Sound processing device, vehicle and sound processing method

1. A sound processing device, comprising:

a sound source that outputs a sound signal to a first speaker for a vehicle exterior and a second speaker for a vehicle interior that are provided in the vehicle, the sound signal being common to the first speaker and the second speaker;

a notification sound controller that outputs a signal corresponding to a notification sound for notifying approach of the vehicle to the first speaker based on the sound signal output from the sound source; and

an acceleration sound controller that outputs a signal corresponding to an acceleration sound of the vehicle to the second speaker based on the sound signal output from the sound source,

wherein

the acceleration sound controller processes the sound signal output from the sound source to monotonically increase a sound pressure obtained by summing a sound pressure of the notification sound leaking into the vehicle interior and a sound pressure of the acceleration sound output into the vehicle interior in accordance with acceleration of the vehicle, and monotonously decrease the sound pressure obtained by summing in accordance with deceleration of the vehicle.

2. The sound processing device according to claim 1 , further comprising:

a filter that has a pass band that is a predetermined frequency band, wherein

the notification sound controller outputs a signal corresponding to the notification sound to the first speaker based on the sound signal output from the sound source and passing through the filter.

3. The sound processing device according to claim 1 , wherein

the notification sound controller and the acceleration sound controller each processes the sound signal output from the sound source, so as to change a pitch of the notification sound and a pitch of the acceleration sound at a same ascending rate in accordance with acceleration of the vehicle, respectively, and change the pitch of the notification sound and the pitch of the acceleration sound at a same descending rate in accordance with deceleration of the vehicle, respectively.

4. The sound processing device according to claim 1 , further comprising:

a failure detector that detects a failure of the first speaker, wherein

when the acceleration sound controller detects the failure of the first speaker, the acceleration sound controller outputs a sound signal indicating that the first speaker has failed to the second speaker.

5. A vehicle, comprising:

the sound processing device according to claim 1 ;

the first speaker; and

the second speaker.

6. A sound processing method, comprising:

outputting, by a sound source, a sound signal to a first speaker for a vehicle exterior and a second speaker for a vehicle interior that are provided in the vehicle, the sound signal being common to the first speaker and the second speaker;

outputting, by a notification sound controller, a signal corresponding to a notification sound for notifying an approach of the vehicle based on the sound signal output;

outputting, by an acceleration sound controller, a signal corresponding to an acceleration sound of the vehicle to the second speaker based on the sound signal output; and

processing, by the acceleration sound controller, the sound signal output to monotonically increase a sound pressure obtained by summing a sound pressure of the notification sound leaking into the vehicle interior and a sound pressure of the acceleration sound output into the vehicle interior in accordance with acceleration of the vehicle, and monotonously decrease the sound pressure obtained by summing in accordance with deceleration of the vehicle.