A portable device comprising: a wireless sink; a signal processor; a wireless source; at least one microphone configured to receive audio from outside the portable device; and at least one of at least one speaker and a line out, wherein the device is configured to receive a wireless signal using the wireless sink, process the signal using the signal processor, and transmit a wireless signal using the wireless source depending on what audio is received from the at least one microphone, and wherein the portable device is configured to at least one of emit sound using the at least one speaker and provide signals to the line out depending on what audio is received from the at least one microphone, wherein the portable device further comprises: a digital audio buffer configured to receive signals from the signal processor; wherein the portable device is characterised in that it comprises a synchronizing circuitry configured to receive signals from both the at least one microphone and the digital audio buffer, wherein the synchronizing circuitry is configured to employ cross correlation to effect calibration of the device; and an amplifier, wherein the digital audio buffer is configured to receive signals from the synchronizing circuitry and provide signals to the amplifier; wherein the portable device is configured to: add a delay if, after comparing peaks of a cross correlation of signals received by the synchronizing circuitry, it is determined that a highest peak is sufficiently greater than a next highest peak, and also sufficiently greater than a mean of the cross correlation of the signals received by the synchronizing circuitry; and not add a delay and instead repeat a calculation if it is determined that the highest peak of the cross correlation is not sufficiently greater than the next highest peak, or not sufficiently greater than the mean, wherein the amplifier is configured to drive said at least one speaker to produce sound, and wherein the portable device is configured to improve an accuracy of calibration by filtering signals received by the synchronizing circuitry according to those frequencies which can be detected by the synchronizing circuitry using the at least one microphone. a digital audio buffer configured to receive signals from the signal processor; wherein the portable device is characterised in that it comprises a synchronizing circuitry configured to receive signals from both the at least one microphone and the digital audio buffer, wherein the synchronizing circuitry is configured to employ cross correlation to effect calibration of the device; and an amplifier, wherein the digital audio buffer is configured to receive signals from the synchronizing circuitry and provide signals to the amplifier; wherein the portable device is configured to: add a delay if, after comparing peaks of a cross correlation of signals received by the synchronizing circuitry, it is determined that a highest peak is sufficiently greater than a next highest peak, and also sufficiently greater than a mean of the cross correlation of the signals received by the synchronizing circuitry; and not add a delay and instead repeat a calculation if it is determined that the highest peak of the cross correlation is not sufficiently greater than the next highest peak, or not sufficiently greater than the mean, wherein the amplifier is configured to drive said at least one speaker to produce sound, and wherein the portable device is configured to improve an accuracy of calibration by filtering signals received by the synchronizing circuitry according to those frequencies which can be detected by the synchronizing circuitry using the at least one microphone. add a delay if, after comparing peaks of a cross correlation of signals received by the synchronizing circuitry, it is determined that a highest peak is sufficiently greater than a next highest peak, and also sufficiently greater than a mean of the cross correlation of the signals received by the synchronizing circuitry; and not add a delay and instead repeat a calculation if it is determined that the highest peak of the cross correlation is not sufficiently greater than the next highest peak, or not sufficiently greater than the mean, wherein the amplifier is configured to drive said at least one speaker to produce sound, and wherein the portable device is configured to improve an accuracy of calibration by filtering signals received by the synchronizing circuitry according to those frequencies which can be detected by the synchronizing circuitry using the at least one microphone.