Final answer:
The sound produced by every vibrating body cannot be heard by us because vibrations may be outside our hearing range (20 Hz to 20 kHz), may have an amplitude too small, may be absorbed by the medium, could be obstructed by environmental factors, or because there is no medium like in space for sound to travel.
Step-by-step explanation:
Vibration is indeed necessary for producing sound, but not every vibration leads to a sound that we can hear. The range of human hearing is typically from about 20 Hz to 20 kHz, and so vibrations that fall outside of this frequency range are not perceived as sound by the average person. There are several reasons why the sound produced by every vibrating body cannot be heard by us.
Firstly, some objects may vibrate at a frequency that is too high (ultrasound) or too low (infrasound) for our ears to detect. Secondly, the amplitude or energy of the vibration may be too small to create sufficient sound waves to reach and effectively move our eardrums. Also, higher frequencies are more easily absorbed by the medium they travel through, so they may dissipate before reaching our ears.
Additionally, environmental factors such as distance, obstacles, or competing noises can prevent sound waves from a vibrating object from being heard. In a vacuum, such as space, there is no medium for the sound waves to travel through, and hence no sound is heard. Lastly, the sensitivity of an individual's hearing can also affect whether they perceive a sound; this varies from person to person, and can be affected by factors such as age or exposure to loud noises.