WE CLAIM:
[Claim 1]
An acoustic device that provides a stereophonic effect to a
driver of a mobile object, the acoustic device comprising:
5 a plurality of speakers mounted on a steering wheel that
controls a traveling direction of the mobile object;
a steering angle detection unit configured to detect a steering angle of the steering wheel; and
a signal output unit configured to output a plurality of output 10 signals obtained by performing, on a sound signal, a process relating to the stereophonic effect and depending on the steering angle, respectively to the plurality of speakers.
[Claim 2]
15 The acoustic device according to claim 1,
wherein the signal output unit includes:
a sound signal storage unit configured to store the sound signal;
a control unit configured to determine filter coefficients for the 20 process depending on the steering angle; and
a signal processing unit configured to perform the process on the sound signal using the filter coefficients, to generate the plurality of output signals.
25 [Claim 3]
The acoustic device according to claim 2, wherein the signal processing unit is configured to further perform a crosstalk cancellation process on the sound signal.
30 [Claim 4]
The acoustic device according to claim 1, wherein the signal output unit includes:
an output signal storage unit configured to store a plurality of signal groups respectively associated with a plurality of different

a signal selection unit configured to select one signal group corresponding to the steering angle detected by the steering angle detection unit, from the plurality of signal groups, and
the plurality of signal groups each include the plurality of 5 output signals.
[Claim 5]
The acoustic device according to any one of claim 1 to claim 4,
wherein the plurality of output signals output by the signal
10 output unit in the case where the steering angle is not 0 are obtained
by performing the process for providing a same stereophonic effect
as in the case where the steering angle is 0.
[Claim 6]
15 The acoustic device according to any one of claim 1 to claim 5,
wherein the signal output unit is configured to, in the case where the steering angle is greater than a predetermined angle, output the plurality of output signals that do not provide the stereophonic effect. 20
[Claim 7]
The acoustic device according to any one of claim 1 to claim 6,
wherein the signal output unit is configured to, in the case
where a variation of the steering angle per unit time is greater than
25 a predetermined value, output the plurality of output signals that do
not provide the stereophonic effect.
[Claim 8]
The acoustic device according to any one of claim 1 to claim 7,
30 wherein at least two speakers of the plurality of speakers are
arranged on a same arc centered on a rotation axis of the steering wheel, and
the at least two speakers are at a same vertical position in the case where the steering angle is 0.

[Claim 9]
The acoustic device according to any one of claim 1 to claim 8, wherein at least two speakers of the plurality of speakers are arranged symmetrically with respect to a point on a rotation axis of 5 the steering wheel.
[Claim 10]
The acoustic device according to any one of claim 1 to claim 9,
wherein the plurality of speakers are arranged symmetrically
10 with respect to a vertical plane including a rotation axis of the
steering wheel in the case where the steering angle is 0.
[Claim 11]
A mobile object comprising:
15 the acoustic device according to any one of claim 1 to claim
10; and
the steering wheel.