ACOUSTIC SIGNAL OUTPUT DEVICE
There is provided an acoustic signal output device that does not completely block the ear canal and is capable of suppressing sound leakage into the surroundings. There is provided an acoustic signal output device 10 including a structure portion provided with one or more sound holes 121 a to emit an acoustic signal AC 1 to outside and one or more sound holes 123 a to emit an acoustic signal AC 2 to the outside. The sound holes 121 a are each positioned at an eccentric location offset in the B1-direction from a central axis of the structure portion. A sound pressure level of the acoustic signal AC 2 that is emitted from the sound holes 123 a into a first space is lower than a sound pressure level of the acoustic signal AC 2 that is emitted from the sound holes 123 a into a second space. Here, the first space is a space positioned on the B1-direction side relative to the sound holes 121 a , the second space is a space positioned on the B2-direction side relative to the sound holes 121 a , and the B2 direction contains an opposite direction component of the B1 direction.
1 . An acoustic signal output device comprising:
a structure portion provided with one or more first sound holes to emit a first acoustic signal to outside and one or more second sound holes to emit a second acoustic signal to the outside, wherein
the first sound holes are each positioned at an eccentric location offset in a first direction from a central axis of the structure portion,
a sound pressure level of the second acoustic signal that is emitted from the second sound holes into a first space is lower than a sound pressure level of the second acoustic signal that is emitted from the second sound holes into a second space,
the first space is a space positioned on a first direction side relative to the first sound holes,
the second space is a space positioned on a second direction side relative to the first sound holes, and the second direction contains an opposite direction component of the first direction, and
the acoustic signal output device is designed such that
in a case where the first acoustic signal is emitted from the first sound holes and the second acoustic signal is emitted from the second sound holes, an attenuation factor of the first acoustic signal at a second point with respect to a first point is equal to or lower than a predefined value that is smaller than an attenuation factor associated with air conduction of an acoustic signal at the second point with respect to the first point, wherein the first point is a predefined point that is reached by the first acoustic signal, and the second point is farther from the acoustic signal output device than the first point is, or that
an amount of attenuation of the first acoustic signal at the second point with respect to the first point is equal to or higher than a predefined value that is greater than an amount of attenuation associated with air conduction of an acoustic signal at the second point with respect to the first point.
2 . The acoustic signal output device according to claim 1 , wherein
a total area of opened ends of the second sound holes that face the first space is smaller than a total area of opened ends of the second sound holes that face the second space.
3 . The acoustic signal output device according to claim 1 , wherein
the structure portion is provided with a plurality of the second sound holes, and
a sound pressure level of the second acoustic signal that is emitted from an opened end facing the first space among opened ends of the second sound holes is lower than a sound pressure level of the second acoustic signal that is emitted from an opened end facing the second space among the opened ends of the second sound holes.
4 . The acoustic signal output device according to claim 1 , wherein
at least a portion of an outer surface area surrounding opened ends of the first sound holes is convex-shaped, and
the outer surface area includes a first area and a second area protruding further than the first area, the outer surface area being shaped so as to direct the first acoustic signal emitted from the first sound holes to a first area side.
5 . The acoustic signal output device according to claim 4 , wherein
the opened ends of the first sound holes face a space surrounded by the second area, and
the first area side of the space surrounded by the second area is open outwardly from an outer periphery of the space surrounded by the second area.
6 . The acoustic signal output device according to claim 4 , wherein
the first area is positioned on the first direction side of the second area.
7 . The acoustic signal output device according to claim 4 , wherein
the acoustic signal output device is configured such that
when the structure portion is attached to a user's body,
the second area is supported in contact with some portion of the body, and
the first area is positioned on ear canal side without causing contact of the opened ends of the first sound holes and the first area with at least part of the body.