Sizing a Village Loudspeaker: Horn, Amplifier, Pole, and Solar Supply for a Market Square

A village that wants announcements heard across its market square needs four numbers: how loud the horn must be at the edge of the crowd, how many amplifier watts that takes, how high to mount it, and how much solar panel and battery the daily schedule consumes. This paper computes all four from stated assumptions: a market ambient of 65 dBA, a speech criterion of 75 dBA at the edge of the covered area, a horn sensitivity of 104 dB at 1 m for 1 W, and a paved-ground excess attenuation of 0.024/h dB per metre for pole height h. A 25 W amplifier gives 118.0 dB at 1 m and a coverage radius of 132.5 m on a 6 m pole; at the 40 m edge of a large market square the level is 85.7 dB, a margin of 10.7 dB above the criterion. Raising the pole from 4 m to 10 m moves the radius only from 128.9 m to 135.5 m. For a schedule of 2.0 announcement hours per day the system uses 82.5 Wh per day after losses, requiring a 24.4 Wp panel (a 50 Wp panel is chosen) and a 16.1 Ah battery at 12.8 V for two days of autonomy (a 20 Ah battery is chosen). The complete system prices at USD 1050. A passive megaphone, computed on the same criterion, reaches 9.8 m in market noise. SIMULATED, NOT MEASURED.