Improvement and Evaluation of Time-Spread Echo Hiding Technology for Long-Distance Voice Evacuation Systems
Several improvements to the time-spread echo hiding method are proposed for an aerial audio data hiding in which speech signals are broadcast by the outdoor loudspeakers of a voice evacuation and mass notification system. Evaluations of the data hiding system for speech signals were conducted using computer simulations including several disturbances caused by the long-distance (from 70 to 800 m) aerial transmission of sounds. The frequency response of a distant horn-array loudspeaker system, the absorption of sound by the atmosphere, reverberation and a single long-path echo, a constant frequency shift that mimics a small Doppler shift and a mismatch of sampling frequencies between sending and receiving devices, and additive background noise are simulated as disturbances. A background noise recorded outdoors was mixed to simulate a loud outdoor space in a city at signal-to-noise ratios of −5, 0, and 5 dB. The computer simulation results showed that the suppression of high- and low-frequency regions in the logarithmic spectral domain in the decoding process was significantly effective for the decoding performance. A novel hiding method of the alternating sign of echoes was moderately effective under relatively high SNR (0 and 5 dB) conditions.
KeywordsBilateral symmetric time-spread echo Frequency response Absorption by the atmosphere Reverberation Long-path echo
This study was partially supported by TOA Corporation. The author thanks the anonymous reviewers for their helpful comments and suggestions on this manuscript.
- 1.Cho, K., Choi, J., Jin, Y.G., Kim, N.S.: Quality enhancement of audio watermarking for data transmission in aerial space based on segmental SNR adjustment. In: Proceedings of IIHMSP 2012, pp. 122–125 (2012)Google Scholar
- 2.Chou, S.A., Hsieh, S.F.: An echo-hiding watermarking technique based on bilateral symmetric time spread kernel. In: Proceedings of ICASSP 2006 III, pp. 1100–1103 (2006)Google Scholar
- 3.TOA Corp.: TOA horn array speaker HA-450H (2014). http://www.toaelectronics.com/media/specs/ha450h_sa1e.pdf
- 10.Munekata, T., Yamatuchi, T., Handa, H., Nishimura, R., Suzuki, Y.: A portable acoustic caption decoder using IH technique for enhancing lives of the people who are deaf or hard-of-hearing – system configuration and robustness for airborne sound. In: Proceedings of IIHMSP 2007, pp. 406–409 (2007)Google Scholar
- 11.Nishimura, A.: Presentation of information synchronized with the audio signal reproduced by loudspeakers using an AM-based watermark. In: Proceedings of the 3rd International Conference on Intelligent Information Hiding and Multimedia Signal Processing, vol. 2, pp. 275–278. IEEE (2007)Google Scholar
- 12.Nishimura, A.: Aerial acoustic modem that is suitable to decode using a CELP-based speech encoder. In: Proceedings of IIHMSP 2010, pp. 514–517 (2010)Google Scholar
- 13.Nishimura, A.: Audio data hiding that is robust with respect to aerial transmission and speech codecs. Int. J. Innov. Comput. Inf. Control 6(3), 1389–1400 (2010)Google Scholar
- 14.Nishimura, A.: Simulation of long-distance aerial transmissions for robust audio data hiding. In: Proceedings of the 13th International Conference on Intelligent Information Hiding and Multimedia Signal Processing. Springer, Heidelberg (2017, in press)Google Scholar
- 16.Tetsuya, K., Akihiro, O., Udaya, P.: Properties of an emergency broadcasting system based on audio data hiding. In: Proceedings of IIHMSP 2015, pp. 142–145 (2015)Google Scholar
- 17.Tetsuya, K., Kan, K., Udaya, P.: A disaster prevention broadcasting based on audio data hiding technology. In: Proceedings of Joint 8th International Conference on Soft Computing and Intelligent Systems and 17th International Symposium on Advanced Intelligent Systems, pp. 373–376 (2016)Google Scholar
- 18.Thiemann, J., Ito, N., Vincent, E.: DEMAND: diverse environments multichannel acoustic noise database (2013). http://parole.loria.fr/DEMAND/