Student Guide

Talking Tapes

Experimenting with volume of sound.

How does the speed of vibration affect sound?

This resource was originally published in PhysicsQuest 2017: Sound.

How does the speed of vibration affect sound?

Intro

Before the experiment

How do sounds sound
How do sounds sound different in an empty room vs. a space full of stuff?
- A carpeted room vs. one with tile or wood?

Setting up

Put the self-inflating balloon
Put the self-inflating balloon on a flat table and lean on it until the packet in the middle pops. This will start a chemical reaction that will inflate the balloon. It may take a few minutes to inflate. Shake the balloon a bit to make sure the chemicals are mixing well.
Find the notched end
Find the notched end of the red “talking tape”.
Cut a small square
Cut a small square out of the top of the PhysicsQuest box and a small hole in the other side.
Cut a small hole
Cut a small hole in the bottom of the paper cup.

During the experiment

Collecting data

Poke a small hole
Poke a small hole in the bottom of the paper cup.
Thread the notched end
Thread the notched end of the talking tape through the hole and know it so it stays inside the cup.
Put the cup
Put the cup up to your ear.
Run your thumbnail
Run your thumbnail down the strip.
What do you hear?
What do you hear?
Now run your thumb
Now run your thumb down it very slowly. How does the sound change?
Now run your thumb quickly
Now run your thumb down it very quickly. How does the sound change?
What is the talking
What is the talking tape “saying”?

Run your thumb
Run your thumb down the talking tape at a speed that lets you hear what the tape is saying.
- What’s the best way to hear the sound?
Now hold the notched end
Now hold the notched end of the tape in the PhysicsQuest box and run your thumb down it.
- What do you hear?
- How does it compare?
Do this again
Do this again with your ear next to the hole you cut in the box.
- How did the sound different?
Repeat step 2
Repeat step 2 with the tape held against the book.
- What do you hear?
- How does it compare?
Put your ear
Put your ear next to the balloon opposite the tape and pull your thumbnail down the tape.
- What do you hear?
- How does it compare to the sound you heard when your ear wasn’t next to the balloon?
Repeat step 6
Repeat step 6 with your ear on the top of the balloon.
- What do you hear?
- How does it compare to the sound you heard when your ear was on the side of the balloon?

Analyzing data

How did the pitch change
How did the pitch change when you changed the speed of your thumbnail?
How did the speed
How did the speed of vibration change when you moved it faster or slower?
Why do you think
Why do you think the pitch changed the way it did?

Rank the items
Rank the items used in this activity from loudest to softest.
____Cup
____Cup with ear next to it
____Box
____Box with ear next to hole
____Book
____Balloon with ear on side
____Balloon with ear on top
What do all
What do all the loudest things have in common?
What do you think
What do you think is happening to the sound waves in the object when the talking tape is pulled?
Why do you think
Why do you think the hollow things sound louder?
Why do you think having
Why do you think having your ear next to the cup (vs not near the cup) made the sound louder?

Conclusion