From what I understand is that some hearing loss is actually a loss of certain frequencies so you won’t hear things in that frequency anymore. Using a hearing aid that just increases the volume may work but may also damage your hearing farther. What I was told was that is why you need a doctor and a prescription because they determine what frequency is missing and they don’t make the sounds louder but alter the frequencies you don’t hear well into a frequency you do hear. With that said I have also heard there are apps that could easily determine what you would need for frequency adjustments without the need for a doctor. I think these apps with paired over the counter hearing aids would be the best situation.