Which of the following best explains why an echo is heard when a sound is produced near a large, flat wall?
Sound waves reflect off the wall and return to the listener after a short delay.
Sound is a mechanical wave. When it strikes a large, flat, hard surface such as a wall, most of it bounces back into the same medium. This bouncing back of sound from a surface is called reflection. The reflected wave travels back to the listener; if it arrives after a small time delay (at least about 0.1 s), the listener's ear hears it as a separate sound, and that repeated sound is called an echo.
Sound does not pass through a solid wall and reappear on the other side to form an echo; passing through would be transmission, not reflection. Sound is not stored by the wall and re-emitted slowly either, because a wall does not absorb sound and then release it as sound again. So the only correct mechanism is reflection followed by a short time delay.
Hence, the answer is Sound waves reflect off the wall and return to the listener after a short delay.
Similar Questions
Which of the following statements is/are true about the loudness and softness of a sound wave?
(i) A loud sound has less amplitude as compared to a soft sound.
(ii) A loud sound has more energy associated with it as compared to a soft sound.
(iii) The loudness of a sound wave is the measure of the response of the ear to the sound.
Which of the following sounds has the lowest pitch?
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If two sounds have the same frequency but different amplitudes, what will be different?
Which of the following statements best explains why sound can NOT travel through a vacuum?
Which of the following actions would most effectively reduce reverberation in a large auditorium?
When a tuning fork vibrates and produces sound, what type of waves is created in the air?
Which of the following conditions is necessary to hear an echo clearly?
If a musical instrument produces a sound with a frequency of 200 Hz, which of the following frequencies will produce a sound of higher pitch than this instrument?
A group of engineers is tasked with designing a lecture hall for maximum speech intelligibility. Which combination of features should they prioritize to minimize reverberation?
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