Sound Field Localization |
|
Keywords: Acoustic barrier-free, directional speaker, speaker array, acoustic PA |
|
Since sounds are waves that propagate in a 3 dimensional space, once emitted, they may propagate indefinitely as long as there are no obstacles. Besides, sound is not a mere physical phenomenon. Because it exerts a notable influence in human psychology, its diffusion becomes a significant social problem. Particular attention is needed when emitting sound in a public space as the sound doesn't reach only the target person. For other people, that sound becomes acoustic noise. The problem is not only the loudness of the sound. There are times when even sounds that have a very low amplitude (physically not loud) may generate an unpleasant feeling. Recently, there are attempts to use sound to convey information or guidance in order to make elderly or visually impaired people able to go downtown and use public transportation smoothly. For such cases, it's necessary to control sound emission to a specific place. This is not only because sound may become a nuisiance for those to whom the message is not directed to. An environment filled with voice messages of information and guidance actually becomes very dangerous to the elderly or the visually impaired. By building in the three dimensional space walls that prevent only sounds from going through, letting light and air through, sound field localization allows a sound output to be confined to a specific area; or record only sounds within a delimited space. This way, even difficulties related to low sounds can be controlled with the advantage that changes in the system's dimensions become unnecessary. |