A system for detecting parcel engagement and classifying parcels includes: a robot configured to engage and transfer parcels; one or more microphones configured to obtain sound recordings (audio data) and positioned to obtain audio data corresponding to the robot engaging a parcel for transfer; and a control subsystem. The control subsystem includes a controller which receives and processes the audio data obtained by the one or more microphones to detect engagement of the robot with the parcel and to classify a characteristic of the parcel, such as parcel type. The robot can be a vacuum-based end effector, with the one or more microphones a component thereof. A method for classifying parcels is also disclosed.