Hello Milton,   Suggestion ...

Hello Milton,

Suggestion would be at least 135 db but typically 140 dB and above. However, some considerations should be taken into account, such as:

• Attenuation caused by numerous source like ground effects, barriers due to building presence, etc. 
  Atmospheric refraction
• Sound absorption into the atmosphere
• People’s perception
• Building under construction
• distance between the speakers and population at risk since the sound level/loudness will decrease with the distance

Hope it helps

Regards,

Thomas