4/19/2023 0 Comments Painttool sai cmyk![]() ![]() So, given we know the energy input of the speakers (80,000 watts), we can establish the sensitivity required to produce that level of sound. That represents 11.551 doublings (2^11.551) - a sound pressure level difference of 69.306 decibels or in other words, the speaker needs to be outputting 149.306 decibels at a distance of one meter. A peak of 80 decibels is probably reasonable, (dialogue is going to be output at less power than the 'maximum’) at a distance of 3000 meters. We don’t know what the sensitivity of Frank’s TV is, but we can work backwards to find what we need. So we need at least 32 watts of power for this speaker. So if we have a speaker with a sensitivity of 88 and want to hear 100 decibels (the maximum comfortable sound being around 105 decibels) ten meters away, then we have a sound pressure level difference of 12, or 4 doublings of power, as well as 3.332 doublings of distance, which means our sound pressure level at the reference distance needs to be an additional ~19.9 decibels higher, a total of almost 5 doublings of power. Likewise due to the square cube law every doubling of distance reduces the decibels by 6. As a rough rule, due to the logarithmic nature of the decibel, an increase of +3 decibels requires double the power. Speakers are, of course, capable of generating sounds more intense than their sensitivity rating, and those sounds propogate at longer distances. Figures in the high 80s to low 90s are typical. Speakers have a measure known as 'sound sensitivity’, which is equivalent to the decibels of sound produced by one watt of power at a distance of 1 meter. The answer to the second question is 'probably no’. In conclusion, I believe that the claim is credible assuming short-edge blocks are used, but at 6 kilometers (if we were to use long-edge Chicago-style blocks) it would stretch credibility that one would be able to enjoyably watch the Simpsons due to missing too many visual details for some jokes to land. According to this article, at 3 kilometers a person of typical visual acuity can make out two separate headlights on a car, which are (on average in the US) about 1.5 meters apart. ![]() So, the question becomes: at a distance of 3 kilometers, how well can someone of decent visual acuity (approaching 20/20 vision with or without the aid of standard eyewear) make out an object roughly 4 by 3 meters in size? We should also assume that the business of the city landscape is not a factor here and that the view of the screen is otherwise unobstructed by barriers and atmospheric conditions. ![]()
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