Describe some practical applications from daily life based on multiple reflection of sound.

Uses of multiple reflection of sound:

1. Megaphones or loudhailers, horns, musical instruments such as trumpets and shehanais, are all designed to send sound in a particular direction without spreading it in all directions.
In these instruments, a tube followed by a conical opening reflects sound successively to guide most of the sound waves from the source in the forward direction towards the audience.
The fig. below shows us some musical instruments. 

Fig. Multiple reflection of sound in a megaphone or horn.

2. Stethoscope: In a stethoscope, the sound of a patient’s heartbeat is guided along the tube of the stethoscope to the doctor’s ears by multiple reflections of sound.

Fig. Mutliple reflections of sound in the tube of a stethoscope.

3. Curved ceilings concert halls The ceilings of concert halls, conference halls and cinema halls are made curved so that sound after reflection reaches all corners of the hall. 

Fig. 12.21. Curved ceiling of a conference hall

4. Sound boards: In large halls or auditorium, large concave wooden boards are placed behind the speaker. The speaker stands at the focus of this concave reflecting surface. After reflection, the sound is spread evenly towards the audience. This makes the speech readily audible even at a distance.

Fig. 12.22. Sound board used in a big hall.