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.
Desde queAltavoces adress públicos 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
... De acuerdo con la teoría electroacústica relevante, el nivel de presión de sonido SPL en el área de cobertura del altavoz tiene las siguientes relaciones con el nivel de sensibilidad LM del altavoz, la potencia P alimentada al altavoz, el punto de escucha y la distancia r del altavoz, etc.
SPL=LM 10lgP-20lgrdB(1)
El nivel de sensibilidad del altavoz de la viruela varía de 88 a 93 dB, y la potencia nominal es de 3 a 10 W. Calculado por 90dB/8W, el nivel de presión de sonido a 8m del altavoz es de aproximadamente 81dB. La Contribución del Grupo de sonido reflejado temprano no se considera en el cálculo anterior. En interiores, la contribución del Grupo de sonido reflejado temprano y los altavoces adyacentes puede aumentar el nivel de presión del sonido en aproximadamente 2-3 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").
Básicamente, no hay grupos de sonido reflectantes tempranos en áreas al aire libre, y la cobertura efectiva de un soloAltavoz de megafonía 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.