Oh gosh I know exactly what that noise is like. In my experience, Siamese are VERY heavy footed. The first Meezer/Domestic Short Hair cross that we had used to sound like this as she ran up and down the hallway at 6.a.m. on Saturday mornings:

"Thump, thump, thump, thump (add the Doppler effect here as she gets closer), THUMP, THUMP, THUMP, sound of claws getting stuck in the carpet, THUMP, THUMP, THUMP (add the Doppler effect here as she gets further away). Repeat about 1,345 times.