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

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