Hearing aids do not restore normal hearing- they "aid" your ability to hear.
Hearing aids do not "take over" your hearing. In fact, today's devices do not amplify everything equally. Today's technology permits the audiologist to selectively amplify only what you need. For example, if you hear low pitched sounds normally, they are not programmed to be amplified.
Loudness growth is not linear. This means that soft and average sounds may be increased but loud sounds are not.
Soft sounds should be audible
Speech should be clear in difficult listening environments.