Hands-on Activity Sounds All Around

Learning Objectives

After this activity, students should be able to:

• Describe the basic concept of a hearing-aid and how sound can be amplified.
• Describe the need for the modern-day hearing aid and how engineers have improved the device with new materials and technologies.
• Describe the differences between background and foreground noises, and high-pitch and low-pitch sounds.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

For the introductory demonstration, the teacher needs:

• ear trumpet images to show students (either print out pictures or overhead transparencies, or view website images; recommend sources: Hearing Aid Museum website at http://www.hearingaidmuseum.com/gallery.htm or Phisick's Antique Ear Trumpet Gallery available through the Deafness and Hearing website:http://phisick.com/item/rein-silver-plated-grand-opera-dome-ear-trumpet/ )
• overhead projector
• clear tub of water and various sized pebbles or marbles, to demonstrate wave propagation

Each group needs:

• scissors
• masking tape, 20 cm
• cotton balls, 2 large
• office or construction paper, 4 sheets
• blindfold
• Shhh... Do You Hear That? Worksheet, one per person
• Sounds All Around Design & Evaluation Worksheet, one per person

For the entire class to share:

• roll of paper towels
• assorted raw materials from which teams can design their own ear trumpets, such as plastic soda bottles, disposable cups, cardboard tubes, tubing and plastic sheets, as described next
• 6-8 plastic soda bottles with the bottoms cut off; get the 360 ml (12 oz) size
• 6-8 each, cups made of Styrofoam, plastic and paper; get the 180-240 ml (6-8 oz) size
• 6-8 cardboard tubes from paper towel or toilet paper rolls
• 4-6 segments clear rubber tubing, 0.7 cm inner diameter, 50-80 cm length
• 4-6 segments plastic tubing, 1.5 cm inner diameter, 10-15 cm length
• 4-6 pliable plastic sheets, 15 cm x 12 cm, available at craft stores; alternatively, use blank overhead transparency sheets
• (optional) 4 funnels of various sizes; plastic works best

Worksheets and Attachments

Pre-Req Knowledge

Students should have an understanding of high and low pitch as well as amplitude (different levels of loudness); an understanding of decibels is not necessary. Students should also have an understanding of the parts of the ear, including the pinna and the ear canal, and the concept of a sound wave.

Introduction/Motivation

(Demonstration: Have on hand images of ear trumpets, an overhead projector, and a clear tub of water and various sized pebbles or marbles. See Materials List for recommended website sources for ear trumpet images.)

Do you know anyone who has trouble hearing? I know a boy who lost his hearing because he developed an ear infection. Has anyone here had an ear infection before? Lucky for this boy, his hearing loss was not permanent. Once the ear infection went away, all of his hearing returned to normal. But, during the time when he lost his hearing, he had a very rough time — peoples' voices were muffled, and he could not hear the phone, the microwave buzzer, or the school bell. What do you think would have helped him solve this problem at the time? (A temporary hearing aid!)

Have you ever cupped your hand around your ear so you can hear better? Try it! Do things seem louder? Why do you think this is? (Get students to think about the shape; your cupped hand acts to "catch" more of the sound.) Great! A few centuries ago, people used ear horns or ear trumpets to help them hear. Take a look at some of these funny-looking contraptions. (Show students images of ear trumpets.) Some of these were even considered fashion accessories! Why do you think they are shaped the way they are? (Just like our hands, the cone shape helps funnel the sound into the ear canal.) Remember that sound is a wave and sound waves move away from the source in all directions, just like these waves do when I drop an object into the water. (Show this to students by dropping a pebble into a clear tub of water placed on an overhead projector.) For sound though, we cannot see the wave — but we hear it instead.

In today's activity, we are going to explore how ear trumpets work. We will follow the engineering design process to design, build and test our own ear trumpets! Can anyone remember the seven basic steps to the engineering design process? (Ask, Research, Imagine, Plan, Create, Test, and Improve.) Great! Before we get started, let's explore all the sounds around us. Many sounds go unnoticed — these are considered background noises — while others seem to stand out, like my voice or the sounds of music. Let's start today by being very quiet and listening to the sounds around us. (Hand out the Shhh... Do You Hear That?" Worksheet and begin the activity.)

