sh sound /ʃ/
How to pronounce the sh sound
The sh sound is unvoiced (the vocal cords do not vibrate during its production), and is the counterpart to the voiced zh sound.
To create the sh sound, air is forced between a wide groove in the center of the front of the tongue and the back of the tooth ridge. The sides of the blade of the tongue may touch the side teeth. The lips are kept slightly tense, and may protrude somewhat during the production of the sound.
This sound is a continuous consonant, meaning that it should be capable of being produced for a few seconds with even and smooth pronunciation for the entire duration.
Common sh sound spellings
 ch spelling
The ch sound (not the sh sound), is the most common pronunciation for the ch spelling.
The sh sound in suffixes
: -tion suffix
The -tion suffix is only likely to be pronounced with a ch sound when it is preceded by an s sound (as in the words question and suggestion). In most other circumstances, the sh sound is the more likely pronunciation for this suffix.
: -sion suffix
The -sion suffix is only likely to be pronounced with a zh sound when it is preceded by an r sound or a vowel sound (as in the words version and vision). In most other circumstances, the sh sound is the more likely pronunciation for this suffix.
The sh sound before suffixes
The -ure suffix and -ious suffixes do not contain an sh sound within them. However, when these suffixes are preceded by the letters s, c, or t, those letters may be pronounced as an sh sound.
: s+ure spelling
In the s+ure spelling, the letter s is usually only pronounced as the sh sound when it is preceded by a consonant sound or is spelled with two adjacent letter s's. If the s+ure spelling is preceded by a vowel sound, the word is likely pronounced with a zh sound (as in the word closure).