As part of a system, a device is provided as part of a system, the device being for capturing vibrations produced by an object such as a musical instrument. The device has a first sensor placed in contact with a surface of the drum, such as a rim of the drum, and a second sensor placed at a fixed location relative to the drum, but not touching the drum. A method may be provided for interpreting the output of the sensors within the system, the method comprising identifying the onset of an audio event in audio data, selecting a window in the data for analysis, applying transforms to generate a representation of the audio event, and comparing that representation to expected representations in a model.