Procedure

Background

In historic times, ear trumpets (also known as ear horns) were made from hollowed-out horns from cows, rams or other animals. In later centuries, engineers experimented with different materials such as silver, brass, ocean shells, and more recently, plastic. To aid in his deafness, composer and pianist Ludwig van Beethoven used many of these devices, which in the 1700s and 1800s, were considered a fashion accessory. Today, the ear horn has been replaced with the modern hearing aid, typically worn in the outer ear.

To achieve the highest quality of amplified sound, engineers experimented with different materials and shapes for ear trumpets over the years. Amplitude measures how much energy a particular wave carries. For humans, amplitude is interpreted as loudness or intensity. A material's ability to transmit sound depends on its properties. For example, stiff plastics and rubber tubing transmit sound energy well, while cloth and porous foam absorb sound energy. In addition, the more layers through which sound waves must travel, the more energy that is absorbed and the quieter the sound seems.

Sound travels at different speeds through different materials, or mediums. The speed of sound depends on the stiffness of the medium (measured by a quantity know as the bulk modulus), as well as its density. Sound travels faster in solids than in gases, and faster in less dense mediums than in denser ones. For example, sound travels faster through a metal rod than it does through air, and faster through hydrogen than oxygen due to hydrogen's lower density.

For more information on the many different designs of modern-day hearing aids, see the associated My Mechanical Ear Can Hear! lesson.

Before the Activity

• To introduce the activity, show students ear trumpet images and demonstrate wave propagation by dropping a pebble into a clear tub of water placed on an overhead projector. Recommended sources for images: Hearing Aid Museum: http://www.hearingaidmuseum.com/gallery.htm and Antique Ear Trumpet Gallery: http://phisick.com/item/rein-silver-plated-grand-opera-dome-ear-trumpet/
• Gather materials and make copies of the Shhh... Do You Hear That? Worksheet, and the Sounds All Around Design & Evaluation Worksheet, one each per person.

With the Students

1. Have students begin by sitting quietly at their desks, filling out the first worksheet (Shhh...), which is intended to help them identify background noises that often go unnoticed. Allow one minute for students to quietly list all the sounds they hear. No talking allowed. Afterwards, ask students what they heard, the pitches of the different sounds and their relative intensities; this helps to clarify the definitions of pitch and amplitude (or loudness).
2. Ask the class to define the problem at hand. Then reiterate by stating the project goal: "Your goal is to engineer an ear trumpet that helps you hear clear, amplified sound when one of your ears is blocked."
3. Have students think of various sounds they can create that have different pitches and amplitudes. (Examples: Zipping up a backpack, snapping fingers, shuffling paper, knocking on a desk, tapping a rubber tub with an eraser, slicing scissors, playing a stereo or musical instrument. Make sure to also include voices.) As a class, for the activity, agree to use 6-8 different sounds that include a good mix of high and low pitches that can be reproduced with the same amplitude each time. Together, categorize these sounds as high pitch or low pitch, On their worksheets, have students and rank the sounds, a-i, according to their amplitudes (a being the most quiet [softest] and i being the loudest).
4. Divide the class into groups of two students each. Have one person be the "listener" and the other the "observer." Have the "observers" stand in a large circle around the room while the "listeners" stand in the middle with cotton in one ear and blindfolds on. The blindfold helps the cotton stay in place and disguises the direction from which the sound originates.
5. Assign the "observers" each one of the pre-determined sounds to make while the "listeners" identify the sound by pointing in the direction from which they heard that sound. (Make this a quiet activity; talking is distracting and unnecessary.) Continue through the a-i list of sounds.
6. Once all the list of sounds have been made, have students fill out Part 1 of the second worksheet, either the "For the listener" or the "For the observer" sections, first writing down the list of sounds, a-i, circling H or L for the pitch of each sound. For this step, the listeners should be evaluating how well they can hear the sounds, while the observers should be watching their partners to see if they can identify the sounds and the directions from which they came. This step provides students with a baseline to which they can compare their ear trumpet design later. Repeat this step again with the listeners and observers switched, so each student has the opportunity to experience the baseline case.
7. Next, have students follow the steps of the engineering design process to engineer their hearing aid devices (ear trumpets):

