Hindawi Publishing Corporation International Journal of Distributed Sensor Networks Volume 2012, Article ID 314078, 13 pages doi:10.1155/2012/314078 Research Article Enabling Collaborative Musical Activities through Wireless Sensor Networks Santiago J. Barro, Tiago M. Fern ´ andez-Caram´ es, and Carlos J. Escudero Departamento de Electr´ onica y Sistemas, Universidade da Coru˜ na, 15071 A Coru˜ na, Spain Correspondence should be addressed to Carlos J. Escudero, escudero@udc.es Received 14 July 2011; Revised 9 December 2011; Accepted 10 December 2011 Academic Editor: Yuhang Yang Copyright © 2012 Santiago J. Barro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In professional audio production the setup of electronic musical devices is a time-consuming and error-prone process, as it involves manual operations like establishing local configurations and carrying cables for each device. Such is the case of MIDI (musical instrument digital interface), which is widely used in the context of musical applications. On the other hand, the capabilities of WSN (wireless sensor networks) allow developers to build up more complex applications, since nodes have the ability of autoidentifying, autoconfiguring, and establishing associations with other nodes, behaving in a smarter way than other networks. In this paper, we propose the use of an optimized WSN network for interconnecting MIDI devices. This network has been named collaborative musical wireless network (CMWN): it eases device configuration, enables musical collaboration, and allows artists to explore new ways of expression. The paper also presents the hardware and performance results of a prototype able to create CMWNs. 1. Introduction The field of professional audio production refers to all those activities in some way related with the processing of sound using electronic means [1], that is, musical performances, composition and arrangement [2], artistic performances, and multimedia spectacles [3]. Technology plays an impor- tant role in the world of professional audio production. Several types of device are involved, such as microphones to record voices and musical instruments, audio processors to apply special effects (echo, delay, etc.), and multitrack mixers to synchronize audio and video in soundtracks for documentaries and cinema, amongst others. The quality of the artistic results depends on the selection of the device settings, which is usually done by a technician with special skills in music and technology, either by using cables or software. Communication between musical devices is possible thanks to musical protocols, which can be classified into two categories: wave-oriented protocols and control-oriented protocols [4]. Wave-oriented protocols carry the sound data, either in analog or digital format, and contain all the information needed to play the sound. In contrast, control-oriented protocols are used to intercommunicate musical devices internally, usually to cause an action to be performed in response to the occurrence of an event. This is the case of the MIDI protocol, in which the information transmitted needs to be interpreted by a synthesizer before an audible waveform can be obtained [2]. The combination of both wave-oriented and control-oriented protocols allows artists to create a complete multimedia performance through the interaction of various multimedia nodes, which form a multimedia network. Control-oriented protocols have the advantage of being much easier to process because the musical events are explicit. For instance, with wave- oriented protocols a signal processing analysis algorithm like the one needed to detect sound frequency [5] can work incorrectly due to the presence of different musicians playing simultaneously in live concerts, as the harmonics of their instruments are mixed with the noise. However, control- oriented protocols like MIDI detect the sound immediately, simply by reading the corresponding value of a MIDI message.