SOTM LAB: P15

I. TEACHER NOTES AND GUIDELINES

TITLE OF LAB- THE SOUNDS AROUND US!

DEVELOPERS OF LAB- Christopher Eachus (JD878)Bill Frandino (JD886)Amy Matts (JD563)

OVERVIEW OF LAB

DESCRIPTION- In this lab students will experiment with a sound sensor and varying frequencies, amplitudes and types of sound. Students will first examine sinusoidal waves produced by a sound generator. Frequencies and periods of sound waves will be observed using the FFT and Scope displays. Students will then have the opportunity to experiment with many types of sounds. At the conclusion of the inquiry, students will be able to distinguish different types of sounds by comparing graphical waveforms. Ref: SWS Library P32.

CURRICULUM CONSIDERATIONS- This lab is intended to be an introduction to sound and a reinforcement of wave principles. Students should have previous knowledge of frequency, period, wavelength and amplitude. Mechanical forms of energy should have been discussed. Students should have a thorough knowledge of graphs and graphing exercises. The graphical relationships of direct, indirect and inverse should be known.

SAFETY CONSIDERATIONS- Students should be cautioned that various amplitudes and frequencies can be harmful to themselves and others in the classroom. Identification of the ‘threshold of pain’ may be important at this point.

BACKGROUND INFORMATION:

A. SCIENTIFIC VIEWPOINT- The underlying concept of this inquiry is that sound travels in waveform and that different sounds are represented by different wave shapes and sizes. Students will be able to improve their ability to make inferences between graphs and physical characteristics. Observation skills will be extensively used in drawing conclusions for this lab.

B. COMMON MISCONCEPTIONS Sound does not require a medium. Sound travels in the form of transverse waves. Sound waves transmit matter(air), not energy. Radio waves are sound waves. On an oscilloscope, peak to peak is wavelength.

OBJECTIVES:

After completing the lab, students will be able to:1. identify the relationship between loudness and amplitude.2. identify the relationship between pitch and frequency.3. compare and contrast waves from differing sources.4. calculate frequencies/period.

EQUIPMENT/MATERIALS

*Computer with PASCO 750 interface*Sound sensor*Signal Generator (on 750 interface)*Speaker*Various sources of sound(i.e. tuning forks,glass, metallic objects)

ADVANCE PREPARATION

Lab groups should be preassigned by the teacher with a maximum of four students per group.

One set of apparatus should be available to the teacher and set up under the observation of the entire class.

II. PRE-LAB

PRE-LAB EXERCISE TO ELICIT STUDENTS’ PRIOR KNOWLEDGE AND MISCONCEPTIONS

The teacher will ask individual students to produce various sounds vocally as well as by any other method possible.

Ask the students to write the answers to the following questions.1. How was your sound produced?2. What was similar between all the sounds produced in the classroom?3. What was the difference in producing a louder sound versus a softer sound?4. Could you identify the sounds produced if your eyes were closed?

Note: Teacher should have students close their eyes and produce several sounds at this point and have students identify the sounds.

5. List as many differences as possible between the sounds which were produced?

6. Draw diagrams of two different sound waves.

DISCUSSION OF PRECONCEPTIONS

Upon completion of the above questions, discuss the responses to the first five questions.Note: Students will have various degrees of prior knowledge. Recognize all

plausible answers.

Important Points:

Sounds are produced by vibrations.Not all vibrations produce sound.Energy affects produced sound.Each sound produced has its own characteristics.****Avoid using the terms pitch and volume.*****Several students should draw their examples of graphs(Question 6) on the board or overhead. Brainstorm for physical similarities and differences between each wave drawn.

III. EXPLORATION OF SCIENTIFIC PRINCIPLE & INTRODUCTION OF EXPERIMENTAL PROTOCOL

PROBLEM

What are the differences in the graphs of two sound waves produced by two different sounds?

EXPERIMENT AND TECHNICAL OPERATION OF EQUIPMENT

The teacher will set up the laptop computer, PASCO 750 interface, thePASCO Signal Generator and the PASCO Sound sensor. The teacher will speak into the Sound Sensor while asking the students the following questions.

1. What do you see occurring on the FFT display?2. What do you see on the Graph/Scope display?3. What are the similarities and differences between the Graph and Scope

displays?4. What caused these displays to occur?5. What changes occur as I speak into the Sound Sensor?6. Sketch graphs of the FFT display as produced by two different sounds and

note on the graphs the perceived differences in sounds.7. Sketch graphs of the Graph/Scope display(static) as produced by two

different sounds and note on the graphs the perceived differences in sounds.8. Produce sounds of various frequencies using the Signal Generator and view

the graphs produced.9. Produce a sound with the Signal Generator and have the students free-hand

produce a FFT display and a Graph/Scope display.10. Produce a second sound of a different amplitude and frequency and have the

students produce new displays. Discuss the student produced graphs.NOTE: Be sure to note the similarities and the differences in the student produced graphs.11. Produce the FFT and Graph/Scope displays for the sounds produced.12. Discuss these graphs and make sure the use of the equipment is clear.

TEACHER NOTES IN EQUIPMENT SETUP AND USE

1. Plug in PASCO 750 Interface, Signal Generator and Sound Sensor into the laptop computer prior to turning on laptop(Laptop will not recognize interface otherwise).

2. Double click on Science Workshop. Maximize window.3. Click and drag analog plug to Channel A. Type S and press enter or select

Sound Sensor.4. Click and drag Scope icon and drag Scope display to bottom of screen. Do

the same to the FFT icon and the FFT display.5. Click and drag Graph icon to the ear symbol and drag display to side of the

screen.