• Ask: Identify the needs and constraints of making the ear trumpet. 
• Imagine: Introduce the materials available for creating ear trumpets. Give the groups time to think up ideas. (Alternative material distribution idea: Set material prices and give students a maximum budget to spend for each ear trumpet design.)
• Plan: Under the "Plan It!" section of the worksheets, have students draw their agreed-upon team designs and label the materials used for each component of the designs.
• Create: Once designs are teacher-approved, direct student teams to build.
• Test: Once all groups have a device to test, perform steps 4-6 again, using the same sounds as before, and completing the Test It! portion of the worksheets. This enables students to evaluate their designs by ranking how well their devices aided in hearing differently-pitched sounds and voices, and how big of an "ocean-effect" the devices caused, which is considered a design flaw and should be minimized. 
• Improve: If time allows, have students make modifications to their original designs. Retest the second design, following steps 4-6 again, recording results on the Improve It! portion of the worksheet. Make sure students recognize their original design flaws and which adjustments improved their ability to hear.

8. Conclude the activity with a class discussion using questions provided in the Assessment section. Ask teams how well their ear trumpets helped them hear and if they could recognize the direction of the sounds more accurately. Have them refer to their evaluations (testing data) as part of the discussion.
9. (optional or assign as homework) Have students complete the Conclusion questions on the last page of their worksheets.

Vocabulary/Definitions

amplify: To increase the loudness of a sound.

biomedical engineer: A person who blends traditional engineering techniques with the biological sciences and medicine to improve the quality of human health and life. Biomedical engineers design artificial body parts, medical devices, diagnostic tools, and medical treatment methods.

ear trumpet (ear horn): A passive, funnel shaped device used to gather sound energy in the form of waves, and direct them into the ear canal.

hearing aid: A biomedical device used to assist hearing, consisting of a microphone, an amplifier and a circuit.

pitch: The property of a sound measured by its perceived frequency.

Assessment

Pre-Activity Assessment

First Worksheet: Have students record their observations on the Shhh... Did You Hear That? Worksheet, which asks them to listen quietly and describe the sounds around them as either soft or loud, low-pitched or high-pitched. Review their answers to gauge their mastery of the subject.

Activity Embedded Assessment

Second Worksheet: Have students follow the engineering design process steps, and document designs and testing results using the Sounds All Around Design & Evaluation Worksheet. After students have finished their worksheets, have them compare answers in a class discussion.

Post-Activity Assessment

Class Discussion: To conclude, ask the groups how well their ear trumpets helped them hear and whether they could recognize the direction of the sounds more accurately when using them. Have them refer to their worksheet evaluations to compare testing results. Ask the students:

• What shapes worked best? What materials worked best?
• If you had permanent hearing loss, would your ear trumpet be a practical device?
• What makes your ear trumpet difficult to use?
• What properties would an ideal hearing aid device have?

Safety Issues

• Warn students of the dangers of putting sharp or small objects into their ears.
• Students should not walk around the classroom with blindfolds on.

Troubleshooting Tips

Have some Q-Tips on hand for cleaning ears.

Activity Extensions

Introduce students to more information on musical sound and frequency with the TeachEngineering Making Music lesson.

Activity Scaling

• For lower grades, have students choose and rank pitches for four sounds instead of six.
• For higher grades, have students keep track of the cost of materials used to make hearing aid devices.

Additional Multimedia Support

For good photographs and information on ear trumpets and hearing-aids, see the Hearing Center Online's Ear Wax Museum: A History of Making Your Hearing Better website at: http://www.hearingcenteronline.com/museum.shtml

For additional photographs and information on ear trumpets, see the Phisick's Antique Ear Trumpet Gallery, available through the Deafness and Hearing website at: http://www.deafness-and-hearingaids.net/2007/12/04/antique-ear trumpets/

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.