Method of estimating contact force of bone-conducted sound transducer with a two-degrees-of-freedom vibrating model

Abstract

In this paper, we propose a method of estimating the contact force of a bone-conducted sound transducer with a two-degrees-of-freedom vibrating model. First, the electrical impedance of the transducer was measured by varying the contact force applied to 12 human subjects. The model was fit to the measurement electrical impedance by changing the damping coefficient. The results showed that the model's damping coefficient is related to the contact force. The fitting was valid when the contact force was below than 3.0 N. Second, a contact force estimation method utilizing the relationship between the damping coefficient and the contact force was proposed. The contact force was estimated by estimating the damping coefficient from the measured impedance and calculating the corresponding contact force from the damping-contact force curve. The estimation results showed that the proposed method achieves reasonable accuracy compared to a previous method using a neural network. Also, the proposed method can be achieved with only two calibration conditions, 0.3 N and 0.5 N, by employing a physical model. This drastically reduces the calibration process compared to the previous methods.

Arrangement design for horizontally omnidirectional audible sound source using facing ultrasonic transducer arrays

“…Sound sources with omnidirectional characteristics have been studied for a long time and used for various purposes, such as loudspeakers for indoor voice announcements or measuring room acoustic characteristics. [1][2][3] In addition, ultrasonic transducers have been studied and implemented in a wide range of applications, such as ultrasonic sensors and parametric array speakers [4][5][6][7][8][9][10] with sharp directivity [11][12][13][14][15][16][17] owing to their flexible installation given by their size and structure. [18][19][20][21][22][23][24] In a previous study, we investigated an omnidirectional sound source using an ultrasonic transducer array.…”

Development of omnidirectional audible sound source using facing ultrasonic transducer arrays driven at different frequencies

“…[1][2][3] On the other hand, ultrasonic transducers have been widely studied for acoustic sensing transmitters/receivers and array parametric loudspeakers. [4][5][6][7][8][9][10] In research using parametric loudspeakers, several studies have been performed on the control of directivity and the sound field in a specific region. [11][12][13][14][15] Ultrasonic transducers are expected to be used in a variety of applications owing to their flexible installation given their size and lightness.…”