[Figure 6.1] shows a girl standing a few hundred metres in front of a large building. The girl uses a signal generator and a loudspeaker to send a short pulse of sound towards the building. The sound has a frequency of 3700 Hz. A short time later, the girl hears an echo.

1. (a)State what is meant by the term echo.[1]
2. (b)(i)The pitch of the echo is the same as that of the original sound but the echo is not as loud. State what has happened to the amplitude of the sound wave,[1]
3. (b)(ii)the frequency of the sound wave.[1]
4. (c)The speed of sound in air is 330 m/s. Calculate the wavelength of this sound.[2]

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