In this paper, we propose a density estimation system of user density at the closed space using high frequencies of speaker and microphone of smart device. High frequencies are sent to the closed space by the server speaker of the density estimation system, and smart devices located at the space detect the high frequencies via the microphone of each device. The smart devices detecting the high frequencies send data to the server system, and the system calculates data from the smart devices. To evaluate performance of the proposed system, we did some experiments with the density estimation system and 20 smart devices. According to the test results, the proposed system showed 96.5% accuracy, and we confirm that the system is very useful for density estimation. Therefore, this system can precisely estimate user density at the closed space, and it could be useful technology for the density estimation of space users and measurement of space using state at indoor space.

中文翻译：

---

使用扬声器高频率的空间用户密度估计系统

在本文中，我们提出了使用智能设备的扬声器和麦克风的高频在封闭空间内的用户密度的密度估计系统。密度估计系统的服务器扬声器将高频发送到封闭空间，位于该空间的智能设备通过每个设备的麦克风检测高频。检测到高频的智能设备会将数据发送到服务器系统，然后系统会从智能设备计算数据。为了评估所提出系统的性能，我们对密度估算系统和20个智能设备进行了一些实验。根据测试结果，提出的系统显示出96.5％的准确度，并且我们确认该系统对于密度估计非常有用。因此，该系统可以精确估算封闭空间的用户密度，