Notes: /z/ looks much like /s/, a large burst of frication between 4000-8000 Hz. Unlike /s/, however, voicing usually continues through a /z/; look for glottal pulses showing at the 'voice bar' below 500 Hz, or in the frication.

A typical /z/ may look like:

Speaker: Tim Carmell
Word: the /z/ section of the word "zeal"