Digital

There are some people who do strange things to increase the quality of their sound or picture. There are $300 HDMI cables. Some people use a black marker around the edge of their CD's. They just don't get it. Digital technology is based on numbers, encoded in binary form, on and off. The great thing about binary is that there is no gray area. The signal is above a high threshold, it is a 1. If it is below a low threshold, it is a 0. It is not the same threshold. For example, in the system known as TTL, a 1 is above 2V, and a 0 is below .8V. There is a gap between these, and that prevents errors. So a bit of noise on a signal will not be able to cause a bit to switch.
If you want to test this, you must use scientific methods. People tend to see and hear what they expect. You need to have someone else switch the signal. It would be best if they did not know what you are doing, so they could not be able to inadvertently tip you off.