An apparatus comprising: at least one speaker module disposed within the apparatus so as to generate sound emanating from the apparatus, wherein the at least one speaker module is at least one loudspeaker within the apparatus and acoustically coupled to an acoustic cavity and an aperture of the apparatus, to generate sound emanating from the apparatus; at least one microphone disposed within the apparatus such that there is a physical distance between the at least one speaker module and the at least one microphone, wherein the at least one microphone is positioned to detect acoustic reflections of sounds originating from the at least one speaker module and reflected back to the apparatus from objects around the apparatus; at least one filter configured to filter an electrical input signal and provide a filtered electrical input signal to the at least one speaker module of the apparatus for handsfree operations, said at least one speaker module configured to convert the filtered electrical input signal into an acoustic signal; and a detector configured to receive as an input the filtered electrical input signal and an electrical output signal provided by the at least one microphone of the apparatus; wherein the detector is configured to determine at least one difference between the electrical output signal provided by the at least one microphone and the filtered electrical input signal provided to said at least one speaker module, wherein the at least one difference comprises one or more of: a difference in frequency response between the electrical output signal and the filtered electrical input signal; and a difference between the filtered electrical input signal and the electrical output signal in the time domain provided by a cross-correlation process; and the detector is further configured to provide, in response to the at least one difference, a control signal to the at least one filter to adjust the filtered electrical input signal. at least one speaker module disposed within the apparatus so as to generate sound emanating from the apparatus, wherein the at least one speaker module is at least one loudspeaker within the apparatus and acoustically coupled to an acoustic cavity and an aperture of the apparatus, to generate sound emanating from the apparatus; at least one microphone disposed within the apparatus such that there is a physical distance between the at least one speaker module and the at least one microphone, wherein the at least one microphone is positioned to detect acoustic reflections of sounds originating from the at least one speaker module and reflected back to the apparatus from objects around the apparatus; at least one filter configured to filter an electrical input signal and provide a filtered electrical input signal to the at least one speaker module of the apparatus for handsfree operations, said at least one speaker module configured to convert the filtered electrical input signal into an acoustic signal; and a detector configured to receive as an input the filtered electrical input signal and an electrical output signal provided by the at least one microphone of the apparatus; wherein the detector is configured to determine at least one difference between the electrical output signal provided by the at least one microphone and the filtered electrical input signal provided to said at least one speaker module, wherein the at least one difference comprises one or more of: a difference in frequency response between the electrical output signal and the filtered electrical input signal; and a difference between the filtered electrical input signal and the electrical output signal in the time domain provided by a cross-correlation process; and the detector is further configured to provide, in response to the at least one difference, a control signal to the at least one filter to adjust the filtered electrical input signal. a difference in frequency response between the electrical output signal and the filtered electrical input signal; and a difference between the filtered electrical input signal and the electrical output signal in the time domain provided by a cross-correlation process; and the detector is further configured to provide, in response to the at least one difference, a control signal to the at least one filter to adjust the filtered electrical input signal.