We hear the sound of humming bees, but not the vibrations of a pendulum, because the frequency of the sound produced by bees falls within the audible range of human hearing, while the frequency of pendulum vibrations is below this range. In other words, bee sounds are within the 20 Hz to 20,000 Hz range, whereas pendulum vibrations are typically below 20 Hz (infrasound).
Here’s a more detailed explanation:
Sound and Frequency:
Sound is created by vibrations that travel through a medium like air. The frequency of these vibrations determines the pitch we hear; higher frequencies correspond to higher pitches.
Audible Range:
The human ear can detect sounds within a specific frequency range, known as the audible range, which is roughly between 20 Hz and 20,000 Hz (or 20 kHz).
Bee Sounds:
The rapid beating of a bee’s wings produces vibrations that fall within the audible range. This allows us to hear their humming sound.
Pendulum Vibrations:
The vibrations of a pendulum, while present, occur at a much lower frequency than the audible range. They are usually below 20 Hz, falling into the infrasound category. Because these vibrations are not within the range of our hearing, we do not perceive them as sound.