This is because as the train moves towards you it emits the next wavelength closer to you than where the first one was emitted from. Frequency is inversely proportional to wavelength, so if the wavelength is less the frequency must be more. The speed of sound is not changed. The air isn t going to change its properties just because a train is coming towards you. Chapter 19 Review Questions 3.
Frequency is the number of vibrations per second the sound makes.
Pitch is the lowest frequency of the sound that we hear. The paper cone vibrates, pushing the air and then pulling away so the air expands again. This makes the air vibrate, causing a sound wave. Air is a poorer conductor of sound than either solids or liquids. The speed of sound is faster in water than in air, and faster yet in steel than in water.