Methods and devices for measuring vibration of an implanted driven vibrating elongate body coupled to a bone of the middle ear, for example using an accelerometer coupled to the vibrating body. The measured vibration can be taken during implantation and long again after implantation to check for possible decoupling, disease, or additionally impeded vibratory driving of the middle ear bone. An accelerometer signal can be converted to a displacement value and used to check for an under impeded or over impeded vibratory body. An implanted device can be used to periodically check the vibration of the vibratory body. Methods and devices can be used in conjunction with implanted devices which receive vibratory signals from a middle ear bone and use the signals to drive a disarticulated middle ear bone closer to the ear drum.