity levels can be selected in response to repeated musical stimuli. A first instance of a musical stimulus having a first velocity level can be received, and a first audio sample corresponding to the first velocity level played back. A second instance of the musical stimulus having the first velocity level can be received, and a second audio sample corresponding to a second velocity level can be selected for playback. The first and second audio samples can have different audio characteristics.