Do you have any ideas for low cost ways to help people with little or no hearing to enjoy a music concert?

Quoting from Working for the Sensory Trust

“We’ve found that someone profoundly deaf can hold a balloon and feel the vibration of the music – it happened to a friend of mine, who recognised the song. So I want to end with a question – are there other ways we can help people with hearing problems to enjoy music and sound? Your cheap and cheerful solutions would be much appreciated!”