Once noise is seen to fall unequally in more than one direction at once, a fair distribution can no longer be read off a single map. Two intuitive fixes fail; what replaces them is a standard with several axes.
The sound arriving at the façade. Foundational, but a single averaged reading is a weak proxy for harm.
Do not load the heaviest exposure onto those least able to keep it out.The conversion of a given noise into lost health. Worse baseline health and overlapping exposures make the same decibel cost more.
Protect the most susceptible before the most exposed.The reach of restorative sound — a restful bedroom, a calm park nearby, the plain ability to escape.
Treat quiet as a good that is not rationed by income.The resources to obtain quiet and recover from noise — glazing, barriers, mobility, bodily reserve.
Measure success by whether the least able to secure quiet have been helped to it.The multi-axis standard poses two further questions: whether the quiet it asks for is worth its price (the economics), and why instruments tuned to one averaged number at the façade so reliably miss susceptibility and access (the governance).