Usually, the background noise of office corridor is about 48-52 dB, and that of supermarket is about 58-63 dB, and that of busy section is about 70-75 dB. Considering that the scene may be very confused in the event of an accident, the background noise should not be estimated too low for the need of emergency broadcasting, even if the broadcasting service area is an office building. Therefore, as a general consideration, in addition to busy and lively places, background noise may be roughly regarded as 65-70dB (except in special cases). According to this calculation, the sound pressure level in the broadcast coverage area should be above 80-85 dB.
DepuisHaut-parleurs adresse publique are usually distributed, the sound pressure level in the adress coverage area can be approximately considered as the contribution of a single public adress speakers
. Selon la théorie de l'électroacoustique pertinente, le niveau de pression acoustique SPL dans la zone de couverture du haut-parleur a les relations suivantes avec le niveau de sensibilité LM du haut-parleur, la puissance P alimentée au haut-parleur, le point d'écoute et la distance r du haut-parleur, etc.
SPL=LM 10lgP-20lgrdB(1)
Le niveau de sensibilité du haut-parleur de la variole varie de 88 à 93 dB et la puissance nominale est de 3 à 10 W. Calculé par 90dB/8W, le niveau de pression acoustique à 8m du haut-parleur est d'environ 81dB. La contribution du groupe sonore réfléchi précoce n'est pas prise en compte dans le calcul ci-dessus. En intérieur, la contribution du groupe sonore réfléchi tôt et des haut-parleurs adjacents peut augmenter le niveau de pression acoustique d'environ 2 à 3 dB.
According to the above approximate calculation, the ceiling loudspeakers can be arranged evenly at a distance of 5-8 m in a venue whose ceiling is not higher than 3 m. If only background music is considered and emergency broadcasting is not considered, the distance can be increased to 8-12 M. In addition, the design and installation code for fire accident broadcasting in mainland China (hereinafter referred to as "code").
Il n'y a fondamentalement pas de premiers groupes sonores réfléchissants dans les espaces extérieurs, et la couverture efficace d'un seulHaut-parleur de sonorisation can only be taken as the lower limit calculated above. Since the lower limit corresponds to a very short distance, in principle, a sound column composed of multiple speakers should be used. The sound pressure level can be increased by 3dB for every doubling of the signal power to the speaker group (such as the sound column) provided that the group is acceptable. From 1 to 2 is double; from 2 to 4 is double. In addition, the sound pressure level will decrease by 6 dB for every doubling of distance. According to the above rules, it is not difficult to calculate the configuration distance of outdoor sound column.