I assume you meant you hear the noise from 2 - 5MHz and not from 2000MHz to 5000MHz where noise generally is not an issue. 2-5MHz is generally "noisy" when compared with the higher HF frequencies. Atmospheric noise and lightning crashes can often be heard hundreds of miles from the source. There is not much you can to to eliminate this noise.
It is MUCH better to eliminate the noise than to try to mask it. My guess is something inside your house is causing the noise. Typical noise sources are TV's (even when turned OFF), computers, computer monitors, alarm systems, touch activated lamps, etc.
If this is a battery operated radio, "kill" all power to your house by flipping the main circuit breaker in the breaker box to OFF. Does the noise go away or nearly so? If it does something inside your house is causing the problem. Unplug various electrical devices one at a time until the noise is reduced. Continue until you identify the culprit(s).
If killing all power to your house does not identify the problem then obviously something outside of your house is causing the noise. Typical culprtis are power lines arcing, electric fences, and / or devices in neighboring houses.
If you do not have an outside antenna, by all means install one. This often helps. One thing to remember, grounding the radio WILL NOT reduce the noise.
Dick AD4U