Occasional Inability To Hear Low Frequency Sounds. Tests Done. Medicine Taken. No Relief. Treatment?

I am a lecturer by Profession and age of 53. While talking with others ,, i am able to hear without any burden in the house as well as in other places.. but when they reduce the voice very less i have problem in heraring. and feel embrassing when I ask them to repeat. but my concerns is here as below.. particularly with students ,, I could not ask them repeat to avoid embrassing and I used to go near to them to understand what they ask . it happens sometime only. it is also noted that in the class room , structure makes generates echo not clear the messages .. building also contributs this communication jamming/ disturbances. went for testing.. Doctor gave me one tablets for one week. and also ear drops.. not improved.. I want to stop further damage of my ear hearing . i am sure some problem in my ar as well as class room/bulding.. i can not repair the building.. but want to ensure i am and my hearing is ok. or improve to be ok. thanks.