Data are collected before and after percutaneous transluminal angiography (PTA) for dialysis patients.

Each sample is labeled as a-b-before.wav or a-b-after.wav and the associated txt, where a is the patient id and b is the location id.

The first position was the arterial-venous junction,  and the second point was 3 cm from the first position along the vein.

 The distances between the adjacent positions were also about 3 cm.