Abstract: A method and a control circuit for performing synchronization on playback of multiple electronic devices are provided, where the multiple electronic devices include a master device and a slave device. The method includes: utilizing the master device to receive audio data from a far-end device to be master audio data, and transmitting the master audio data to the slave device to be slave audio data, where the slave device generates ultrasound data according to the slave audio data, to make the slave device play the slave audio data and the ultrasound data; utilizing a calibration circuit to estimate a delay value between the ultrasound data received by a microphone of the master device and the master audio data; and utilizing a delay circuit to control a delay of the master audio data according to the delay value, to generate master output audio data for being played by the master device.

Abstract: An audio playback method includes the following steps: receiving an ultrasound signal via a microphone; processing the ultrasound signal to obtain a characteristic value of the ultrasound signal; obtaining time lag information based on the characteristic value; and controlling audio delay according to the time lag information.

Abstract: An audio playback method includes the following steps: receiving an ultrasound signal via a microphone; processing the ultrasound signal to obtain a characteristic value of the ultrasound signal; obtaining time lag information based on the characteristic value; and controlling audio delay according to the time lag information.

Abstract: A method for calculating excursion of a diaphragm of a speaker, which includes: calculating a DC resistance based on a feedback signal of the speaker; calculating an impedance based on the feedback signal and the DC resistance; calculating a transfer function between a signal and a velocity of the diaphragm of the speaker based on the DC resistance, the impedance, and a force factor; and calculating the excursion of the diaphragm of the speaker based on an input signal and the transfer function.

Abstract: A method for calculating excursion of a diaphragm of a loudspeaker is provided. The loudspeaker includes a diaphragm and is driven by a voltage signal. The method includes: a) low-pass filtering the voltage signal and a current signal inputted to the loudspeaker to generate a low-pass filtered voltage signal and a low-pass filtered current signal, respectively; b) calculating a direct-current (DC) resistance of the loudspeaker according to the low-pass filtered voltage signal and the low-pass filtered current signal; c) calculating a vibration velocity of the diaphragm according to the voltage signal, the current signal and the DC resistance; and d) calculating the excursion of the diaphragm according to the vibration velocity. Step (a) to step (d) involve real-number calculations.