Link to Original Source
Yes, the article referenced doesn't point to the actual study directly, a but with a bit of goggling I found:
The battleground — where this degradation takes place — is at ISP interconnection points. These are the places where traffic requested by ISP customers crosses between the ISP’s network and another network on which content and application providers host their services.
This test measures whether interconnection points are experiencing problems. It runs speed measurements from your (the test user’s) ISP, across multiple interconnection points, thus detecting degraded performance.
What I don't understand is why people assume congestion is intentional throttling by ISPs for them to profit later with imagined fast lanes. Isn't the simpler assumption that it costs ISPs money to add interconnection capacity. And since their customers don't/can't choose ISPs based on the quality of their connection all the way to the popular content providers, the ISPs don't spend money on those upgrades? Usually the only thing customers have to go on and promised is the maximum download/upload speeds quoted by the ISP for the last mile.
If you are a windows user, Christian Zeitnitz offers a PC based Soundcard Oscilloscope free for non-commercial use. It also has a frequency spectrum waterfall diagram, x-y plots. Easy to install and run. Fun to speak into your microphone to test it out.
Only suitable audio speed signals like XOScope. I.e., 20-20000Hz from 44.1kHz sampling and 16-bit resolution. And without external hardware voltage dividers/protection the usual warnings about blowing up your soundcard if you feed in voltage outside of ±0.7V into it.