aid
hearing aid

gain
to gain a hearing

hard
hard of hearing

hardness
hardness of hearing

hear from
I look forward to hearing from you

hearing
hearing loss

impairment
hearing impairment

keen
to have a keen sense of hearing

look forward to
looking forward to hearing from you

preliminary
preliminary hearing

sense
...sense of hearing / the sense of smell / the sense of taste / the sense of touch

upon
upon hearing this

within
within hearing