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.
तब सेसार्वजनिक अभिमुखता वक्ताओं 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
. प्रासंगिक इलेक्ट्रोध्वनिक सिद्धांत के अनुसार, स्पीकर कवरेज क्षेत्र में ध्वनि दबाव स्तर का स्तर स्पीकर के संवेदनशीलता स्तर के साथ निम्नलिखित संबंध हैं, ध्वनि बिंदु और स्पीकर की दूरी, आदि।
SPL=LM 10lgP-20lgrdB(1)
चेचक लाउडस्पीकर का संवेदनशीलता स्तर 88 से 93 डीबी तक होता है, और रेटेड पावर 3 से 10 W होती है। 90db/8w द्वारा गणना की गई, लाउडस्पीकर से 8 मीटर की दूरी पर ध्वनि दबाव स्तर लगभग 81db है। प्रारंभिक परिलक्षित ध्वनि समूह के योगदान को उपरोक्त गणना में नहीं माना जाता है। इनडोर, प्रारंभिक परिलक्षित ध्वनि समूह और आसन्न लाउडस्पीकर का योगदान ध्वनि दबाव स्तर लगभग 2-3 डीबी तक बढ़ा सकता है।
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").
बाहरी क्षेत्रों में मूल रूप से प्रारंभिक चिंतनशील ध्वनि समूह नहीं हैं, और एक एकल का प्रभावी कवरेजपब्लिक एड्रेस स्पीकर 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.