4 ms·
Oops, thanks. Because this requires more digging: the detailed specs come from UNECE Regulation 138 which can be found at https://www.unece.org/fileadmin/DAM/t
by pgeorgi 7y ago
Oops, thanks.
Because this requires more digging: the detailed specs come from UNECE Regulation 138 which can be found at https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2017/R138r1e.pdf https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs... (which also seems to be the current edition at this time, according to the special interest database at https://globalautoregs.com/rules/205-quiet-road-transport-vehicles https://globalautoregs.com/rules/205-quiet-road-transport-ve...).
The relevant parts are 6.2.1.2 and the table in 6.2.8, and they lay out a minimum sound level of 56dB(A) at 2m distance to the car (PP' line, as defined in the appendix to Annex 3) at 20km/h, that must be spread out over two of the bands in the table (at least one <= 1600Hz)
In other tables on the net, I get 50dB as the "minimum street noise", 70dB for a car at 10m distance and 45-60dB for a quiet-to-normal conversation at 1m distance. 56dB at 2m still seems relatively muted in that context.
- zaroth 7y agoNo, 70dB is a vacuum cleaner level noise. 60dB is not a single conversation, more like a restaurant full of people. But most importantly, perceived volume is highly relative. In a noisy urban environment that god-awful drivetone might not horrible, but it still has to be noticeable. After all, the busy urban environment is exactly where it's theoretically supposed to be helping people notice the car! But how about when someone is driving through their suburban condo complex coming home after a late night of work?