Identify the word where the initial consonant is a voiceless sound

A voiceless sound is made without the vocal cords vibrating. “Cheese” starts with /tʃ/, which is voiceless.

“Joke” and “giraffe” both start with /dʒ/, and “zebra” starts with /z/. All three are voiced. Put a finger on your throat and you will feel the vibration.