The time taken for the echo to be heard is = 3 2 0 m / s 2 × 4 8 m = 0.3 s. The total distance traveled by the sound is given as 2 × 4 8 m as it is reflected sound. T i m e t a k e n = v e l o c i t y o f s o u n d D i s t a n c e t r a v e l e d . So, if the obstacle is at a distance of 17 m at least, the reflected sound or the echo is heard after 0.1 second, distinctly.Īs the speed of sound is 320 m/s and the distance traveled by sound is 48 m are given in the question, the time taken is calculated from the formula, This is twice the minimum distance between a source of sound and the reflector. So the most important condition for hearing an echo is that the reflected sound should reach the ear only after a lapse of at least 0.1 second after the original sound dies off.Īs the speed of sound is 320 m/s and the distance traveled by sound is 48 m. If the echo is heard within this time interval, the original sound and its echo cannot be distinguished. This is known as the persistence of hearing.
The sensation of any sound persists in our ear for about 0.1 seconds. Certain conditions have to be satisfied to hear an echo distinctly (as a separate sound). Ordinarily echo is not heard as the reflected sound gets merged with the original sound.
As a result of reflection of sound wave from a large obstacle, the sound is heard which is named as an echo. Sound waves suffer reflection from the large obstacles. The source sound is a stick hitting a metal can.Like all waves, sound waves can be reflected. Sound Example : Multiple echoes produced under a parabolic bridge, Stanley Park, Vancouver, B.C. Sound Example : Reflected sound from the opposite side of a lake, heard as an echo. Compare: ABSORPTION, ACOUSTIC RADIATION, REFRACTION, TRANSMISSION. See also: BINAURAL HEARING, PHASING, SOUND PROPAGATION. Symmetrically-shaped surfaces produce symmetrical reflections, the most striking examples of which are the whispering gallery, where sound travels along the walls via repeated reflections, and the PARABOLIC REFLECTOR where all sound is reflected to the focus of the parabola. 9.3.6.3 Reducing Acoustic Responses Logically, the acoustic sound pressure environment. In general, concave surfaces focus sound waves, thereby concentrating the sound in specific areas, and convex shapes scatter sound, thereby promoting good diffusion. Typically, reflector designs that are very lightweight and have. Different surfaces have different reflecting powers, as measured by their ABSORPTION COEFFICIENT or REFLECTION COEFFICIENT. Sound reflection gives rise to DIFFUSION, REVERBERATION and ECHO.
Reflection of a sound wave at a barrier, as if from an imaginary source at an equal distance behind the barrier. See: CANYON EFFECT, DIFFUSE SOUND FIELD, SOUNDING BOARD. However, this law of reflection holds only when the WAVELENGTH of the sound is small compared to the dimensions of the reflecting surface.
the angle of INCIDENCE of a SOUND WAVE equals the angle of reflection, just as if it were produced by a 'mirror image' of the stimulus on the opposite side of the surface. The law for reflection is the same as that for light, i.e. If a sound is not absorbed or transmitted when it strikes a surface, it will be reflected.
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