oscilloscope app for laptops

You don't want an oscilloscope.  You want room measuring equipment.

Here are the most common for enthusiasts:

• Room EQ Wizard (free, needs calibrated mic)
• OmniMic (my favorite, comes with mic)

Good luck.

Here's a thread over at DIYaudio for you as well:

https://www.diyaudio.com/community/threads/speaker-testing-and-measurement-software.305520/

ok thanx, I'll look into it