Why we do not hear any sound when a helicopter fly in the Night?

Question

When a helicopter fly in the Night we do not hear it's sound, But In the morning we hear a lot of sound. Can any one tell me Why?

Answer 1

legislation.  Helicopters have a minimum safe altitude of flight which is higher at night than during the day.  This accounts for the difference in perceived volume.

Answer 2

really, you can't??!

i can hear the sound of helicopters at night, and i think everyone can.

Answer 3

Whether in day or night, the helicopter, while flying makes noise. You might have not noticed or paid attention to it.

During night, the audibility of the noise is much greater than the day as the night is cool and without much disturbance.

Answer 4

we used sleep at night time when we sleep our body is unser complete rest and our brain undergoes various sleeping stages.we dont hear any sound when a helicopter fly in the night because we will be in a subconcious state

Answer 5

They may be flying at a higher altitude at night than they are during the day.I can here them day and night.Sometimes wind can help carry sound also.

Answer 6

bcoz at night u r asleep!

hahahah!

Answer 7

Hello,,could be you just weren't listening. Maybe it sounded like your wife and you blocked it out.

Answer 8

may be you are dump

Answer 9

u wd have slept thats all........