The tape recorder will record either nothing or a very faint sound. Now, place the metronome right at the opening of the first tube. The resulting recording should be quite clear. This activity demonstrates that sound waves in air will bounce off a flat, solid surface, like a ball bouncing off a wall. If, however, the sound waves are bounced off a surface that is soft or bumpy, the waves will break up or fade away.
Volume is measured in decibels.
Amplifying and recording sound. Take a piece of plastic tubing that fits tightly over the narrow ends of 2 funnels. Attach a funnel to each end. This activity demonstrates how some devices can amplify sound. They sing a song together in the microphone, hooked to the tape recorder.