Hearing Aid Kit

TEAK
Hearing Aid Kit / 1

TEAK

Sound and Music

Hearing Aid Kit

Instructor Preparation Guide

Important Terms

Wave

A wave is a disturbance or vibration that travels through space. The waves move through the air, or another material, until a sensor detects the vibrations. For example, your eardrum vibrates from sound waves to allow you to sense them.

Medium

A medium is a substance or matter which a wave travels through. Examples of a medium include: water in the ocean, the air in a stadium at a concert, or the skin of a drum head.

Sound

Sound is a mechanical vibration that travels through matter as a compression waveform. Although it is commonly associated with moving through air, sound will readily travel through many other materials, such as water and metals. Because sound is the vibration of matter, it does not travel through a vacuum or in outer space. Also, there are certain insulating materials that absorb sound waves, preventing the waves from penetrating the material.

Waveform

A waveform refers to a graphical representation of sound, where the pressure is plotted on the vertical axis and time is plotted on the horizontal axis. This plot is the time domain representation of an audio signal.

Amplitude

Amplitude refers to the magnitude of a wave. In the case of a sound wave, it would be the maximum pressure that occurs at a point the wave travels through. The greater the amplitude of a wave, the greater the intensity of the sound will be.

Frequency

Frequency means the number of times something occurs within a given time period. Frequency for waves is usually measured per second. The unit for frequency is Hertz (Hz), which means per second. So, a wave frequency of one Hz means that one wave occurs per second. High-pitched sounds are high-frequency; low-pitched sounds are low-frequency.

Pitch

Pitchrefers to how high or low a sound seems depending on its frequency. The shorter the wavelength, the higher the frequency becomes, and the higher the pitch that we hear.

Resonance

Resonance is the tendency of a system to oscillate at larger amplitude at some frequencies than at others. For example, a guitar string plucked by itself makes a weak sound. But when added to the hollow body of the acoustic guitar, the sounds resonate and are amplified.

Sine Wave

A sine wave is a mathematically unique waveform that is slowly varying. It is known as a pure tone.

Square Wave

A square wave is a common waveform that is easy to create electrically. Theoretically it consists of an infinite number of sine waves at odd harmonic intervals.

Resistor

A resistor is an object that prevents the passage of a steady electric current. Resistors have the effect of linearly reducing the amplitude of a signal passing through them.

Capacitor

A capacitor is an electrical component that permits a certain amount of current to pass through it via an electrostatic interaction between two parallel strips of metal. At a certain point the capacitor cannot hold anymore charge, and therefore impedes the flow of current entirely. Thus, it blocks all constant signals and passes higher frequency content more easily. If an output is taken across a capacitor a low-pass filter is created. If an output is taken in series with a capacitor a high-pass filter is created.

Amplifier

An amplifier is a device that changes the amplitude of a wave without changing the waveform shape. What is happening mathematically is the signal is being multiplied by a constant value at every point. Any number multiple is referred to as gain. The process of amplification allows one to adjust the loudness or softness of music.

Filter

A filter is a device that changes the waveform or frequency content of a signal. The filters in the activity are high-pass, and low-pass filters. High-pass suppresses low frequencies, and a low-pass suppresses high frequencies. The orientation of the electronic filters are shown below, low-pass on the left with high-pass on the right.

Gain

Gain is a measure of the ability of a circuit (or amplifier) to increase the power or amplitude of a signal from the input to the output.

Resources

Note: Many of these resources were used in assisting the creation of the following Lesson Plan and we want to thank and reference them for their valuable instruction.

Image Resources

Date: March 30, 2010Time: 1:22AM

Date: March 30, 2010Time:1:22AM

www.gaussmarkov.net

Date: March 30, 2010Time:1:22AM

Date: March 31, 2010Time: 10:51AM

Date: March 31, 2010Time: 11:05AM

Activity Preparation Guide

Overview

The purpose of this kit is to help students understand how sound travels, both mechanically and electrically. After teaching the students the basics about sound waves, they will then participate in a hands-on activity that will help them visualize this concept. They will also get to complete activities that demonstrate how a hearing aid works, and use the engineering design process to optimize their own hearing aid! This kit will teach students about sound, engineering, and the value of teamwork.

Learning Objectives

By the end of this lesson, students should be able to…

Explain what sound is and how sound waves travel
Understand the goal and necessity of amplification
Explain how a hearing aid helps people who are hard of hearing
Understand the engineering design process

Engineering Connection

Engineers use the design process to create a product that will fulfill the needs of a customer. In the case of a hearing aid, it was designed with the purpose of helping people with diminished hearing capacity improve their hearing level. The electrical components that make a hearing aid work must allow for customer input, such as volume adjustment. The engineering design process allows engineers to make decisions regarding the product, and then test the validity of their design. Through this kit, the students will get to see and test the “behind the scenes” things that make a hearing aid work.

