To raise the sound pressure of alarm sound, that is, the volume of the alarm sound by using sound output from the front of a speaker and sound output from the rear of the speaker.
An alarm device includes a detecting part 1, the speaker 2 and a housing 3. The detecting part 1 detects surrounding abnormal conditions. The speaker 2 outputs alarm sound and a voice to notify the abnormal conditions detected by the detecting part 1. Frequency bands are different between the alarm sound and the voice. In the housing 3, an internal space 36, a front side sound hole 34 and a lateral sound hole 37 are formed. The internal space 36 houses the speaker 2. A path from the front of the speaker 2 to the front side sound hole 34 is a first path, and a path from the rear of the speaker 2 to the lateral sound hole 37 through the internal space 36 is a second path. The housing 3 is formed so that a path difference between the second path and the first path may be 1/2 wavelength of a wavelength to a desired frequency included in the frequency band of the alarm sound.
| JPH01159797 | DISASTER PREVENTION FACILITY |
| JP2023055926 | SETTING DEVICE OF RADIO DISASTER PREVENTION SYSTEM |
KITADA KOSAKU
SAKAMOTO KOJI
SHIMADA YOSHITAKE
FUKUSHIMA MINORU
