Sounds with vocal chord vibration are voiced and sounds without vocal chord vibration are voiceless.
Contrast the sounds of the letters v and f. Place your fingers on your throat and make the sounds. You should feel a vibration when you make the V sound and no vibration when you make the F sound.
V is voiced and F is voiceless.
Try this with the other letters and you will “feel” the difference between a voiced and a voiceless consonant (or sound).
The Voiced Sounds in English:
B D G J L M N ŋ(ng)
R V Z ð (th in the) all vowels
The Voiceless Sounds in English:
F H K P S T SH CH θ (th in think)