i have sat and watched them test my child. She hears at 15 db, that is audiologically considering hearing in the "normal range".
dB and frequency are two different things. You do know this, don't you?
She has also had discrim testing that clearly shows her discriminating all the sounds of speech.
There's a disconnect between what you think you're seeing and what you're really seeing. When a CI is in place, the eardrum is still responding to whatever sound wave is hitting it. That's simple physics. However, a person with CI is typically not able to distinguish between closely grouped frequencies because the CI processes them as a single frequency. To put it another way, it is taking the entire range of frequencies and presenting them as a limited number of frequencies (typically 24 in a modern CI).
So while you could say, in theory, that a CI user has access to to the full range of speech sounds, this does not give an accurate picture of what they're actually hearing.
Does that make sense?