51动漫

Hearing aids pick up airborne acoustic signals, and can be switched to receive signals from an induction loop. Why haven鈥檛 they been designed to receive TV and radio signals directly?

Adrian Smith, Headingley, West Yorkshire, UK

We pay 拢25 for every answer published in 51动漫. To answer this question 鈥� or ask a new one 鈥� visit newscientist.com/lastword. Terms and conditions apply.

This article appeared in print under the headline 鈥淓ars tuned鈥