6. Double click on ear symbol. Change Sound Sensor Sensitivity from Low(1x) to High(100x). Click on OK.

7. Click on Sample V on interface icon and Signal Generator display appears. Drag Signal Generator display to side.

8. Sample the various AC Waveforms by clicking the On button. Try each wave shape and vary the Amplitude and Frequency of each.

TO RUN A TEST RUN OR DEMO FOR CLASS9. Bring up Scope display and maximize. On right side of display, change from

I.0 V/div to 0.01 V/div and use line thickness buttons for thickness of graph.

10. At bottom of Scope display, change to 2.00 ms/div and 10,000 sample/s.

11. Use maximized display as voice analyzer.

12. Bring up Signal Generator and set for 0.2 to 0.3 V and a frequency between 200 and 500 hertz. Bring up Scope display and change Signal Generator while noticing changes in wave patterns on Scope display.(Note: Indicate that the horizontal distance between waves is not wavelength)

IV. ELABORATION OF SCIENTIFIC PRINCIPLE: INQUIRY-BASED STUDENT INVESTIGATION

PROBLEM

What characteristics of a sound can be determined by its graphical waveform?How is it possible to identify objects by sound or voice recognition?

HYPOTHESIS OR PREDICTION

Analyzing the graphical output of sounds will lead to the description of the sounds which produced the graphs. Specifically, frequency(pitch), amplitude(loudness) and period of the sounds can be identified.

EXPERIMENTAL DESIGN

What sounds do you want to identify by waveform recognition?How many variables do you need to consider?How many waveforms do you need to consider to recognize a sound? Checkpoint: Teacher checks students’ experimental design for feasibility.

Check the type of sounds to be identified(Should be simple sounds and waveforms to start with).Check the number of sounds the student wants to identify(Not too many)Check variables.Check waveforms to be analyzed.Assist students in learning how to permanently record collected data.

PLAN FOR DATA COLLECTION & ANALYSIS

When you are setting up for your data collection:Carefully follow the procedures given in Equipment Setup and Use.Which graphs will you need for your prediction?What variables are on each of the graphs which you have produced?What Controls will you set in order to make a comparison?To what degree of accuracy do you expect your predictions?How will you make your comparisons between graphs?How will you make your comparisons between sounds(general characteristics or specify actual sounds)?

Checkpoint: Teacher should check equipment setup.Teacher should check students’ plan for feasibility.Teacher should check students’ ability to use equipment(i.e. produce sounds, produce graphs, record graphs)Check number of trials and types of sounds students desire to record.Check method of data collection.

CONDUCTING THE EXPERIMENT

Are the students recording appropriate sounds?Are students staying on task?

Are the students properly recording data?Checkpoint: Teacher should monitor students’ investigations in progress.

ANALYSIS OF DATA

Are students correctly interpreting the graphs(units, etc.)?Are students making appropriate interpretations of graphical output?Checkpoint: Teacher should be making continual checks of students’ methods and interpretations throughout process.

DISCUSSION OF RESULTS

COMPAREWhat factors change with each new sound produced?Did the type of change in variables agree with your predictions?Is there enough data to exactly predict the source of the sound?How do our preconceptions change with the outcomes?

Are some reinforced?Are some dispelled?

Checkpoint: Teacher should be checking for agreements/disagreements with individuals and groups. Discussion of issues should be encouraged at this point.

PERSUADEList class/group predictions as shown by experiment.Students should list reasoning for the predictions.Come to a class/group concensus of predicting sounds and their graphical waveforms. Introduce the terms pitch and loudness. Reinforce these terms with definitions and graphical waveforms.

RELATEAsk students for concepts elicited by doing this lab.Ask students for other investigations which might be possible with this equipment.Groups of students should write up a general procedure for an elaboration lab which can be completed.Checkpoint: Teacher should read and discuss lab elaborations with groups for feasibility. Time, difficulty and applicability should be considered.Discuss Real World applications.

APPLICATIONSWavelengthVelocity of waves(Temperature, Mediums,etc.)Interference of waves(Nodes, Antinodes, Standing waves)Doppler EffectSonic Spectrum(Ultrasonic, Infrasonic, Sonic booms)Longitudinal waves(Compressions, Rarefactions)

V. EVALUATIONPOST-LAB SURVEY OF STUDENTS’ CONCEPTIONS

Students may retake the Pre-Lab Exercise. All students should be able to complete the Pre-Lab Exercise with success. Discuss the answers to the exercise with the addition of the terms pitch and loudness.

TRADITIONAL

1. Using complete sentences, thoroughly define the relationship between the pitch of a sound and the frequency of the sound wave.(Note: Students should be able to use the term – direct relationship)

2. Using complete sentences, thoroughly define the relationship between the loudness of a sound and the amplitude of the sound wave.

3. Using complete sentences, define the relationship between the amplitude of a wave and the energy of a wave.

4. Draw each of the following waves.A. High frequency, small amplitude.B. High frequency, large amplitudeC. Low frequency, small amplitudeD. Low frequency, large amplitude

5. In terms of pitch and loudness, describe each of the above sound waves.

ALTERNATIVE ASSESSMENTS

1. Teacher may produce hard copies of the graphs of various sound waves and a list of the objects which produced those sounds. Have the students do a matching column.

2. Teacher may produce various sounds and have the students freehand draw graphical waveforms and describe reasons behind their graphs.

3. Using the Laptop and PASCO equipment, students can produce graphs of other students voices or sounds and produce a test of identifying students by voice prints.

4. Students can write a ‘future’ news article about the use of voiceprints in identifying criminals or others.

Other forms of alternative assessment of content, skill and attitudinal objectives may be created and scoring rubrics may be written.

Acknowledgments: This material is based upon work supported by the National Science Foundation under Grant No. ESI 9618936. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.