Question

Curved surfaces which are used in the big hall to direct the sound waves towards the people sitting in a hall are known as
(a) megaphone
(b) hydrophone
(c) bulb horn
(d) echo

Answer 1

Hint: This work supports the law of reflection of sound waves and it is a big concave board and is set in such a fashion behind the stage that the speaker is at the focus.

Complete step-by-step solution:

Soundboard is employed to send the sound towards the audience during a big hall or auditorium. This works based on the law of reflection of sound waves. The Soundboard may be a big concave board and is about in such a fashion behind the stage that the speaker is at the main target . The sound coming from the speaker falls over the soundboard and gets reflected towards the audience. As a result, the audience sitting within the hall even at a far distance from the speaker can clearly hear what the speaker is saying. Additionally, the ceiling of the auditorium is also made curved, so that it also acts as a soundboard. The curved surface of the ceiling reflects the sound waves and it facilitates better hearing.
The sound which we hear after reflection is named echo or echo of sound. One can hear the echo by shouting loudly during a big hall. After shouting loudly, an equivalent sound reaches the ears after reflecting from the surface of the wall. Echo of sound are often heard by producing sound at an area surrounded by hills or big buildings. Thus, repetition of sound because of multiple reflections of the sound wave is called echo.
Option D is the correct answer.

Note: Simply put, a soundboard which takes multiple input signals such as microphones, instruments, iPods, DJ turntables, etc.and merges them together so that they are often sent to speakers as one signal.