The manipulator has two-degree-of-freedom of rotation and gripping, and is capable of ensuring force feedback or force sensation with excellent operationability. In another aspect, the invention generates a reduced-information representation of an audio signal by dividing an audio signal into auditory events, each of which tends to be perceived as separate and distinct, and formatting and storing information relating to the auditory events. The support arm includes an upper arm portion and a lower arm portion. Subject matter creators rate the quality of individual pieces of material, while concurrently being reviewed themselves to assess the level of expertise of each reviewer, and thus, the degree of weight that should be given to the commentary of each reviewer.