= Insulation/ Vacuum Wistling Noise =

 * Problem: Added long 10m flexible hose to my shop vac to clean inside ceiling. When connected it created a loud whistling noise.

 * Cause: even coronation of flexable hose.

 * Solutions:
   1. Buy a smooth hose :(
   2. Special pipe with irregular corrugations used in gas lines.
   3. :) modifying the hose with a heat gun to make corrugations less even. 
     * https://woodweb.com/knowledge_base/Dust_Collection_Hose_Whine.html