Abstract: A monitoring device is used to monitor the performance of a burnishing apparatus that uses a burnishing tape. The monitoring device monitors the contact between the burnishing tape and the disk. The monitoring device may include an acoustic emission sensor, e.g., a piezo-electric transducer, that is mounted on the elements that press the burnishing tape into contact with the disk. Elastic waves that are produced by the contact between the burnishing tape and the disk propagate through the pressure applying element, received by the sensor and are converted into electric signals. The electric signals from the sensor are converted into amplitude signals in the time domain and/or signals in the frequency domain. Alternatively, the monitoring device may measure the elastic waves propagating through the disk, the tension on the burnishing tape, and/or the frictional force between the burnishing tape and the disk.