Yeah I have no issues hearing an ICE vehicle coming from behind me when I'm on my bike. OTOH I have had many scared sudden encounters with an EV coming into my field of view.
Tyres on the road are white noise and barely noticeable. I don't know if they're louder than engines in terms of decibels as I've never measured either, but engines are definitely much more of a nuisance.
> As required by the PSEA, (1) this rule proposes to establish FMVSS No.141, Minimum Sound Requirements for Hybrid and Electric Vehicles, which would require [quiet vehicles] to produce sounds meeting the requirements of this standard. This proposed standard applies to EVs and to those HVs that are capable of propulsion in any forward or reverse gear without the vehicle's ICE operating. The PSEA requires NHTSA to establish performance requirements for an alert sound that is recognizable as motor vehicle in operation that allows blind and other pedestrians to reasonably detect a nearby EV or HV operating below the crossover speed. The crossover speed is the speed at which tire noise, wind noise, and other factors eliminate the need for a separate alert sound.
>[...]
> This standard will ensure that blind, visually-impaired, and other pedestrians are able to detect and recognize nearby hybrid and electric vehicles by requiring that hybrid and electric vehicles emit sound that pedestrians will be able to hear in a range of ambient environments and contain acoustic signal content that pedestrians will recognize as being emitted from a vehicle. The proposed standard establishes minimum sound requirements for hybrid and electric vehicles when operating under 30 kilometers per hour (km/h) (18 mph), when the vehicle's starting system is activated but the vehicle is stationary, and when the vehicle is operating in reverse.
The EU has established a similar rule as well, though I think they only require up to 12mph. Wikipedia says there's a 2008 study that confirms it but it's source link is broken:
> A separate 2008 study from Western Michigan University found that hybrids and conventional vehicles are equally safe when travelling more than about 20 miles per hour (32 km/h), because tire and wind noise generate most of the audible cues at those speeds. Hybrid cars were also tested safe when moving off at traffic lights and it was found that under this condition they do not pose a risk to pedestrians. All Prius models used in the study engaged their internal combustion engines when accelerating from a standstill and produced enough noise to be detected.[13]
