This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.
The raising and lowering of the whistle's pitch due to the alteration in the relative speed of the whistle as it goes by you, described by two terms that can be discovered by reading your homework assignment.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.Read more: http://wiki.answers.com/Why_is_the_pitch_of_a_train's_whistle_higher_as_the_train_approaches_and_loweras_it_moves_away#ixzz1DToTuS3j
It gets louder and then gets quieter
a change in the sound's frequency caused by the motion of the sound's source
That would be the Doppler shift of the sounds frequency as it approaches you and passes by.
This is known as the Doppler effect. As the train approaches you, the wavelength of the sound waves it emits are compressed, and therefore the whistle sounds higher. When the train is moving away, the wavelengths are extended, causing the whistle to sound lower. If the train were not moving at all, the pitch you would hear from the whistle would be somewhere between the high and low pitches you hear when the train is moving.
It is the effect that happens when waves like sound are moving in relation to another object. In the classic train whistle example, The whistle suddenly drops in pitch as it passes you and starts to move away from you. This is because the sound waves now are stretched out, giving them a lower pitch. It is useful. Doppler radar used in weather forecasting is one example.
it's frequency increases
It appears to have a higher frequency due to the Doppler Effect.
We all heard a whistle before, but when you are writing something and you want to type or write a whistle sound, it gets you thinking. If I were writing it i would put, WHEWWW, or, PHEWWWWWW. NO A whistle sound makes the sound Whistle
The sound a whistle makes is often described as "whoo" or "wee" depending on the pitch and intensity of the sound.