Masafumi Matsumura

Nonrestrictive and long‐term monitoring system of utterance and a laughing voice: Laughometer

It is said that laughter is the best medicine. Laughter is known to be effective for relieving stress and promoting health. Therefore, this study is intended to clarify the relationship between laughter and physiological factors related to health promotion. We developed a hands‐free wireless system (Laughometer) that monitors laughter (a laughing voice) in everyday conversations. This Laughometer detects vocal cord vibrations using a bone‐conductive microphone attached to the skin on the neck. Based on data from repeated vocalizations of laughter, this apparatus can distinguish features of laughter in everyday conversations. Based on the mean fluctuation (standard deviation) in syllable intervals, 90% of laughs are differentiable from normal conversation. While attending a live rakugo comedy show, the number and duration of laughs were monitored by analyzing laryngeal voice (approximately 1‐h duration). The mean differentiation rate for laughing voice was 94%, thereby confirming the efficacy of laughter recognition based on fluctuation in syllable intervals.

Accurate measurement of three‐dimensional shapes of a vocal tract and a dental crown using magnetic resonance imaging: Japanese fricative consonants

Three‐dimensional MR images of the vocal tract of three adult males were obtained during steady‐state production of the Japanese fricatives /s/, /sh/, and /shu/. MR images of dental crowns containing a small amount of water were obtained using a dental crown plate which was shaped so as to attach tightly to the subject’s dental crown by thermoforming which contained a contrast medium for MR imaging. A computer algorithm based on gray level interpolation and threshold operation for air–tissue boundary tracing of arbitrary sections of the vocal tract taken from axial and coronal MR images were proposed. Images of arbitrary sections of the vocal tract were reconstructed from 3‐D MR images using gray level interpolation based on the sampling theorem. Gray level thresholds were computed from the gray levels at points on the air–tissue border. The boundary tracing error of the dental crowns from the 3‐D MR images was less than 5.7%. The 3‐D shape and area function of the vocal tract during production of the Jap...

Measurement of palatolingual contact stresses and patterns during consonant production using a force‐sensor‐mounted palatal plate

In this paper the measurement of palatolingual contact stresses and patterns during consonant production using a force‐sensor‐mounted palatal plate is reported. The force sensor is composed of a strain gauge and a cantilever mounted on a palatal plate which is attached to a hard palate. The palatolingual contact stress is concentrated at one spot on the cantilever by a protuberance bonded on to the cantilever. When the tongue touches the force sensor, the palatolingual contact stress is detected as the strain in the cantilever. A prototype system was developed consisting of a 16‐force‐sensor‐mounted palatal plate (thickness=1 mm) and a multichannel strainmeter. The output of the force sensor was proportional to the stress applied to the cantilever and had no hysteresis. Error due to mechanical interference among the sensors was less than 5.4%. The palatolingual contact stresses and patterns for an adult male were measured during production of the consonants /t/, /d/, and /n/ using the present system.

Tongue-shaped measurement using piezoelectric thin film

A tongue-shaped measuring system was developed using a polymer piezoelectric film to analyze the tongue motion in harmonization of utterance. The copolymer piezoelectric film has a bimorph structure and produces a voltage proportional to the curvature of the tongue. By attaching the film on the tongue, the curvature at each point on the surface is measured, and the shape of the tongue is calculated from the curvature. To evaluate the shape measurement using the developed system, a simulator for the tongue shape was constructed, which has a curved surface of curvature between −0.4 to −0.57 cm−1. The shape of the simulator was measured. It was verified as a result that the error of estimation along the normal direction of the surface is within 0.5 mm, which is sufficient for the measurement of the tongue shape. Then the developed system was applied to measure the shape of the median and the frontal shape of the tongue during utterance. It is shown that the shape of the tongue during utterance can be measured. In the case of median shape, the curving. process from the main part to the tongue tip during the utterance of /r/ was clearly measured. The frontal shape, which has been difficult to measure, can easily be measured as in the case of the median shape, by modifying the placement of the copolymer piezoelectric film. The concave shape on the median line of the tongue during vowel harmonization was observed clearly.

Artificial speech production device for laryngectomees controlled by jaw and tongue movements

The purpose of this study is to develop an artificial speech production device for laryngectomees. The device is composed of three parts, a measurement part for jaw and tongue movements, an estimation part for the formant frequencies, and a voice synthesizer. This paper argues that the formant frequencies of vowels can be estimated from tongue and jaw movements of the subject, and that based on this information, continuous vowels can be produced using a voice synthesizer. Curvature of midsagittal tongue surface is measured with piezoelectric film. The degree of the jaw opening is estimated by the electrical impedence between right and left buccalis. Experimental results suggest that the formant frequencies can be determined from the curvature of the tongue surface and the jaw opening. Therefore, a mapping function is introduced to obtain the formant frequencies for the synthetic speech. The amplitude and pitch of the voice are controlled manually by the person who wears the device. The articulation score of the voice produced by the device was 95% for isolated vowels and 90% for connected vowels. Results showed the usefulness of the proposed device.The purpose of this study is to develop an artificial speech production device for laryngectomees. The device is composed of three parts, a measurement part for jaw and tongue movements, an estimation part for the formant frequencies, and a voice synthesizer. This paper argues that the formant frequencies of vowels can be estimated from tongue and jaw movements of the subject, and that based on this information, continuous vowels can be produced using a voice synthesizer. Curvature of midsagittal tongue surface is measured with piezoelectric film. The degree of the jaw opening is estimated by the electrical impedence between right and left buccalis. Experimental results suggest that the formant frequencies can be determined from the curvature of the tongue surface and the jaw opening. Therefore, a mapping function is introduced to obtain the formant frequencies for the synthetic speech. The amplitude and pitch of the voice are controlled manually by the person who wears the device. The articulation score ...