Just in case any of you tech heads are up with this, or can google better than us.
My brother has zero hearing, and has trouble limiting the loudness of his voice. He has a device he can use with his computer, to indicate the decibel level with coloured bars. There are also ones for industrial usage.
Something along these lines, but he's after one he can wear on his wrist for conversation anywhere.
http://handsun.en.made-in-china.com/product/wqKnTOHGXaYv/China-Sound-Level-Indicator-Personal-Noise-Meter-SL-601-.html
Thanks for any thoughts.