ACOUSTIC SIGNAL OUTPUT DEVICE
Provided is an acoustic signal output device including a driver unit that emits a first acoustic signal to one side and emit a second acoustic signal having an opposite phase to the first acoustic signal to the other side, a first waveguide that has one end connected to the one side of the driver unit and leads out the first acoustic signal, a second waveguide that has one end connected to the other side of the driver unit and leads out the second acoustic signal, and a housing including a first hollow portion to which the other end of the first waveguide is connected and a second hollow portion to which the other end of the second waveguide is connected. Here, the first hollow portion is provided with a first sound hole that leads out the first acoustic signal to the outside, and the second hollow portion is provided with second sound holes that lead out the second acoustic signal to the outside. An attenuation rate of the first acoustic signal at a second point with reference to a predetermined first point, where the first acoustic signal arrives at the first point and the second point is farther from the acoustic signal output device than the first point, is equal to or less than a predetermined value smaller than an attenuation rate due to air propagation. Alternatively, an attenuation amount of the first acoustic signal at the second point with reference to the first point is equal to or more than a predetermined value larger than an attenuation amount due to air propagation.
1 . An acoustic signal output device, comprising:
a driver unit that emits a first acoustic signal to one side and emits a second acoustic signal to another side;
a first waveguide that has one end connected to the one side of the driver unit and leads out the first acoustic signal;
a second waveguide that has one end connected to the other side of the driver unit and leads out the second acoustic signal; and
a housing including a first hollow portion to which another end of the first waveguide is connected and a second hollow portion to which another end of the second waveguide is connected,
wherein
a wall portion of the first hollow portion is provided with a single or a plurality of first sound holes that leads out the first acoustic signal introduced into the first hollow portion by the first waveguide to an outside,
a wall portion of the second hollow portion is provided with a single or a plurality of second sound holes that leads out the second acoustic signal introduced into the second hollow portion by the second waveguide to the outside, and
an attenuation rate of the first acoustic signal at a second point with reference to a predetermined first point where the first acoustic signal arrives and farther from the acoustic signal output device than the first point when the first acoustic signal is emitted from the first sound holes and the second acoustic signal is emitted from the second sound holes is designed to be equal to or less than a predetermined value smaller than an attenuation rate due to air propagation of an acoustic signal at the second point with reference to the first point, or
an attenuation amount of the first acoustic signal at the second point with reference to the first point is designated to be equal to or more than a predetermined value larger than an attenuation amount of the acoustic signal due to air propagation at the second point with reference to the first point.
2 . The acoustic signal output device according to claim 1 , wherein
the first hollow portion and the second hollow portion are arranged on a same axis,
the first sound holes open toward a first direction along the axis, and
the second sound holes open toward a second direction between the first direction and a direction opposite to the first direction.
3 . The acoustic signal output device according to claim 2 , wherein
a central region of the first hollow portion and a central region of the second hollow portion are arranged on the axis,
positions of the first sound holes are biased to an eccentric position deviated from the axis, and
a human auditory sensitivity for an acoustic signal having a resonance frequency equal to or higher than a predetermined frequency of the housing in which the positions of the first sound holes are biased to the eccentric position is lower than a human auditory sensitivity for an acoustic signal having a resonance frequency equal to or higher than the predetermined frequency of the housing in a case where it is assumed that the first sound holes are provided at a center position that is a position on the axis, and/or
peak sharpness at the predetermined frequency or more of a magnitude of the first acoustic signal emitted from the first sound holes and/or the second acoustic signal emitted from the second sound holes of the housing in which the positions of the first sound holes are biased to the eccentric position is blunter than peak sharpness at the predetermined frequency or more of a magnitude of the first acoustic signal emitted from the first sound holes and/or the second acoustic signal emitted from the second sound holes of the housing in a case where it is assumed that the first sound holes are provided at a center position.
4 . The acoustic signal output device according to claim 2 , wherein
a central region of the first hollow portion and a central region of the second hollow portion are arranged on a same axis,
the acoustic signal output device comprising:
a first joining member that is arranged on the axis, opens toward the first direction along the axis, and emits the first acoustic signal introduced from the other end of the first waveguide toward the first direction inside the first hollow portion; and
a second joining member that is arranged on the axis, opens toward the first direction along the axis, and emits the second acoustic signal introduced from the other end of the second waveguide toward the first direction inside the second hollow portion.
5 . The acoustic signal output device according to claim 1 , further comprising an acoustic absorbent in which a sound absorbing rate for a sound absorbing material of a first frequency is larger than a sound absorbing rate for an acoustic signal of a second frequency,
wherein
the first frequency is higher than the second frequency, and
the sound absorbing material is provided on the other side of the driver unit and/or is provided inside the second waveguide, and/or is provided at an end of the second waveguide, and/or is provided in at least one of the second sound holes, and/or is provided inside the second hollow portion.