Playback system, control device, control method, and program

A control method for controlling frequency characteristics of a playback device that is connected to or integrated with a loudspeaker installed in a room using a control device provided outside the playback device, the control device including:

• a first communication circuit that communicates with the playback device;
• a microphone that acquires a sound signal generated through the loudspeaker;
• and
• a first control circuit,
• the control method comprising:
• acquiring background noise in the room through the microphone and calculating a signal level of the background noise at a plurality of predetermined frequencies;
• transmitting, to the playback device via the first communication circuit, a first control signal directing playback of a first test signal having a predetermined sound volume through the loudspeaker;
• acquiring the first test signal through the microphone and calculating a signal level of the acquired first test signal;
• estimating a signal level of a second test signal having a predetermined sound volume and predetermined frequency characteristics at the plurality of predetermined frequencies using the signal level of the first test signal as a reference;
• increasing a set value of the sound volume of the second test signal when a signal level obtained by subtracting a predetermined value from the estimated signal level of the second test signal is less than or equal to the signal level of the background noise in at least one of the plurality of predetermined frequencies;
• transmitting, to the playback device via the first communication circuit, a second control signal directing playback of the second test signal having a sound volume corresponding to the set value through the loudspeaker;
• acquiring the second test signal through the microphone, calculating a frequency response of the room based on the acquired second test signal, and calculating a correction coefficient of frequency characteristics to be set to the playback device based on the calculated frequency response of the room;
• and
• transmitting, to the playback device via the first communication circuit, a third control signal including the correction coefficient of the frequency characteristics to be set to the playback device.

A non-transitory computer-readable recording medium storing a program to be executed by a control device that controls frequency characteristics of a playback device connected to or integrated with a loudspeaker installed in a room for performing control processing, the control device including:

• a first communication circuit that communicates with the playback device;
• a microphone that acquires a sound signal generated through the loudspeaker;
• and
• a first control circuit that executes the program,
• the control processing comprising:
• acquiring background noise in the room through the microphone and calculating a signal level of the background noise at a plurality of predetermined frequencies;
• transmitting, to the playback device via the first communication circuit, a first control signal directing playback of a first test signal having a predetermined sound volume through the loudspeaker;
• acquiring the first test signal through the microphone and calculating a signal level of the acquired first test signal;
• estimating a signal level of a second test signal having a predetermined sound volume and predetermined frequency characteristics at the plurality of predetermined frequencies using the signal level of the first test signal as a reference;
• increasing a set value of the sound volume of the second test signal when a signal level obtained by subtracting a predetermined value from the estimated signal level of the second test signal is less than or equal to the signal level of the background noise in at least one of the plurality of predetermined frequencies;
• transmitting, to the playback device via the first communication circuit, a second control signal directing playback of the second test signal having a sound volume corresponding to the set value through the loudspeaker;
• acquiring the second test signal through the microphone, calculating a frequency response of the room based on the acquired second test signal, and calculating a correction coefficient of frequency characteristics to be set to the playback device based on the calculated frequency response of the room;
• and
• transmitting, to the playback device via the first communication circuit, a third control signal including the correction coefficient of the frequency characteristics to be set to the playback device.