A wheelchair security system comprises a wheelchair body fabricated of non-metallic material. The pocket can be constructed from multiple different sections joined with one another, or can be knitted, weaved or otherwise assembled on an automated assembly machine from strands, andor can be formed as a unitary textile material having regionssections with different physical andor mechanical properties. At a second stage, the method and system filter heart sound from the signal energy envelope by applying an adaptive filter that minimizes the loss of respiration sound. The end surface is typically flat in transverse direction between the inner and outer junction edges, and the outer end defines an outer end portion that is bent transversely inwardly. In one embodiment, the security system integrates multiple sensor systems for the detection and identification subterranean as well as terrestrial breach.