. . . . . "Doppler effect"@en-us . "change in the apparent frequency of a wave as observer and source move toward or away from each other"@en-us . "11513179-n"^^ . "107838216"@en-us . "0"^^ . . "110771008"@en-us . "Doppler shift"@en-us . . . "0"^^ . "Doppler effect"^^ . "111513179"^^ . . .