Introduction
With today’s experiment, we will learn how to focus sound. Nowadays, scientists have discovered a way to focus sound waves by transmitting the ultrasonic wave in a straight line that could eliminate the audible sound of its path. But the problem is that the focalization of sound is very costly. So, we decided to perform this experiment to lower the cost of focusing sound.
Aim
To develop a low-cost process of focusing sound waves with the help of the parabolic dish and the sound-absorbent material.
Theory
1. The process in which diverging sound waves, spherical sound waves, or plane sound waves get converted into converging sound waves is called sound focusing.
2. The focusing of sound is done through reflection and refraction.
3. The factors that affect the quality of sound focusing are the size and shape of the focal region and the amplification (of the sound pressure).
4. To Obtain clear images in ultrasonic microscopy, holography, and ultrasonic viewers, sound focusing is used. It is also used in scanning systems for medical diagnostic instruments with an ultrasonic beam.
Requirements
1. One-end open soundbox of measurement (20.75 X 15 X 15)inches which are made up of particleboard
2. Speaker
3. Parabolic Dish
4. Sheetrock
5. Styrofoam
6. Fibreglass
Procedure
Step 1: Take the soundbox.
Step 2: Suspend the speaker in a cradle so that it can move one inch inward and outward.
Step 3: Transmit a constant sound frequency at a level of 105 DB using the speaker.
Step 4: This project will consist of three small tests and one final test.
Step 5: In the first test, determine whether the material of the parabolic dish affects the sound focusing quality.
Step 6: Take the measurement from different locations around each of the parabolic dishes with the help of a decibel meter.
Step 7: In the second test, determine whether the position of the speaker affects the sound focusing quality. To check whether the speaker directed the best sound from 2, 3, or 4 inches, take the measurement using a decibel meter from a different position from the back of each dish.
Step 8: In the third test, determine whether styrofoam, sheet glass, or fiberglass absorbed most of the sounds. Cut these materials to line the walls of the soundbox.
Step 9: Measure the sound of each material from 1 ft. outside the box.
Step 10: In the final test, combine the result of the previous three tests and check whether sound focusing is possible.
Observation
1. We observed from our experiment that a glass dish was most capable of sound focusing in the first test.
2. In the second test, we noted that if we place the speaker 2 inches from the rear of the dish, then the sound focuses more.
3. Our third test noted that the fiberglass insulation was the most capable of sound focusing.
Result
1. In our test, we noted that when the speaker is placed 2 inches from the back of the dish, situated inside the fiberglass insulation-coated walls of the soundbox, it focuses most of the sound.
2. We successfully focused 3-5 ft in front of the dish, and in other directions, the sound spread was limited.
Conclusion
We learned how to focus sound and concluded that the sound could be focused with the help of a parabolic dish and a sound-absorbent material in a very cost-effective way.
VIVA Questions With Answers
Q.1 What was the aim of your experiment?
ANS. To develop a low-cost process of focusing sound waves with the help of the parabolic dish and the sound-absorbent material.
Q.2 What do you understand about sound focusing?
ANS. The process in which diverging sound waves, spherical sound waves, or plane sound waves get converted into converging sound waves is called sound focusing.
Q.3 In what position did you place the speaker for sound focusing?
ANS. 2 inches from the back of the dish.
Q.4 Which glass was most capable of focusing sound?
ANS. Fiberglass insulation was the most capable for sound focusing.
Q.5 What is the use of sound focusing?
ANS. To obtain clear images in ultrasonic microscopy, holography, and ultrasonic viewers, sound focusing is used. And also used in scanning systems for medical diagnostic instruments with an ultrasonic beam.

Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.
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