An echo is weaker than the original sound because the sound wave imparts energy to the surface from which it bounces. When a sound wave is directed at a distant surface, particles of air in the path transmit the energy to the next particle, until it reaches the surface. When the sound wave hits the surface, it transmits energy to it. This loss manifests itself as a weaker return signal.Continue Reading
An echo is strongest when the original sound wave strikes a hard, even surface. Soft surfaces and uneven surfaces absorb more energy, so there isn't much left in the return signal and the echo is weaker.
Additionally, the farther away the surface is, the weaker the echo. The intervening particles of air lose a little energy each time they transmit the sound wave to the next particle, so for great distances, the echo is weaker even when returning from a very hard, even surface.
If a surface is very close to the original sound wave, then there isn't an echo at all - but a reverberation. The leading end of the sound wave returns to the origin even before the trailing end has hit the surface, so a continuous sound is heard.Learn more about Optics & Waves
When sound waves strike a surface, they reflect off of that surface and can return to the source of the sound as an echo. To a listener, this may be identical to the original sound, just delayed and possibly distorted by its path through the air. If the echo arrives quickly enough, it may seem to be part of the original sound, forming a reverberation instead of an echo.Full Answer >
Echoes are created by sound waves being reflected off of a large obstacle. Conditions have to be just right for the echo to be heard as a separate sound.Full Answer >
The frequency of a sound wave determines what people hear as pitch. A higher frequency has a higher pitch, and a lower frequency is heard as a lower pitch. The frequencies that humans can hear range from 20 to 20,000 Hertz.Full Answer >
One good sound wave experiment is the cups and string experiment, which requires two plastic cups, a long string, two paperclips and something to make holes in the cups. Punch holes in the bottom and center of the cups, then thread each end of the string into the cups from the bottom and attach the paper clips. Pull the cups apart until the string is taught. Speak into one cup and listen from the other.Full Answer >