By any standards, Neil Young's music is loud. So his recording studio in Santa Cruz needed to withstand noise and lots of it. The same was true of the Musician's Institute in Hollywood. To have even an inkling of a chance of keeping the neighbors happy, both installed Air Krete, which acts as a very effective sound barrier in addition to providing insulation. This is because sound waves depend on vibrations transmitted from air making anything in its path vibrate, which then transmits the vibration to sound waves on the other side and finally to our ears. And once it's dried, Air Krete is simply too rigid to vibrate.