Strategic Young Researcher Overseas Visits Programfor Accelerating Brain Circulation 2011
“Development of Young Researchers
Based on International Joint Research
on Green Energy Systems”
Progress Report

1. Name: Kotaro Sonoda
2. Title: Assistant Professor

3. Host Institution: Adam Mickiewicz University (Poland)

4. Host Researcher: Professor Alexander Sek

5. Duration: 27- March -2012 – 27- March- 2013

6. Research Topic:
Applied diagnosis based on audible sound enrichment that realize
the measurement and control for high efficient energy systems
7. Overview of the Results of the Collaborative Research:
In recent years, a mechanism that controls the system intelligently by using
information of the various data shared on the system network has been practiced. New
power grid systems (smart grid), and electric vehicles are good representatives oftargeting of energy saving and high efficiency. At the same time, we also need toconsider the cooperation with equipment that is not connected to the information
network. In other words, it is required to have a variety of the means of conveying
information of the equipment condition to the network.
In this study, we aim to convey additional information to the receiver by embedding
watermark into the sound wave that is emitted from the system. The embedded
information is extracted by decoding the received sound wave. Here, it is important tokeep the sound wave robust against deterioration during its propagation in air.
Furthermore, it is preferable that the quality of the produced watermarked sound is not
significantly deteriorated from the original one.
Prof. Sek has studied the detection limits of human discrimination against modulated
sound. During my stay at AMU, I developed new digital watermarking method based on
the sound modulation and carried out some listening experiments with Professor Sek`s
support and suggestions.
We proposed a new digital watermarking method that is embedded by re-quantizing
the distribution of the time varying sound magnitudes in accordance with watermark
message bit. In this method, observing the time-varying magnitudes of the several
components on the short-term Fourier spectrum, the relation of selected four bins of thehistogram on the magnitudes have been changed. Here, the targeted frequency
components are not selected from an equally spaced scale, rather they are selectedfrom the scale of nERBs (Equivalent Rectangular Bandwidth). The nERBs arelogarithmic scale according to the frequency resolution of human hearing.

Figure 1: Proposed watermarking method
The robustness test against typical signal manipulations or attacks showed very good
performance of the proposed method. Subjective listening tests have also been carriedout to assess the quality of the watermarked signal, i.e. audibility of distortions resulting
from watermark. The results show that the proposed watermarking technique resists theMP3 compression attacks in the case of embedding payload below 2 kHz. However, theproposed procedure performs slightly poorer against the attacks of noise addition, band
pass filtering and echo addition. Results of hearing tests showed that the proposed
method doesn’t produce audible deteriorations. Finally, multi-band embedding wasinvestigated. Results showed that the multi-band embedding can embed up to 20 bits
without decrease in robustness against MP3.
For the future work, the countermeasure to increase robustness against noise andecho addition, band pass filtering, pitch modification are strongly desired.

8. Deployment Plans for Future Collaborative Research:

We, Prof. Sek and I, have been researching the improvement of the above proposedwatermarking method, and plan to publish them.
A watermarking method for the musical signal has been proposed and tested during mystat. As the next step, we will try to embed the watermark into the sound wave which isemitted from the mechanical systems.

9. List of Collaborative Research Progress:
Conference Presentation(s)●●[1] Kotaro Sonoda ``Content based audio watermarking in DWT domain,'' Openseminar on Acoustics (OSA2012), 2012
[2] Kotaro Sonoda, Alexander Sek, ``Digital watermarking method based on STFT
histogram,'' International Conference on Intelligent Information Hiding andMultimedia Signal Processing (IIHMSP2013), 2013