jDFT is a utility for Windows that allows you to analyze the frequency spectrum of an audio in real time, you just have to connect the audio source to your computer and start analyzing it.
It is a very functional program, works very fast and does not involve complication, being also completely free.
jDFT is showing all frequencies in the form of colored graphics, which makes reading easier when diagnosing a problem with the computer's sound.
NOTE: For proper operation you need to have DirectX 9.0 or higher installed beforehand.
You can free download jDFT 32, 64 bit and safe install the latest trial or new full version for Windows 10 from the official site.