Active acoustic control apparatus

1. An active acoustic control apparatus comprising:

an alert sound signal generator configured to generate an alert sound signal representing an alert sound, which calls attention of a pedestrian;

an alert sound output device configured to output the alert sound to an outside of a vehicle in accordance with the alert sound signal;

a cancellation sound signal generator configured to generate a cancellation sound signal representing a cancellation sound to cancel the alert sound, which has been transferred from the outside of the vehicle to an inside of the vehicle, at a sound cancellation target position inside the vehicle; and

a cancellation sound output device configured to output the cancellation sound to the sound cancellation target position in accordance with the cancellation sound signal,

wherein the cancellation sound signal generator is configured to detect change of a transfer characteristic from the alert sound output device to the sound cancellation target position and to vary an output characteristic of the cancellation sound depending on the change of the transfer characteristic.

2. The active acoustic control apparatus according to claim 1 , wherein the cancellation sound signal generator is configured to detect the change of the transfer characteristic corresponding to an opened/closed state of at least one window or roof of the vehicle.

3. The active acoustic control apparatus according to claim 2 , wherein the cancellation sound signal generator starts the generation of the cancellation sound in response to change from the closed state to the opened state of the window or the roof, and stops the generation of the cancellation sound in response to change from the opened state to the closed state of the window or the roof.

4. The active acoustic control apparatus according to claim 2 , wherein the cancellation sound signal generator includes a fixed filter having a predetermined filter coefficient and selectively changes the filter coefficient depending on the opened/closed state of the window or the roof.

5. The active acoustic control apparatus according to claim 1 ,

wherein the alert sound is a sound independent of a rotational frequency of a driving motor for the vehicle, and

wherein the cancellation sound signal generator is configured to generate the cancellation sound signal in accordance with the alert sound signal.

6. The active acoustic control apparatus according to claim 5 , wherein the alert sound comprises at least one of chimes, a melody, a single tone, a chord sound, and a sound causing the pedestrian to recall a running state of the vehicle.

7. An active acoustic control apparatus comprising:

an alert sound signal generator configured to generate an alert sound signal representing an alert sound to call attention of a pedestrian;

an alert sound output device configured to output the alert sound to an outside of a vehicle in accordance with the alert sound signal;

a cancellation sound signal generator configured to generate a cancellation sound signal representing a cancellation sound to cancel, at a sound cancellation target position inside the vehicle, a transferred alert sound transferred from the outside of the vehicle to an inside of the vehicle;

a cancellation sound output device configured to output the cancellation sound to the sound cancellation target position in accordance with the cancellation sound signal;

a detector configured to detect change in a transfer characteristic from the alert sound output device to the sound cancellation target position; and

a controller configured to control an output characteristic of the cancellation sound depending on the change in the transfer characteristic.

8. An active acoustic control apparatus comprising:

alert sound signal generation means for generating an alert sound signal representing an alert sound to call attention of a pedestrian;

alert sound output means for outputting the alert sound to an outside of a vehicle in accordance with the alert sound signal;

cancellation sound signal generation means for generating a cancellation sound signal representing a cancellation sound to cancel, at a sound cancellation target position inside the vehicle, a transferred alert sound transferred from the outside of the vehicle to an inside of the vehicle;

cancellation sound output means for outputting the cancellation sound to the sound cancellation target position in accordance with the cancellation sound signal;

detection means for detecting change in a transfer characteristic from the alert sound output device to the sound cancellation target position; and

control means for controlling an output characteristic of the cancellation sound depending on the change in the transfer characteristic.

9. The active acoustic control apparatus according to claim 3 , wherein the cancellation sound signal generator includes a fixed filter having a predetermined filter coefficient and selectively changes the filter coefficient depending on the opened/closed state of the window or the roof.

10. The active acoustic control apparatus according to claim 2 ,

wherein the alert sound is a sound independent of a rotational frequency of a driving motor for the vehicle, and

wherein the cancellation sound signal generator is configured to generate the cancellation sound signal in accordance with the alert sound signal.

11. The active acoustic control apparatus according to claim 3 ,

wherein the alert sound is a sound independent of a rotational frequency of a driving motor for the vehicle, and

wherein the cancellation sound signal generator is configured to generate the cancellation sound signal in accordance with the alert sound signal.

12. The active acoustic control apparatus according to claim 4 ,

wherein the alert sound is a sound independent of a rotational frequency of a driving motor for the vehicle, and

wherein the cancellation sound signal generator is configured to generate the cancellation sound signal in accordance with the alert sound signal.

13. The active acoustic control apparatus according to claim 9 ,

wherein the alert sound is a sound independent of a rotational frequency of a driving motor for the vehicle, and

wherein the cancellation sound signal generator is configured to generate the cancellation sound signal in accordance with the alert sound signal.

14. The active acoustic control apparatus according to claim 10 , wherein the alert sound comprises at least one of chimes, a melody, a single tone, a chord sound, and a sound causing the pedestrian to recall a running state of the vehicle.

15. The active acoustic control apparatus according to claim 11 , wherein the alert sound comprises at least one of chimes, a melody, a single tone, a chord sound, and a sound causing the pedestrian to recall a running state of the vehicle.

16. The active acoustic control apparatus according to claim 12 , wherein the alert sound comprises at least one of chimes, a melody, a single tone, a chord sound, and a sound causing the pedestrian to recall a running state of the vehicle.

17. The active acoustic control apparatus according to claim 13 , wherein the alert sound comprises at least one of chimes, a melody, a single tone, a chord sound, and a sound causing the pedestrian to recall a running state of the vehicle.