## 1 Introduction  
With the recent evolution of Augmented Reality (AR) glasses, Computer-Supported Collaborative Work (CSCW) environments using AR for communication support between workers have led to its expanded use in the fields of industry [1] and education [2]. [PERSON] et al. [3] argue that, compared to fully immersive VR environments, the application of AR environments to CSCW interfaces has the following advantages, i.e., (1) users of the system can work with each other's facial expressions, gestures, and body language, enriching the means of communication between users by providing a natural channel for communication, (2) users can manipulate the virtual image using familiar real-world tools to enhance the intuitiveness of the interface, (3) users can view the virtual object while simultaneously referring to the actual object, and (4) since there is no need to model the entire environment, a fast information and communication environment is established. The motivation of our research is to introduce an AR-based CSCW environment to support communication between surgeons during endoscopic surgery in the operating room. