Windows 7: Inconvenient sound from my Toshiba Notebook

Model: Toshiba NB 250
OS: Windows 7 Professional 32-bit
1gb RAM
250GB HDD

Problem: It started during when its still new and was exploring different settings in my toshiba notebook then i suddenly encountered( This is according to my memory) a setting where i can configure something and with symbols of wave in the top of the monitor( in the settings menu there was a visualization of the notebook and a wave) so i selected that and saved after saving i thought it has no effect on the system or my notebook or for short it wont make the notebook inconvenient to use after a few months (3 months to be exact after doing that setting) i forgot where it is now and how i managed to reach that settings and i was surprised that one day when i closed my notebook screen (still on not in hibernate or sleep mode) the notebook will sound off an alarm thats quite disturbing and annoying but when i place my hand above the monitor it will stop or any object.



i explored all settings of windows but cant find that settings panel even command prompt

can anyone help me if someone encountered a problem like this or a suggestion -thnx in advance