Audio system for a collection box

Systems, devices, and techniques for producing audio for, or adding audio capability to, a collection box for delivery items that includes a user-operated door for putting items into the collection box. The system can include a processing subsystem, an audio transducer, a trigger device that is connected to, or that is part of, the door of the collection device, and a sensor. The sensor detects the trigger device when the trigger device is in close proximity (e.g., in contact), and the sensor is positioned such that it is in close proximity with the trigger device when the door is closed. In response to the trigger device moving out of close proximity, the sensor generates a signal to the processing system. In response, the processing system generates an audio signal that is converted to sound by the audio transducer, which can be heard outside of the collection box.