A down-to-earth, painless example of the Doppler shift principle is when you stand on a sidewalk and a police car speeds by in hot pursuit of a stolen motorcycle. The pitch of the police siren increases as the car approaches you and then drops sharply as it moves away.

Joel McNamara, GPS For Dummies, Wiley, 2004, p.50.

down-to-earth adjective
(approving) sensible and practical, in a way that is helpful and friendly:
She was friendly and down-to-earth and quickly put me at my ease. [OALD]

down-to-earth adj
practical and direct in a sensible honest way:
Fran’s a very friendly, down-to-earth person. [LDCE]