The image concept is undergoing a profound change with the
advent of hybrid vehicles. Conventional hybrids such as Toyota’s
Prius have become a common sight, and major vehicle OEMs are
developing a next generation of hybrids that can be plugged in to
extend their electric range and greatly improve fuel economy.4
Entirely electric vehicles are also available on the market,5,6,7,8
while other companies work toward building the electric vehicle
support network and infrastructure.9 The sound and vibration
signature of electric and hybrid vehicles in general is quite different
from vehicles powered by internal combustion engines, but
so are customers’ expectations, since the degree of “greenness”
of the vehicle weighs the fuel efficiency/fuel independence more
heavily than look and feel.
From a sound quality standpoint, there are two main design
challenges:
• Interior noise, which needs to provide an image of quality and
“cool”
• Exterior noise, first to ensure safety and next to be used for
brand recognition
Quoting one of the several excellent papers authored by N. Otto4
at Ford, “the lack of engine noise in electric vehicles is a doubleedged