If you will allow me to make an assumption, you do not have a 5.1 surround system connected to your DVD player. This is a common experience with users of a standard TV or stereo receiver if a movie is being presented in 5.1.
In a surround sound system the center channel speaker provides almost all the vocal tracks while the side channels will provide music and some background noises. You'll still be able to hear the voices in your side speakers, but it will be muted and over powered by music or sound effects.
Some DVD players allow you to "Downmix" the surround signal to stereo. You might want to look around your sound setup on the DVD player or check your owners manual.
Can't seem to be able to connect my Emerson EWD7003 DVD Payer to my RCA entertainment series Tv #2...
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Can't seem to be able to connect my Emerson EWD7003 DVD Payer to my RCA entertainment series Tv #2 which is connected to satellite Dishnetwork