I wear ear plugs every time that I ride, except for the 12 mile trip to work and other short jaunts.
Maybe your definition's different from mine, but a good set of earplugs will block a fair amount of the higher-frequency components of exhaust and wind noise from riding at speed and the lower-frequency components of wind buffeting and some of the impact of exhaust. Ear plugs have differing response curves. For example, shooters' plugs differ from most professional riders' plugs because they have to contend with short duration, very high amplitude sounds (mine have a small plate/valve) as opposed to the more continual sounds while riding . Even the cheaper foam-type plugs will cut wind/bike noise from the (roughly) 115 dB at highway speed to a less-destructive 85, due to a fairly broad-band 30 dB cut.earplugs do NOT block the bike related sounds.