The letter "Xx" can have 3 sounds - "ks", "gz" and "z".
Note: in typical spoken English the sounds "ks" and "gz" often sound the same.

These words have the "ks" sound. When "x" is in the stressed syllable we use the sound "ks":

  • exchange, extra, exercise
  • expect, wax, fox, box
  • fix, relax, express

These words have the "gz" sound. When "x" is not in the stressed syllable we use the sound "gz":

  • exam, exact, executive
  • exist, exert, exhaust

These words have the "z" sound. Generally, words that start with the letter Xx are pronounced with the sound of the letter "Zz":

  • xenophobia, xenon
  • xylophone, xerox

Practice
Practice reading the following sentences out loud, concentrate on pronunciation of the "Xx" sounds.
The red letters are pronounced with the "ks" sound.
The green letters are pronounced with the "gz" sound.
The blue letters are pronounced with the "Zz" sound

  • I like to exercise in the morning and relax in the evening, sometimes I relax by playing my xylophone.
  • The executive exited the room in a hurry because his ex-wife came into the room.
  • I expected the exam to be hard, and when I saw my score I felt exulted!
  • The express bus creates too much smelly exhaust, it should be examined and fixed.

A reminder: the "gs" and "ks" sounds often sound the same. So don't worry about perfect pronunciation of these two sounds.