Method and apparatus for adjusting a cross-over frequency of a loudspeaker

1. A method for adjusting a cross-over frequency of a loudspeaker system, the loudspeaker system comprising at least a first loudspeaker for frequencies below the cross-over frequency and a second loudspeaker for frequencies above the cross-over frequency, wherein the method comprises:

matching a level of the first loudspeaker with the second loudspeaker using a first test signal;

obtaining a room response on the basis of the first test signal by:

sweeping a frequency range of the first test signal;

providing the first test signal to the first loudspeaker and the second loudspeaker to produce audible signals sweeping the frequency range;

receiving the audible signals; and

computing an estimate of summed total harmonic distortion on the basis of the received signals;

compensating the room response in the loudspeaker system;

measuring the compensated room response using a second test signal;

determining a maximum frequency for the first loudspeaker by examining a frequency response of the first loudspeaker and determining a roll-off point of the first loudspeaker;

determining a minimum frequency for the second loudspeaker by examining a frequency response of the second loudspeaker and determining a roll-off point of the second loudspeaker; and

searching a cross-over frequency between the minimum and maximum frequency that results in a minimum cumulative total harmonic distortion energy at one or more sound pressure levels by simulating a number of frequencies between the minimum and maximum frequency and measuring the cumulative total harmonic distortion energy at each of the frequencies.

2. The method according to claim 1 further comprising adjusting the frequency response of the loudspeaker system to compensate the room response.

3. The method according to claim 1 , wherein the matching level comprises:

generating the first test signal;

providing the first test signal to the loudspeaker system to form a first acoustic signal;

receiving the first acoustic signal by a microphone to form a first electric response signal;

using the first electric response signal to obtain level information of the loudspeaker system; and

wherein the method further comprises adjusting the level of at least one of the first loudspeaker and the second loudspeaker.

4. The method according to claim 1 , wherein the matching level comprises:

generating the first test signal;

providing the first test signal to the loudspeaker system to form a first acoustic signal;

receiving the first acoustic signal by a microphone to form a first electric response signal;

using the first electric response signal to obtain level and phase information of the loudspeaker system; and

wherein the method further comprises adjusting the level and phase of at least one of the first loudspeaker and the second loudspeaker.

5. The method according to claim 1 , wherein the measuring the compensated room response comprises:

generating the second test signal;

providing the second test signal to the loudspeaker system to form a second acoustic signal;

receiving the second acoustic signal by a microphone to form a second electric response signal; and

using the second electric response signal to obtain frequency response of the loudspeaker system.

6. An apparatus configured to adjust a cross-over frequency of a loudspeaker system, the loudspeaker system comprising at least a first loudspeaker for frequencies below the cross-over frequency and a second loudspeaker for frequencies above the cross-over frequency, wherein the apparatus comprises:

a signal generator configured to generate a first test signal;

a level adjustment element configured to match a level of the first loudspeaker with the second loudspeaker by using the first test signal:

a room response analysing element configured to obtain a room response on the basis of the first test signal by:

sweeping a frequency range of the first test signal;

providing the first test signal to the first loudspeaker and the second loudspeaker to produce audible signals sweeping the frequency range;

receiving the audible signals; and

computing an estimate of summed total harmonic distortion on the basis of the received signals;

a compensating element configured to compensate the room response in the loudspeaker system on the basis of the first test signal;

wherein the signal generator is further configured to generate a second test signal; and

the room response analysing element is further configured to obtain a compensated room response using the second test signal;

wherein the apparatus further comprises:

a frequency determination element for determining a maximum frequency for the first loudspeaker and a minimum frequency for the second loudspeaker, wherein the frequency determination element is configured to:

examine a frequency response of the first loudspeaker;

examine a frequency response of the second loudspeaker;

searching a roll-off point of the first loudspeaker representing the maximum frequency;

searching a roll-off point of the second loudspeaker representing the minimum frequency;

a cross-over frequency determination element configured to find a cross-over frequency between the minimum and maximum frequency that results in a minimum cumulative total harmonic distortion energy at one or more sound pressure levels by simulating a number of frequencies between the minimum and maximum frequency and measuring the cumulative total harmonic distortion energy at each of the frequencies.

7. The apparatus according to claim 6 , wherein the apparatus is further configured to adjust the frequency response of the loudspeaker system to compensate the room response.

8. An apparatus for adjusting a cross-over frequency of a loudspeaker system, the loudspeaker system comprising at least a first loudspeaker for frequencies below the cross-over frequency and a second loudspeaker for frequencies above the cross-over frequency, wherein the apparatus comprises:

means for matching a level of the first loudspeaker with the second loudspeaker using a first test signal configured to:

obtain a room response on the basis of the first test signal by:

sweep a frequency range of the first test signal;

provide the first test signal to the first loudspeaker and the second loudspeaker to produce audible signals sweeping the frequency range;

receive the audible signals; and

compute an estimate of summed total harmonic distortion on the basis of the received signals

means for compensating a room response in the loudspeaker system on the basis of the first test signal;

means for measuring the compensated room response using a second test signal;

means for determining a maximum frequency for the first loudspeaker by examining a frequency response of the first loudspeaker and determining a roll-off point of the first loudspeaker;

means for determining a minimum frequency for the second loudspeaker by examining a frequency response of the second loudspeaker and determining a roll-off point of the second loudspeaker; and

means for searching a cross-over frequency between the minimum and maximum frequency that results in a minimum cumulative total harmonic distortion energy at one or more sound pressure levels by simulating a number of frequencies between the minimum and maximum frequency and measuring the cumulative total harmonic distortion energy at each of the frequencies.

9. The apparatus according to claim 8 , wherein the apparatus further comprises means for adjusting the frequency response of the loudspeaker system to compensate the room response.

10. The apparatus according to claim 8 , wherein the means for matching the level of the first loudspeaker with the second loudspeaker comprises:

means for generating the first test signal;

means for providing the first test signal to the loudspeaker system to form a first acoustic signal;

means for receiving the first acoustic signal by a microphone to form a first electric response signal; and

means for using the first electric response signal to obtain level information of the loudspeaker system;

wherein the apparatus further comprises means for adjusting the level of at least one of the first loudspeaker and the second loudspeaker.

11. The apparatus according to claim 8 , wherein the means for matching the level of the first loudspeaker with the second loudspeaker comprises:

generating the first test signal;

providing the first test signal to the loudspeaker system to form a first acoustic signal;

receiving the first acoustic signal by a microphone to form a first electric response signal; and

using the first electric response signal to obtain level and phase information of the loudspeaker system;

wherein the apparatus further comprises means for adjusting the level and phase of at least one of the first loudspeaker and the second loudspeaker.

12. The apparatus according to claim 8 , wherein the means for measuring the compensated room response comprises:

means for generating the second test signal;

means for providing the second test signal to the loudspeaker system to form a second acoustic signal;

means for receiving the second acoustic signal by a microphone to form a second electric response signal; and

means for using the second electric response signal to obtain frequency response of the loudspeaker system.