ActivityDescriptions

Slinky Sound Waves – 5 Minutes

Teams of students will use a slinky to create transverse and longitudinal waves. This will allow them to visually see the way that waves travel through a medium.

Cup Telephone Activity – 10 Minutes

Teams of students will be given cup telephones with different string materials. They will test the cup telephones to see if sound is transmitted through the different strings, and determine which material works best.

Hearing Aid Activity – 20 Minutes

Teams of students will use Snap Circuits build their own hearing aid. They will be able to test the hearing aid by changing the gain of the amplifier, which will change the volume, and by speaking into the microphone. This will show the students that sound can be transmitted through an electrical circuit. The students will also need to record data, which will be used to prove or disprove their hypothesis.

Engineering Roles

Mechanical Engineer (ME) – Responsible for assembling mechanical components

Electrical Engineer (EE) – Responsible for attaching wires and electrical components

Sound Engineer (SE) – Responsible for speaker assembly and listening for sound changes during testing

Data Engineer (DE) – Responsible for recording data during testing

Test Engineer (TE) – Responsible for turning circuit on/off and talking into the microphone

NYS Standards

NYS Learning Standards:Top of Form

MST / 1 / E / Scientific Inquiry /
Interpret organized observations and measurements, recognizing simple patterns, sequences, and relationships

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MST / 1 / E / Engineering Design /
Discuss how best to test the solution; perform the test under teacher supervision; record and portray results through numerical and graphic means; discuss orally why things worked or did not work; and summarize results in writing, suggesting ways to make the solution better

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NYS Science Standards:

Standard 4: Energy exists in many forms, and when these forms change energy is conserved.

Students:

• Describe the sources and identify the transformations of energy observed in everyday life

• Describe situations that support the principle of conservation of energy

This is evident, for example, when students:

-Design and construct devices to transform/transfer energy.

- Build an electromagnet and investigate the effects of using different types of core materials, varying thicknesses of wire, and different circuit types

Hearing Aid Kit

DURATION

60 Minutes

CONCEPTS

What is Sound

Sound Waves

Mechanical Sound Travel

Electrical Sound Travel

Sound & Sound WavesIntroduction(5 Minutes)

Background Information:

Sound is a mechanical vibration that travels through matter as a compression waveform. Although it is commonly associated with moving through air, sound will readily travel through many other materials, such as water and metals.The sound waves move through the air, or another material, until a sensor detects the vibrations.

Simplified Definitions:

Sound
Sound is the vibration of matter (stuff).
Sound Wave
A sound wave is the movement of air that is caused by stuff vibrating. A person detects sound when their ear drums feel the vibrating air.

Group Discussion:

(Pose the following questions to the group and let discussion flow naturally… try to give positive feedback to each child that contributes to the conversation)

Has anyone heard sound before? What types of sound have you heard?

Most/all students should answer YES
Loud, soft, phone ringing, talking, doorbell, etc…

Has anyone seen a sound wave before?

All students should answer NO

Learning Objectives

By the end of this exercise, students should be able to…

See how sound waves travel
Describe the two types of sound waves

Materials

Each group needs:

(1) Slinky

Procedure

Read the instructions to the students step by step. Have students raise their hands after they complete a step so the instructor knows to move on.

Give each group of students a slinky
Have the students lay the slinky on a table or non-carpeted floor
Have 2 students (one on each end) hold the slinky so that it is stretched out
Demonstrate how to make a transverse wave and explain that the waves move “up & down”
Have each group make a transverse wave
Demonstrate how to make a longitudinal wave and explain that the waves move “back & forth”
Have each group make a longitudinal wave
Students can change positions (slinky holder vs. wave maker)and re-make the wavesif there is time

Sound & Engineering Introduction (5 Minutes)

Background Information:

Engineers need to understand how sound travels in order to create products that can make sound (like a speaker) and products that pick up sound (like a microphone). In order to transmit sound, engineers can use either mechanical or electrical methods. While each method has its positives and negatives, they are both vital in the engineering of sound transmission.

Simplified Definitions:

**May be helpful to show/draw pictures when explaining these concepts**

Engineering
A technical profession that applies skills in math, science, technology, material, and electronics in order to design and create new products
Amplitude
Amplitude is the height of the sound wave. A higher amplitude means that we hear a louder sound.
Gain
Gain is an increase of the amplitude of a signal from the input to the output.
Resistor
A resistor is an electrical object that only lets a certain amount of electricity though it. A big resistor means a small amplitude (and quieter sound).

Group Discussion:

(Pose the following questions to the group and let discussion flow naturally… try to give positive feedback to each child that contributes to the conversation)

Why do you think knowing about amplitude is important when designing a hearing aid?

