so i have just diagnosed SD with noise induced bilateral high frequency sensorineural hearing loss. no surgical interventions are possible with this, but you could probably benefit from amplification if you deemed your situation bad enough to warrant it. the reason you are struggling, is that human speech is complex and primarily made up with sounds between 500-5000Hz. with your high frequency loss, you are missing out on information that allows you to hear and tell the difference between soft high frequency parts of speech like t, k, f, s, sh and ch thus making it sound like people are mumbling when in fact they are not. NEXT!