Native speakers of English often don't use voicing to differentiate between /b/ and /p/. Not only these sounds, but all plosive sounds - t, d, k, g. Rather, aspiration is more notable than voicing. Aspiration is the air that is released between the sound /p/ and the next sound (in English, this will be a voiced sound). In a voiceless sound (p, t, k) there will be a lot of air released in this time. In voiced soinds (b, d, g) there will be much less air released in this time.
So, to perhaps suggest a strategy to get your /b/ to be more like /p/, release more air when it is p. Especially when the sound is at the beginning of a word before a vowel. If you put your hand in front of your mouth, you should feel a burst of air with a word like "pin" more stronger than a burst of air with a contrasting word like "bin". It is this puff of air that native speakers rely on to differentiate between /p/ and /b/.
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