Electrical Sound in MacBook Pro 13" 2015

I've searched a lot about it but haven't been able to find any question or answer similar to mine. I have MacBook Pro 13" 2015 with iStatsMenu installed. The reason why I mentioned iStatsMenu is that it shows me the RPM value of existing fans.

I sometimes hear quite electrical sound. It doesn't always happen, but it especially happens little bit loudly when I download something, meaning when there is a high load in network. At first, I thought it was CPU, but in under heavy load or normal load I don't hear that sound that loudly. By the way, I feel like I have to define the meaning "loud" in this context, it is like the room should be quite, and you need to get little closer to the body of your MacBook Pro.

I have another MacBook Pro, which is mid-2014 15" and I realized that it has a similar sound, as well. But its fans are usually around 2000 RPM, so I wonder if the fans' noise is blocking it since it is not that loud. I also made a similar check in my wife's old MacBook Pro, which is early 2011 and I heard a similar sound in that too. But again my new MBP is little louder, I assume it is because fans are usually 0 RPM, and which is really nice by the way, probably because of the new Intel CPU architecture, Broadwell. Some people say that sound is coming from fans, and I don't think so since fans are at 0 RPM and I still hear it. I wonder if it has anything do to with network card, which would be wireless card in this case.

So my question is whether as a MBP owner you hear a similar sound in your MBP? I would like to especially hear from MBP 13" 2015 owners. You can best hear it when you download an update or make a speed test at www.speedtest.net since it heavily uses your network bandwidth to download and upload for testing.

By the way, when I say electrical, I couldn't really find a better way of describing it. It is like a buzzing sound, but it gives you the impression of an electrical sound. It not a continuous sound like whining. I think buzzing can be a good candidate to describe it. But this sound effect is kind of close to that https://www.youtube.com/watch?v=m5mmw9qphkE&spfreload=10

Thanks in advance. If you guys cannot hear it, I will have to take it to Apple Store, but I am in middle of Doctor of Computer Science degree pursuit so I don't really want to leave my laptop for a week or so, which doesn't necessarily mean that it will take that long though.