IMAGE: There was a loudspeaker embedded in a circuit that was attached to the hard pallet to create a semi-static sound field in the OC. The probe microphone was placed in the sound field … view more
Credit: Masashi Unoki from Japan Advanced Institute of Science and Technology
The perception of our own voice depends on the transmission of sound through air (directed by air) as well as through the skull (led by bones or BC). However, the transmission characteristics of BC speech are not understood. Now, scientists from Japan’s Institute of Advanced Science and Technology are reporting their latest findings on BC diffusion under the influence of oral cavity sound pressure, which could stimulate BC-based technology and basic research on loss. hearing and speech impediment.
Ever wonder why your voice feels different in recording compared to how you see it as you speak? You are not alone. The reason is related to the two types of transmission of our own voice, namely air-directed speech (AC) and bone-directed speech (BC). In terms of AC speech, the voice is transmitted through the air through lip radiation and contrast, but for BC speech, it is transmitted through the soft tissue and bone of the skull. That’s why when we hear ourselves in a recording, we only see AC speech, but while we talk, we hear both AC and BC speech. To understand, therefore, the relationship between speech production and comprehension, it is necessary to describe these two processes of speech production.
This is further confirmed by recent scientific studies showing that BC speech transmission affects the understanding of our own voice similar to AC speech transmission. However, the process of BC speech transmission is still misunderstood.
In a new study published in Journal of Speech, Language and Listening Research, a team of scientists from the Japan Institute for Advanced Science and Technology (JAIST) tried to understand the process of BC speech transmission by studying the vibrations of the regio temporalis (or RT, temple area of the head) and sound radiation in the ear canal (EC) caused by sound pressure in the oral cavity (OC). Professor Masashi Unoki of JAIST, who was involved in the study, describes their approach, “We adopted a transmission path model for BC speech in which it is accepted that sound pressure in the OC causes vibration of the soft tissue and bone of the skull to the outer ear. Based on this idea, we focused on how invitations in the OC would affect the transmission of BC to RT and the EC. ”
To measure BC transmission, the scientists selected five university students (three males and two females) aged 23-27 years with normal hearing and speaking ability. In each participant, they added a small loudspeaker to their hard pallet (the structure in front of the top of the mouth) and then sent them computer-generated excitation signals. The response signals were recorded simultaneously on the skin in their left RTs and right ECs with a BC microphone and a probe microphone, respectively. Each participant went through 10 measurement tests.
The team found, when analyzing the motion function (which models system frequency response), that the RT vibrations support all frequencies up to 1 KHz while the pressure of the EC boosts frequencies in the 2-3 KHz range. Combining this observation with an earlier report which showed that BC speech is considered “low pitch”, or under low frequency control, the team concluded that it is not the EC transmission, which cuts off both very low and very high frequencies, playing a major role in BC speech perception.
The findings have inspired scientists who anticipate several applications of BC diffusion in future technology. As Dr. Unoki points out, “Our findings can be used to develop BC – based headphones and hearing aids in the future as well as provide speech on BC microphones and speakers. currently employed with accessible devices.In addition, it can be used to analyze audio feedback in BC speech communication that influences basic research on hearing loss and speech disorders . “
Based on these promises, it seems that future technology could even help us to express ourselves better!
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About Japan Advanced Institute of Science and Technology, Japan
Founded in 1990 in the prefecture of Ishikawa, the Japan Institute of Advanced Science and Technology (JAIST) was the first independent national graduate school in Japan. Now, after 30 years of steady progress, JAIST has grown to become one of the top universities in Japan. JAIST counts with multiple satellite campuses and seeks to nurture capable leaders with a modern education system where diversity is essential; about 40% of its alumni are international students. The university has a unique style of graduate education based on a carefully designed coursework curriculum to ensure that its students have a strong foundation for further study. JAIST also works closely with both local and overseas communities by promoting collaborative business-academic research.
About Professor Masashi Unoki from Japan Advanced Institute of Science and Technology, Japan
Dr. Masashi Unoki is a Professor at the School of Information Science at Japan Advanced Institute of Science and Technology (JAIST) where he received his MS and Ph.D. degrees in 1996 and 1999, respectively. His main research interests in signal processing are driven by audibility and modeling of monitoring systems. Dr. Unoki received the Sato Award from the Japan Acoustical Association (ASJ) in 1999, 2010, and 2013 for the Yamashita Taro “Young Researcher” Special Paper and Award from the Yamashita Taro Research Foundation in 2005. He has published 198 papers and he has written 14 books to date.
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