How do I keep the internal sound going but the external sound off?

I call radio programs and I record them by playing a software that records the sound. Now when im on the phone I want to turn off the sound externally so its not playing in the background while im on the phone. But I dont want the sound to be off internally so that it can be recorded. Before u say it cant be done, i had a Toshiba labtop that did this. You can keep the sound going internally but extrenally it let you turn it off....now i have a new labtop...and it does not allow that.

I know you can plug in something to the headphone jack and thats better then nothing....but...obviously just pressing a button is more practical...plus...i assume if u keep putting something in the headphone jack over and over and over that there is wear and tear on that jack waters

I know on a desktop u can just have speakers already plugged in and turn them off but this is for labtop

You do not say what model the new laptop is but what happens if you select mute? Doesn't it have a mute button?