My mother was hard of hearing. She spent $200 each ear for hearing aids. Then she spent $600 each ear for better model hearing aids. 1985 dollars. I suggested using ordinary plastic kitchen funnels as ear trumpets. No batteries to replace. No squealing when the volume control was set too high. Good frequency response over speech frequencies. My mother was too self-conscious to use funnels. Many people in the world live on $2 per day. They cannot afford hearing aids or the luxury of being self-conscious. There is need for an ear trumpet that is self-supporting on the ear, so the wearer does not have to dedicate a hand to holding the trumpet in place.