How do I know if I have noise-induced hearing loss?

The telltale sign of NIHL is speech sounding distorted and less clear—but not necessarily softer. You can still hear people talking to you, but it’s harder to make out all the exact words.

Answer Extra: 

The most sensitive part of the eardrum is the region that detects high-frequency sounds. So whether hazardous noise is low-frequency (a foghorn) or high-frequency (static), a high-frequency hearing loss—where speech occurs—is the result.

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source: We Choose to Hear - And Listen