Correction Method of Estimated Distance Using Geometrical Information on Sound Source and Microphone

In many engineering fields, distance to target is very important and fundamental information. Acoustical signal often plays an essential role in measurement of distance. Though there are distance measurement methods using a time delay between transmitted and reflected waves, it is difficult to measure short distance because the transmitted wave suppresses the reflected waves for short distance. Recently, in a research field of microwave, a method for measuring the short distance has been proposed using interference (i.e., standing wave) of transmitted and reflected waves. We applied the fundamental principle of this method to the estimation of short distance using audible sound as a transmitted wave. Until now, this method supposed that microphone was set at the straight line between a sound source and a target. However, we can not estimate exactly the distance between the microphone and target when the microphone is not set on the straight line due to the restriction of measuring environment. This paper describes a principle and its correction method for the distance estimation when a microphone is not set on the straight line between the sound source and microphone. Then, we perform a computer simulation under the condition that audible sound is used as a transmitted wave. Finally, we experimentally confirm the validity and effectiveness of the method proposed by applying it to the distance estimation problem in an actual sound field.APSIPA ASC 2009: Asia-Pacific Signal and Information Processing Association, 2009 Annual Summit and Conference. 4-7 October 2009. Sapporo, Japan. Poster session: Audio and Electroacoustics (5 October 2009)

Fossil Rootless Fumaroles in the Noboribetsu Pumice Flow Deposits and Their Alteration Products in the Noboribetsu Formation, Kuttara Volcano, Southwestern Hokkaido, Japan

Many fossil rootless fumaroles are found in the upper unwelded facies of the Noboribetsu Pumice Flow Deposits, which are distributed around the Kuttara Caldera, SW Hokkaido. Rootless crater pits immediately above the fumaroles are filled by pumice, scoria, ash, and mud of the Noboribetsu Formation overlying the Noboribetsu Pumice Flow Deposits. Alteration due to the fumarolic action clearly extends into the Noboribetsu Formation. The origin of the Noboribetsu Formation is suggested to be a base surge deposit based on its distribution and lithological characteristics