That's the whole point... abstract, highly abrasive, atonal, anti-musical... insane! He achieves this with the jagged piece of metal he uses as a slide, and all those weird pedal combinations going at once.
Here's a link to Melt Banana's official site.
On the "Ear" section in particular listen to the song "F.D.C. for Short." It's all done with guitar and effects... no synths or computers or anything whatsoever.
Now, for any who'd say that it's "not music", well...
...when dadaist Marcel Duchamp submitted his artwork Fountain (consisting of a urinal toilet laid on its back) to the Society of Independent Artists in Paris, 1917, and was challenged as to why they should even consider it 'art', his reply was as follows: "because I say it is." Thus was the Occidental aesthetic upset for all time... and noise music is but a continuation of that precedent.