Listening to reflected sound in Sound – Class 9 Science Experiment
Chapter Name: Sound
Activity Name: Listening to reflected sound in Sound
Activity Description:
In this experiment, you will explore the reflection of sound by using two long, identical tubes placed near a wall. By speaking softly into one tube and listening through the other tube, you will observe how adjusting the angles of the tubes affects the quality of the reflected sound.
Additionally, you will test how different materials placed against the wall influence the reflected sound.
Required Items:
- Two long, identical tubes
- Wall
- Flat objects made of different materials (steel and plastic trays, cardboard, cloth-draped tray, etc.)
Step by Step Procedure:
- Place the two long, identical tubes on a table near a wall.
- Ask your friend to speak softly into one tube while you use the other tube to listen.
- Adjust the angle of the listening tube until you hear the best sound.
- Note the angle at which the tubes are positioned for the best sound clarity.
Experiment Observations:
- You will find that you hear your friend’s voice best when the tubes make equal angles with a normal to the wall.
- If you lift one of the tubes slightly above the table, you will not be able to listen to the sound clearly. The incident and reflected sound-carrying planes will no longer be in the same plane, leading to unclear sound.
Precautions:
- Handle the tubes and objects with care to avoid any damage.
- Ensure that the tubes are identical in length and shape for accurate results.
- Speak softly into the tube to maintain consistent sound levels.
Lesson Learnt from Experiment:
The experiment demonstrates that the reflection of sound follows similar laws as the reflection of light. When sound is reflected, the incident and reflected sound directions make equal angles with the normal to the reflecting surface.
Adjusting the angles of the tubes allows you to hear the best-reflected sound. Lifting one of the tubes disrupts the alignment of the incident and reflected sound-carrying planes, resulting in unclear sound.
