Hands-On-Physics: SOUND - Extension #5
	HELP FOR THE VISUALLY IMPAIRED

Can you build a useful device for visually-impaired persons? This is an invitation to invention. Below, I describe how to make an audible light meter. However, it would be much more exciting if your imagination leads you to a completely new idea that you decide to try. Take some time to think about it.

INTRODUCTION

An audible light meter produces a tone which varies as the intensity of light on its sensor changes? You might ask the following question, "Why would a visually-impaired person be interested in a light meter?" Being a teacher, I like to answer questions with questions. "Why would a person with average vision be interested in measuring microwave, infrared, or ultraviolet radiation? The human eye is not sensitive to radiation in these portions of the electromagnetic." After you have had a chance to consider this, return to the original question.

This extension involves the conversion of light into sound. One way to build a Audio Light Meter is to alter the Tone Generator you made for the Core Project.

EXPERIMENT

0. What is the maximum, minimum, and minimum change in light intensity that you can detect?
1. How far apart must two light bulbs be before the light meter can recognize them as separate objects?
2. Blindfolded in a room, what features can you recognize using the audible light meter as a probe?
3. How can the audible light meter be converted into a more useful device?