How to pronounce the 'ch sound' /ʧ/

The 'ch sound' /ʧ/ is unvoiced (the vocal cords do not vibrate during its production), and is the counterpart to the voiced 'j sound' /ʤ/.

To create the /ʧ/, air is briefly prevented from leaving the vocal tract when the tip of the tongue presses against the back tooth ridge while the sides of the tongue press against the upper side teeth. The sound is aspirated when the air is released with friction (similar to the friction of an sh sound).

Many English language learning pronunciation students often find it helpful to think of the /ʧ/ as stopping the air similar to a 't sound' (but with the tongue a bit further back on the tooth ridge), and then releasing it with the friction of an 'sh sound' /ʃ/.