|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.
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:
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-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.|
|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.|
|09:36||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:
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.