Did I relapse listening to porn?

This sounds very suspicious to me. I have never browsed the web and clicked a link "that turned out to be a snippet of audio from a porno"! Where were you browsing? What did the link say (or look like). Why did you listen to the whole thing? There seem to be a lot of wilfulness in what you did. You have tried to make it seem completely accidental, but the clues are there to suggest otherwise. Technically, it doesn't fall under the definition of pornography in the Eng. dictionary:
"Writings, pictures, films, etc, designed to stimulate sexual excitement". However, I am sure you will agree that the audio was: "designed to stimulate sexual excitement". This is evident from the rush of blood to your penis - ready for action!

It is your choice whether to reset to zero or to tell yourself that you have been clean for 7/8 days. But if you decide not to reset, I strongly advise you to do so if you repeat this behaviour. It is not conducive to stopping artificial, sexual stimulation of dopamine and repeated sessions of listening to people groaning and moaning while they fuck each other is not good.

 

I personally would reset my porn counter for that, but it's more about your feeling and why you are doing this.

I used to put the sounds of porn on my mp3 player and MO to it, so for me it totally counts as viewing porn.