What does it mean when you hear a door closing and a knocking sound on the computer and how to handle it.?

Please answer as soon as possable

Well yea, duh- I think they know that one already. Here is what is going on: You have sound settings on your Yahoo messenger and any other messenger you may be using. Because I do not know your computer knowledge, I will guide you as if you never touched one before-
The messenger is the buddy chat window that initiates when you log into the internet. Once it is opened you need to go to the top of the window under Messenger, once you click that you will click Preferences... once here you will find the "Alerts and Sounds" when in this window, you can uncheck enable sounds box.

Hope this was helpful

your friends are either signing on or off and you control it by the volume

agree with first answer... if you don't want to turn the volume down then log out of your messenger.

most probably you are using yahoo messenger.
in the preferences menu, there is an option to turn off this sound.

it means ur friend(s) having yahoo messenger have signed in(knock)or signed out(closing sound)
open yahoo messenger go to conseration menu and click on preferences and change the settings

when u hear the sound if u can see the pop up also in screen,there is a link called "change",click that and u can see lot of options, there u deselect this property

It means that you have some sort of Instant Messenger on, and your friends are signing on and off. You can adjust the volume of it but adjust the volume control on your computer.

Door Closing, A friend is now offline
Knocking, a friend is trying to get in touch with you

Hello , that is a strange sound to new users of the messenger services that are out there and if that is happening you should see a brief display that someone is signing off and their name appears on the far right bottom corner. This is nothing to be alarmed about go to the options folder and change the preference.