High frequency hearing loss
High frequency hearing loss is experienced by one in two people over the age of 50. It happens when the delicate nerves (hair cells) in the inner ear break down and lose their ability to convert sound vibrations into the electrical signals needed by the auditory nerve. The auditory nerve itself can also become damaged, preventing sound signals from reaching the brain.
This type of hearing loss is a natural part of the aging process, but it can also be caused by over exposure to loud noise or loud music. People with high frequency loss have difficulty hearing softer, high-pitched sounds (like "s", "t" and "f"), but no difficulty hearing the deeper vowel sounds. In quiet listening situations they can follow a conversation, but when it gets noisy, they need amplification in order to hear clearly.
Broadband hearing loss
People with broadband hearing losses can have just as much difficulty hearing low tones as they do the high tones. This makes following a conversation very hard because they can't hear the vowels and consonants that help us to distinguish between one word and another. They need more clarity AND more volume in order to hear better.