Lesson Sound Environment Shapers

Learning Objectives

After this lesson, students should be able to:

• Describe the role of an acoustical engineer.
• List several common designed or "natural" acoustic features of a building.
• Make an observation that sound travels as wave energy.
• Use the science of sound waves to explain how designed sound environments work.

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

Worksheets and Attachments

Pre-Req Knowledge

Students should understand that sound travels in waves and has a direction of travel. This lesson is ideal to accompany a science unit on sound or waves.

Introduction/Motivation

Can you imagine an office located next to loud city streets? Or, a classroom next to a gymnasium full of running students? Well, acoustical engineers sure can! In fact, part of the job of an acoustical engineer includes designing places for people to escape the loud noises of everyday life. Acoustical engineers design quiet sound environments, as well as sound environments for spaces that are supposed to be loud with sounds (auditoriums, concert halls and sports arenas, among others). They even design the sound barriers (walls) that you often see between a noisy highway and a quiet neighborhood (see Figure 2). These walls are part of noise mitigation efforts — simply referred to as noise control.

What kind of sound environment is a movie theater? (Answer: Quiet.) How about this classroom? Everyone be quiet for a few moments and listen. What do you hear? (Answer: Students may hear different things, such as feet shuffling or coughing, but overall it is [hopefully] quiet. Or, perhaps other sounds can be heard from nearby classrooms, the gym or parking lot.) How about a downtown street? (Answer: Loud.) Why do you suppose these different sound environments exist? People want a quiet environment to watch movies and conduct classes, but quiet is not important on a busy city street (unless you live next to it!). So people decide where quiet environments are important. How does this relate to acoustical engineers? What do they know how to do? (Answer: Acoustical engineers know how to create quiet spaces for people to enjoy.)

How do acoustical engineers create quiet spaces? To answer this question, think about what you have been learning (or already learned) in science class. Now, with a partner next to you, pull out a piece of paper and roll it up into a long tube. Whisper something to your partner through the tube. Did the sound travel? (Answer: Yes). Where did it travel from and where did it travel to? (Answer: From one partners mouth to the other partners ear). How does sound travel? (Answer: Sound travels in waves.) Waves are a form of energy transfer. Energy is transferred by way of waves in water, ground (earthquake/seismic waves), and by sound!

Let's compare a movie theater to a gymnasium. When a film is running, do you hear echoes? (Answer: No.) When you yell in a gymnasium, do you hear an echo? (Answer: Yes, usually.) What do you think explains this difference? How is the inside of a movie theater different from the inside of a gymnasium? (Answer: Theaters have thick, soft curtains, fabric-covered walls, angled/curved walls, and carpeting, while gyms usually have only hard surfaces [floors, windows, walls].) So what do engineers do to make the theater quiet inside? (Answer: They design the room with soft surfaces, such as curtains, fabrics, carpets and other materials that absorb sound instead of reflecting it. They may also make sure to muffle the sound from the film projector, heating/cooling system and doors, so they are not distracting to viewers.) So, to create quiet sound environment, acoustical engineers consider the reflection and absorption of sound waves. After the lesson students can act as acoustical engineers with the associated activity Form vs. Function where they analyze the sound performance of different materials that represent wallpaper, thick curtains and sound-absorbing panels.

Lesson Background and Concepts for Teachers

Acoustical engineers study the properties of sound and vibration in order to create controlled sound environments for people. Even though it is a specialized field, many acoustical engineering firms exist around the country and world. These engineers design sound walls to surround highways, barriers to alleviate the loud noise of airplanes and trains, and even super-quiet dishwashing machines. But, the most common work for acoustical engineering is in building design to reduce unwanted sounds (such as noise control in work places, homes, schools, theaters, auditoriums, sports arenas, airports, industry and road systems) and make useful sounds (such as for medical ultrasound equipment, sonar, and music and voice reproduction).

Architects seek consulting from acoustical engineers as they design spaces for a better sound environment. The sound environment, or acoustics, can be a major influence on whether or not the space as a whole is pleasant. Each building poses a unique challenge. Acoustical engineers provide solutions that not only create good acoustics but fit in with the overall architectural vision of the space.

