Question

Environmental hum has a sound frequency of-
A) 0.1 Hz
B) 1.0 Hz
C) 40 Hz
D) 100 Hz

Answer 1

Hint: There is a constant sound of low frequency that can be heard in total silence, it comes from nature. Its frequency is not as low to pass unnoticed by humans, neither is that high to be considered as noise.

Complete Answer:
The hum is a collective sound of mystifying vibrations produced by oscillation of earth. The hum can be produced by long ocean waves impacting the sea bed or the collective sound produced by animals present on the earth. Sound of wind can also be considered to be a part of environmental hum. The frequency of the produced sound is low but constant and may even cause irritation.

Therefore, the correct answer is- C. 40 Hz.

Additional information:
- Hum is a low-frequency, persistent humming or droning noise. It is not necessary that it gets noticed by each person, it might remain unnoticed by some people.
- Many scientists have observed the environmental hum at different parts of the earth, which is why it can be considered constant worldwide.
- As the frequency of the environmental hum is 40 Hz, people with strong hearing power can notice it. It is enough to get noticed by the human ear.
- There are instruments which can be used to measure frequency of this hum which scientists use to record it. Such instruments are called decibel meters.

Note: Environmental hum includes only naturally produced sounds. Sounds produced by anthropogenic activities cannot be incorporated in the environmental hum. Anthropogenic causes for sound production such as industries, locomotives, engines, amplified sound from musical events, etc. does not contribute to the environmental hum.