Noise.

Sound is the result of vibrations. Vibration is simply moving back and fourth of some object. When the vibration is very regular, when the sounding body sends out waves at absolutely regular intervals, the result is a musical sound. If the vibration is not regular, the effect on your ears is not all pleasing. The resulting sound is "noise".

The three differences between one sound and another are loudness, pitch, and tonal quality. Loudness of a sound depends partly on the distance from the object to the ear and partly on the amplitude of vibration of the sound-making object. Amplitude means the distance the vibrating body moves in its to-and-fro motion. The greater the movement is, the louder the sound will be.

The highness or lowness of a sound is called its "pitch". Pitch depends on the speed of vibration or the sounding object. The greater the number of vibrations that reach the ear every second, the higher will be the pitch.