So famous is Nipper that his likeness is displayed in The Smithsonian. The above stained glass window once adorned the factory in Camden, NJ. He was on the label of RCA records for decades - save for that period in the 70's when they had that orange label. (In the UK, they never used Nipper after that period as the trademark was owned by HMV)
But.....Nipper is a fox terrier - a smooth one rather than a wire - but still a fox terrier. I have had many fox terriers. It's highly doubtful he was mesmerized by the sound of 'his master's voice.' Fox terriers don't care about their master's voice. They do, however, care deeply for vermin. A more believable scenario has to do with the surface noise on the old '78's. Nipper is probably thinking there's a mouse in there scratching away. Personally I'd get him away from the hi-fi. It's likely to turn into a pile of metal in the next few minutes.
I once had a foxy dismantle a woodpile single handedly because a critter ran underneath it. They've caught birds and squirrels. And they'd bring them in the house as gifts - well not gifts actually - they'd put them in front of you but quickly snatch 'em up and run when you tried to dispose of it. I had two at one time playing tug-of-war with a squirrel.
You get the picture. They're crazy - all of them.
Here's a typical reaction to something as commonplace as a sprinkler