An audio signal processing method including obtaining a first audio signal by generating a pattern in association with the first audio signal to be output, outputting the first audio signal, receiving, through an external voice input device while the external voice input device is communicatively connected to the audio signal processing device, a second audio signal including the output first audio signal, detecting the pattern from the second audio signal, and synchronizing the second audio signal with the first audio signal based on the pattern detected from the second audio signal and the pattern included in the first audio signal.