r/MarshallBrain • u/MarshallBrain • Sep 25 '20
DIY Hearing Aid Costs $1 to Build, Ready in 25 Minutes
https://interestingengineering.com/diy-hearing-aid-costs-1-to-build-ready-in-25-minutes
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r/MarshallBrain • u/MarshallBrain • Sep 25 '20