1. A hearing aid, comprising: a microphone to receive sounds and produce analog signals representative of the received sounds; a receiver for playing sound; an analog-to-digital converter to convert the analog signals from the microphone into a digital representation; a sound processor to process the digital representation and create a digital output for the receiver; and an acoustic feedback estimator to generate an acoustic feedback estimate representing a time-varying acoustic feedback from the receiver to the microphone, the acoustic feedback estimate based on the digital output and an error signal based on a difference between the digital representation and the acoustic feedback estimate, the acoustic feedback estimator including an adaptive bulk delay to compensate for changes in the acoustic feedback signal, the adaptive bulk delay comprising: a memory to receive the digital output, the memory including a plurality of memory locations for storing a plurality of digital samples and a pointer for pointing to certain digital samples; a coefficient update module that receives the error signal and the digital samples and generates new filter coefficients; a coefficient memory that stores the new filter coefficients and includes a coefficient pointer for pointing to certain new filter coefficients; a filter that receives a delayed version of the digital output from the memory and the new filter coefficients; and a delay rules module providing outputs for controlling the pointer of the memory and the coefficient pointer of the coefficient memory based on the new filter coefficients to adjust the adaptive bulk delay.