ExpEYES/C3/Characteristics-of-Sound-Waves/English-timed

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Time Narration
00:01 Hello everyone. Welcome to this tutorial on Characteristics of Sound Waves.
00:08 In this tutorial, we will learn to demonstrate:

How to generate a sound wave, frequency response of a sound source,

how to calculate velocity of sound, interference and beats of sound waves,

forced oscillations of a sound source.

00:29 And, show:

Xmgrace plots,

Fourier Transforms and

Circuit diagrams for our experiments.

00:38 Here, I am using:

ExpEYES version 3.1.0, Ubuntu Linux OS version 14.10.

00:49 To follow this tutorial, you should be familiar with ExpEYES Junior interface. If not, for relevant tutorials, please visit our website.
01:01 Let's first begin with definition of sound.

Sound is a vibration that propagates as an audible mechanical wave of pressure & displacement.

01:13 It requires a medium to propagate. The medium can be air, water or any metal surface.
01:22 In this tutorial, we will carry out various experiments to show characteristics of sound waves.
01:30 Let's perform an experiment to show frequency of sound waves.
01:35 In this experiment, ground(GND) is connected to Piezo buzzer (PIEZO).

Piezo buzzer (PIEZO) is connected to SQR1.

01:44 Microphone (MIC) is connected to A1. Here, Piezo buzzer(PIEZO) is a source of sound.

This is the circuit diagram.

01:55 Let's see the result on the Plot window.
01:59 On the Plot window, under Setting Square waves, set the frequency as 3500Hz.
02:07 Click on SQR1 check-box. Frequency of SQR1 is set to 3500Hz. A digitized sound wave is generated.
02:20 Move the frequency slider to change the waveform.
02:27 Click on SQ1 and drag to CH2. Input data of SQ1 is assigned to CH2. A square wave is generated.
02:40 Drag the mSec/div slider to set in compressions and rarefactions.
02:48 Click on CH2 and drag to FIT. Voltage and frequency of SQ1 are displayed on the right-side.
02:59 Move the frequency slider to set in sound waves.
03:04 Sound wave produced by the Piezo buzzer is shown in black colour.
03:10 Amplitude of the wave changes as Piezo buzzer is moved closer and away from the MIC respectively.
03:19 Now, we will demonstrate frequency response of Piezo buzzer.
03:24 On the Plot window click on EXPERIMENTS button. Select Experiment list opens. Click on Frequency Response from the list.
03:39 Two new windows Audio Frequency response Curve and Schematic open. Schematic window shows the circuit diagram of the experiment.
03:52 On the Audio Frequency response Curve window, click on START button.
03:59 Frequency response of the Piezo buzzer is set in. Frequency response has maximum amplitude at 3700Hz.
04:11 On the same window, click on Grace button. Grace window opens showing Frequency response Curve.
04:22 Now, we will measure velocity of the source of sound.
04:27 On the Plot window, click on EXPERIMENTS button.

Select Experiment list opens. Click on Velocity of Sound from the list.

04:41 Two new windows EYES Junior: Velocity of Sound and Schematic open. Schematic window shows the circuit diagram of the experiment.
04:55 On EYES Junior: Velocity of Sound window, click on Measure Phase button.
05:02 We can obtain different Phase values by changing the distance between MIC and Piezo buzzer.
05:11 Click Measure Phase button to obtain different Phase values.
05:16 From the various Phase values, we will use 178 deg and 106 deg to calculate the velocity of sound.
05:28 We can obtain these values when Piezo is kept close and 2cm away from the MIC.
05:37 To obtain accurate results, ensure that MIC and Piezo buzzer are placed on the same axis.
05:45 To calculate the value of velocity of sound, we have the formula as shown.

Velocity of sound obtained from the experiment is 350m/sec.

05:59 As an assignment, calculate the value of wavelength of sound. Formula: λ= v/f(Lambda = v upon f).
06:09 Now, we will demonstrate:

Interference,

Beats,

Xmgrace plot and

Fourier Transform of the two sources of sound.

06:20 To show Grace plots in the experiments,
06:23 make sure that you have installed:

python-imaging-tk,

grace,

scipy and

python-pygrace on your system.

06:34 In this experiment, we use two Piezo buzzers as source of sound.
06:41 In this experiment, Piezo 1 is connected to SQR1 and ground(GND). Piezo 2 is connected to SQR2 and ground(GND). This is the circuit diagram.
06:56 Let's see the result on the Plot window.
07:00 On the Plot window, set frequency as 3500Hz.
07:06 Click on SQR1 and SQR2 check-boxes. Frequency of SQR1 and SQR2 is set to “3500Hz”.
07:20 A digitized sound wave is generated.
07:24 Move the frequency slider to change the waveform.
07:29 Click on EXPERIMENTS button and select Interference of Sound. EYES: Interference of Sound window opens.
07:39 At the bottom of the window, change NS, that is, number of samples value to 1000.
07:48 Click on SQR1 and SQR2 check-boxes. Click on START button. Interference pattern is seen.
08:00 Now, click on Xmgrace button. A new window opens with a Grace pattern.
08:08 Now, we will show Beats pattern.
08:11 Click on EXPERIMENTS button and select Interference of Sound.

EYES: Interference of Sound window opens.

08:20 At the bottom of the window, click on SQR1 and SQR2 check-boxes.
08:28 Click on START button. Beats pattern appears.
08:33 Now, click on Xmgrace button. A new window opens with a Grace pattern.
08:42 Click on FFT. A new window opens with Fourier Transform.
08:49 To know more about Fourier Transform , please visit this webpage.

https://en.wikipedia.org/wiki/Fourier_transform.

08:55 Let us perform an experiment to show a low frequency sound wave. This is the circuit diagram.
09:03 Click on EXPERIMENTS button and select Interference of Sound. EYES: Interference of Sound window opens.
09:13 At the bottom of the window, set the value of SQR1 to 100 and check the box.
09:21 Click on START button, a low amplitude wave is displayed.
09:29 Click on FFT to obtain a Grace plot of Fourier Transform.
09:34 Let's summarize.
09:36 In this tutorial, we have learnt to demonstrate:

how to generate a sound wave,

Frequency response of a sound source,

how to calculate velocity of sound waves,

Interference and Beat pattern of sound waves,

forced oscillations of sound source.

09:56 And, have shown:

Xmgrace plots,

Fourier Transforms and

Circuit diagrams for our experiments.

10:04 As an Assignment-

Capture a sound burst

Hint: A bell or a clap can be used as source of sound. This is the circuit diagram.

10:15 This video summarizes the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it.
10:24 We conduct workshops using Spoken Tutorials and give certificates. Please contact us.
10:32 The Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
10:40 This tutorial is contributed by Kaushik Datta and Madhuri Ganapathi. This is Sakina Sidhwa.

Thank you for joining.

Contributors and Content Editors

Madhurig, Pratik kamble, Sandhya.np14