  Hitherto acoustic cloaking devices, which conceal objects externally, have
depended on the objects' characteristics. Despite previous works, we design
cloaking device placed neighbor an arbitrary object and makes it invisible
without the need to make it enclosed. Applying sequential linear coordinate
transformations, leads to a non-closed acoustic cloak (NCAC) with homogeneous
materials that creates an open invisible region. We propose a non-closed carpet
cloak to conceal objects on a reflecting plane. Numerical simulations verify
the cloaking effect, which is completely independent of the geometry and
material properties of the hidden object. Due to the simple acoustic
constitutive parameters of presented structures, this work paves the way toward
realization of non-closed acoustic devices, which could find applications in
air born sound manipulation and underwater demands.
