| Abstract: | We propose ‘Ubiquitous Acoustic Spaces,’ where each sound source can emit some address information and automatically enable us to access its related cyber space, using mobile terminals. This will be used for a new type of wireless advertisement for mobile phones using sound media. In order to realize this, we have proposed a nearly lossless audio watermarking technique, utilizing two‐channel stereo audio characteristics. This enables contactless asynchronous detection of embedded watermarks through loudspeaker and microphone devices even by using cell phones. We extend the embedding frequency band width and improve the extraction precision. Thus we enable watermark extraction from both stereo channels. Possible embedding data rate can be extended to 80 bps, and almost 100% data can be extracted in case of using PC or PDA devices as terminals. Moreover, we can carry out the watermark extraction even from cell phone loudspeakers or through public telephone networks. From our experiments, almost 100% extraction of 20 bps embedded data could be achieved with these phone devices. In this paper, we describe briefly our newly proposed dual monaural watermark embedding algorithms, and present a prototype system of ubiquitous acoustic spaces using cell phones, based on our experimental results of extraction precision on several capture signal conditions including experiments using cell phones or public telephone networks. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. |
