Phonetics and the IPA 2, Exercise 1: voiced or voiceless?

Voiceless (no buzz under the fingers): [s] [f] [ʃ] [θ]
Voiced (buzz):                         [z] [v] [ʒ] [ð]

Pairs (same place and manner, only voicing differs):
  [f] / [v]   fan / van
  [θ] / [ð]   thin / this
  [s] / [z]   sip / zip
  [ʃ] / [ʒ]   mission / vision   (RP and General American: [ˈmɪʃn̩] / [ˈvɪʒn̩])

Takeaway: sustain the sound (don't add a vowel after it) or the vowel's buzz
will fool you. Say "ssss" and "zzzz", not "sa" and "za".