According to the average sound pressure level required by various places, select the sensitivity and listening distance of speaker. According to the above formula, the sound field electrical power required by the system can be calculated, which is the driving power required by the speaker.

① Determine the sound pressure level: For the language dilatation of the general hall, it is required to reach the average acoustic pressure level of about 75DB; the sound expansion of the music program requires a average sound pressure level of about 85DB. Considering the dynamic range of audio signals, it should be considered that the amount of 6DB and music sound expansion should be considered for language dilatation of the language. For the dilatation of the singing and dance hall, the maximum voltage level value in the GYJ25-86 table of the original radio and film and television department is generally based on the maximum volume value of the GYJ25-86. The sound pressure level LP determines that the dynamic amount of dynamic tunnel of the sound expansion system must be fully considered.

② Determine the sensitivity of the speaker: Before calculating, you must first determine the sensitivity of the speaker. It should be pointed out that speaker sensitivity is often related to the model of speakers. Once the sensitivity is determined, the speaker model is basically determined, and it should not be changed at will. The sensitivity of speaker has a great impact on the power required by the system. The sensitivity varies 3DB, and the electrical power is doubled. Therefore, the sensitivity of professional speakers should not be too low, and it should generally be 95 ~ 100DB. ③ Determine the listening distance: The farthest confession distance D, not more than 3 d, that is, the longest distance D should be less than 3 times the critical distance D.

④ Total electricity of the sound field: Many halls need to be confession, so the total power of the system should be the sum of the electricity required for all sound sources.