B is an earlier developing sound. Typically, children master B by 3 years of age.
Below is a brief explanation on what all the articulators (tongue, lips, teeth, jaw, breath, voice) must do to say /b/correctly.
Lips: Lips must be slightly pressed together (enough not to let air escape but not too much where it feels unnatural).
Tongue: Nothing. It is relaxed in a neutral position.
Teeth: Nothing. They are relaxed in a resting position.
Jaw: The jaw is up and centered.
Breath: /B/ is a plosive sound which means air bursts out of the mouth upon sound production.
Voice: /B/ is a voiced sound so our voice box is turned on.
Say /b/ in front of a mirror and look and feel what each muscle is doing to say the sound correctly.
Please say B in front of a mirror and look and feel what all your muscles are doing. Once you have a good handle on how to say B, you can now better teach your child.
Speech therapists use a variety of cues during therapy including tactile (touch), verbal (words), and visual (visual models/mirrors) to elicit a correct sound production. Below are the most useful cues for /b/.
For visual cues to work, make sure your child is looking at you. You can bring objects near to or point to your mouth to help guide his/her attention.