The person using the hearing aid needs to be able to control the volume of it.
The engineers need to know how loud the hearing aid can get so they can make sure it stays at a safe level.
There may be more correct answers than the ones listed.

Do you think engineers are needed to design a hearing aid? Why or why not?

YES!!!
Engineers need to design the system that makes the hearing aid work
Engineers need to choose what materials they will make the hearing aid out of
Engineers need to test the hearing aid to make sure it works correctly
Engineers need to design the speakers that are used in the hearing aid

Do you know how a hearing aid helps people hear?

The hearing aid has a microphone that picks up sounds. The sounds are made louder (amplified) and sent into the person’s ear through a speaker.

Learning Objectives

By the end of this exercise, students should be able to…

Understand that sound can be transmitted mechanically through a string

Materials

Each group needs:

(1) Yarn Cup Telephone
(1) String Cup Telephone

Procedure

Give each group an activity handout. Have them answer the Brain Challenge questions on the Mechanical side of the page. The Data Engineer should record all answers. Give the students 5 minutes.

Read the instructions to the students step by step. Have students raise their hands after they complete a step so the instructor knows to move on.

ME – Take the cup telephones out of the micro-kit container. Make sure the strings are securely attached to the cups.

TE SE – Each engineer should grab one of the orange cups and stand away from each other so that the string is taut.

SE – Put your ear up to the cup and wait for the TE to talk.

TE – Talk (do not yell) into the cup.

SE – Describe what you heard. Could you hear the TE? Was the TE’s voice loud/soft, easy/hard to understand?

DE – Record what the SE heard through the cup telephone.

EE – Trade places with the SE and repeat the experiment.

DE – Record what the EE heard through the cup telephone.

ALL – Repeat the process with the green cups.

After all groups have completed testing of both orange and green cup telephones, have the students answer the Engineering Analysis questions at the bottom of the Mechanical page. The Data Engineer should record all answers. Review the answers with the students.

Learning Objectives

By the end of this exercise, students should be able to…

Understand the goal and necessity of amplification
Explain how a hearing aid helps people who are hard of hearing
Understand the engineering design process

Materials

Each group needs:

(1) Snap Circuit (SC) Board
(2) Black Snap Wires
(2) Red Snap Wires
(2) Battery Holders (B1)
(3) Resistors (R1,R3, R5)
(1) Capacitor (C3)
(1) Switch (S1)
(1) Power Amplifier (U4)
(1) 7Snap Wire
(1) 4 Snap Wire
(3) 3 Snap Wires
(2) 2 Snap Wires
(2) Single Snap Wires
(2) Speaker Stands

Circuit Schematic

Layer 1

B1 goes from A9 to C9

B1 goes from E9 to G9

U4 goes between D6, D7, F6, F7

Single snap goes on A7

3 snap goes from E2 to E4

7 snap goes from G2 to G8

Layer 2

S1 goes from C9 to E9

4 snap goes from A7 to D7

Single snap goes on A9

2 snap goes from G8 to G9

2 snap goes from F6 to G6

C3 goes from E4 to E6

Resistor goes from E3 to G3

Layer 3

3 snap goes from A7 to A9

Safety Precautions

Warn student not to put their ears too close to the speakers! While the speakers don’t get loud enough to damage hearing, getting too close may hurt.

Procedure

Read the instructions to the students step by step. Have students raise their hands after they complete a step so the instructor knows to move on.

ME – Take all snap circuit components out of the micro-kit container.

ME – Following the circuit assembly guide, put LAYER 1 on the SC board.

EE – Following the circuit assembly guide, put LAYER 2 on the SC board.

SE – Attach one black wire and one red wire to each speaker.

SE – Following the circuit assembly guide, attach the speakers to the circuit. Place the speakers as far apart as they will go.

TE – Make sure that the switch is OFF, and then put the batteries into the battery holders.

**Instructor – Go around and check each team’s batteries to make sure they are in correctly!

EE – Following the circuit assembly guide, attach the R1 resistor.

**Instructor – Make sure to clarify which speaker is the microphone and which is the speaker.

TE – Turn the switch to the ON position.

SE – Get ready to listen to the speaker.

TE – Talk into the “microphone” in a normal voice. Sometimes, humming or making a noise may also work.

DE – Record what the SE heard out of the speaker.

EE, ME, & DE – Take turns listening to the TE talk into the microphone.

EE – Switch the R1 resistor with the R3 resistor.

SETE –Test the circuit by talking into the microphone and listening to the speaker output.

DE - Record what the SE heard out of the speaker.

EE, ME, & DE – Take turns listening to the TE talk into the microphone.

ALL – Repeat steps with the last 2 resistors.

ME – When your group is done experimenting, carefully take apart the circuit and put the pieces away.