Like a lot of languages, in English the written ‘s’ is represented by a sibilant sound. This sound is either voiced or voiceless depending on which word it is used in. The voiced sound is also often represented by a ‘z’.

/s/ = unvoiced alveolar fricative (snake, this, someone)

/z/ = voiced alveolar fricative (these, tom’s, fizz)

There are other similar sounds such as /sh/ and /zh/ which can be difficult to alternate between. The s tongue twisters below will help build flexibility when going between these sounds.

Practise regularly to see improvement in your pronunciation.

Good luck!