Kenji Muto

Apparatus for automatically setting the optimum performance characteristics of a tape recorder

An apparatus using microcomputing system for automatically setting the optimum performance characteristics of a magnetic tape used. When the type of a magnetic tape loaded into a tape recorder is detected, the microcomputing system sets the standard recording level and the standard recording bias level of the magnetic tape in a recording level setting circuit and a bias level setting circuit of the tape recorder, respectively. When an automatic setting instruction and a subsequent recording start instruction are issued, a test signal having a certain frequency range is recorded on the magnetic tape and reproduced therefrom. The reproduced test signal is then supplied to a level deviation detecting circuit which detects the level deviation between the test signal of a predetermined frequency and the reproduced test signal of the same frequency and the level deviation between components of the reproduced test signal which are of different frequency. The microcomputing system corrects the standard recording level and the standard bias level to the optimum recording level and to the optimum bias level on the basis of the detected level deviations, respectively. An erase head to erase the test signal recorded is disposed at a position downstream of a playback head in the running direction of the magnetic tape, and the normal recording is started immediately after completing the automatic setting without rewinding the magnetic tape.

Sound source measurement of magnetic resonance imaging acoustical noise for feedforward active noise control system

We proposed the Active Noise Control (ANC) system reduce the loud MRI sound. It was important for performance improvement of the system. Therefore we estimated the sound source of MRI acoustical noise. The position of the sound source of MRI acoustical noise was between the center and the edge in the gantry of MRI equipment. MRI equipment is important for the medical inspection which gets the tomography of the body without X-ray. The patient of the MRI inspection needs to use the ear protector because the MRI equipment generated the loud sound which the sound pressure level was around 100dB. The study considers improvements to the acoustical environment when using the ANC system for MRI patient. The ANC system we developed is a feedforward system MRI acoustical noise is unsteady and pulsed. The system uses non-magnetic devices ear protectors, and optical microphones, because the MRI rooms are highly magnetic environments. We determined the sound source of MRI acoustical noise to set the reference micropho...

Data compression for transmission of holographic 3D images using digital SSTV

In this paper, the quality of recovered holographic images produced by CGH adopted JPEG2000 is investigated. As a result, it is observed that this process gives nice 3D reconstructed images. It appears to show that a transmission of 3D holographic images can be possible.

Acoustic communication system using bone conduction elements

This study examines an acoustic communication system constructed using a bone conduction speaker and a bone conduction microphone. This system is a headset that places a bone conduction speaker to the user’s cheek, and a bone conduction microphone to the other cheek. A user can thereby hear a voice through the bone conduction speaker while hearing a voice of a loudspeaker and surrounding noise when using it for teleconferencing. It can transmit the voice of the remote loudspeaker using the external ear, but the user can hear the translated voice through bone conduction. However, the sound of the bone conduction speaker and the surrounding sound are mixed with the speaker’s voice using the bone conduction microphone. The vibration level of the bone conduction microphone from the bone conduction speaker was about 0 dB, although it was the same level as the level of the speaker’s voice. The vibration level from surrounding sound was about −3 dB, although it was a smaller level than the level of the speaker’s...

An Investigation on the Plant Modeling Filter's Parameters for Active Noise Control System

Usually an FIR filter is used to model the physical paths in an active noise control system. However, the order of the filter to be modeled is a key factor for determining the computational load for the adaptive algorithms associated with active noise control (ANC), particularly for multi-channel algorithms. In this letter, the relationships among the filters order, the plant modeling error and the location of poles for the transfer functions of the physical paths in an ANC system are theoretically examined and numerical examples are given to verify the theoretical results.

Broadcasting technique for holographic 3D moving-picture utilizing network streaming

Recently, because the high-speed network system known as broadband internet has become widespread, it is now possible to transmit various forms of mulitmedia data using this system. We found several research reports for the transmitting visual images in the network streaming process. However, there seemed to be few reports on transmission of holographic 3D movies. We present a transmitting process of holographic 3D movies adopting network-streaming techniques and a hologram in which 3D objects were recorded as fringe patterns. When we applied this method, we could achieve excellent transmission of holographic 3D movies. Moreover, we could reconstruct good holographic images using transmitted streaming data. From this result, it seemed possible to develop new transmitting processes of 3D moving data using well-known conventional techniques.

A trial experiment of distance learning with the links of satellite communications, ISDN and the Internet

As communication media for distance learning, satellite communications, ISDN and the Internet are generally used, we have held experiments on the distribution of events with these media. These experiments have three features. First, we connected two satellite communication systems. Second, we received a distribution of an event with two kinds of links, a satellite link and an ISDN link, and compared the quality of distributed picture and sound. Last, we received a distribution of an event with two Internet video distributions application by two kinds of links, the Internet and ISDN, and compared the quality of distributed picture and sound. From the experience of these experiments on distribution, we show some prospects about distance learning in the case of these media.

Relation between area of shielding bone-conduction microphone and quality of speech communication in noisy environment

The doctor does not receive the transmitted voice of the patient when the patient becomes unwell in MRI examination, because the voice is faint and MRI acoustical noise is loud. Our purpose is to improve the quality of speech communication of bone-conduction microphone to transmit the patients faint voice to the doctor. We propose the theoretical formula using the characteristic of vibration propagation for calculating the quality in the case of the shielding microphone. In this report, the improvement level of speech communication quality in the case of the shielding microphone is estimated by the proposed formula in order to discuss the accuracy of the proposed formula. Here, the improvement level of shielding was calculated with a phantom. The phantom consists of a ceramic plate and a silicon rubber representing bones and muscles, respectively. The vibration of vertical direction on the phantom was measured with accelerometers to calculate the improvement level. The results showed that the quality of ...

Influence of visual information presentation method and sound presentation method on subjective evaluation of boat traffic noise

Information on the acoustic environment such as the engine noise of cruising boat on the canal is necessary for town planning. Miyagawa has investigated the influence of the visual of a sound source on an impression of the sound. The study has evaluated the shift on the impression of the sound by the visual stimulus. We focus on human subjective evaluation of the noise stimulus of moving source in this study. Our objective is to clarity the influence of visual information on the subjective evaluation of one moving boat noise. In this experiment, we examined the subjective evaluation of the moving source comparison between the stimulus of the sound and the stimulus of the sound and visual in the case of moving boat noise. This experiment used a 24-inch monitor, a headphone, or loudspeakers. The sound pressure level of 42–70 dB. As the result, the value of subjective evaluation was decreased by the moving source of loud boat noise, in the case of visual information of the moving boat.

Relation between Image Detection Time and Thumbnail Image Size for Satellite-based Telemedicine☆

Abstract We considered a support system for medical image-based diagnosis over satellite communication which can be used by doctors in a remote disaster area who have little experience of the system. Quick image-based diagnosis is difficult to perform using satellite since satellite communication lines are characterized by long delays and low transmission speeds. Therefore, it is necessary to design a visual interface that enables inexperienced doctors to work quickly and accurately. The purpose is to clarify the characteristics of thumbnails for images selection quickly for a support system of medical image-based diagnosis over satellite communication. The relation between the size of thumbnail image and the detection time of desired image in low speed network was investigated for the accomplishment of the purpose. We proposed an experimental method for clarification of the thumbnail image size for the selection of a desired image from among many images. We analyzed the time in which the subjects were able to find a desired image from among 10 images. The relation between detection time and thumbnail size had a minimum because satellite communication is associated with a long delay. Our experiment showed that the optimal size if thumbnails for fast image transmission can be calculated based on the shortest image detection time.