The acoustical engineers at Arup, an international engineering firm, created a sound lab in which they can simulate sound environments. To test their designs in the sound lab, they can listen to artificial performers in a concert hall, for example, before it is even built. This technology is made possible through the understanding of sound waves.

Associated Activities

• Form vs. Function - Students analyze the sound performance of different materials that represent wallpaper, thick curtains and sound-absorbing panels. They use what they learn to model and design the sound environment for a room.

Lesson Closure

Today, we learned about many different sound environments. Acoustical engineers shape these environments to meet the needs of the people using the spaces. They design various features of buildings to absorb more — or less — sound and to reflect the sounds in desired directions. In addition, they design areas that prevent loud street sounds from affecting buildings and homes.

To make their designs, acoustical engineers first learn how sound travels (in science classes, just like you). What happens to sound waves when they hit hard surfaces? (Answer: The sound waves are reflected, so the sound continues.) How about when sound waves strikes a soft surface? (Answer: Sound waves are absorbed by soft surfaces, so the sound does not continue.) Acoustical engineers use this information when designing sound environments to both enhance sound quality and reduce loud noises. (Show students the attached Example Acoustics Strategies in a University Classroom Building for more real-life examples.)

Vocabulary/Definitions

acoustics: The study of sound; the characteristics of sound in an environment.

echo: A repetition of sound produced by the reflection of sound waves from a wall, mountain, or other obstructing surface.

Assessment

Pre-Lesson Assessment

Discussion Question: Solicit, integrate and summarize student responses to the question below. After listening to their answers, tell students that they will learn the correct answers during the lesson.

• Do you think building designers design some buildings to be quieter than others? Why would they do that? Give me some examples.

Post-Introduction Assessment

Diagramming Sound Movement: Draw Figure 3 on the board. Be sure to re-create the figure accurately (i.e. ensure that the sound waves always bounce at the same angle they hit the wall at. You could even measure the angles using a large protractor so that students can see that they are the same). Tell students that the arcs in the diagrams represent both source and reflecting sound waves in a room. Ask them to determine which room is most likely the gymnasium and which is a movie theater. (Answer: The gymnasium is the room on the left. The movie theater is the diagram on the right—the one with fewer reflecting "sound waves.")

Discuss with the students how angles are formed from both rooms (stress again to students that the sound waves should always bounce at the same angle they hit the wall at). Remind students that angles are geometric shapes that are formed wherever two rays share a common endpoint. Have students identify these common endpoints.

Lesson Summary Assessment

Look and Discuss: Ask students to discuss the following questions with a partner, then discuss as a class. (optional) Show students the attached Example Acoustics Strategies in a College Classroom Building for more real-life examples.

• Did the engineers and architects who designed our classroom care about the sound environment? How can we tell? What is one piece of evidence that shows acoustical engineering? (Possible answers: Sound-absorbing ceiling tiles, carpeting, thick walls, door jamb padding, placement away from noisy gym/playground/mechanical room/roads, reading nook away from main classroom space.)
• How could we make improvements to the sound environment of our room? (Possible answer: Create a reading corner with soft furniture, curtains and an area rug.)

Lesson Extension Activities

How does distance affect how sound travels? Have students think about designing a building that uses distance to quiet the sound environment. For example, if you were designing a school, where would you locate the various rooms to best take advantage of distance for purposes of improving the sound environment? (For example, not placing the gym or cafeteria next to the library.) Assign students to sketch a floor plan re-arrangement of the main spaces in their own school and explain the logic behind their suggested improvements.

Assign students to research high tech sound baffles or other devices and materials designed to reduce sound. In what situations might sound baffles be used? From what materials are sound baffles made? How do their designs absorb sound better than standard ceiling, wall and floor materials?

Can excess noise affect our health? Have students research the health effects of noise. Specifically, have them find out if noise contributes to hearing loss, blood pressure problems or sleep disturbances.

References

Copyright

Contributors

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Acknowledgements

The contents of these digital library curricula were developed by the Integrated Teaching and Learning Program under National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.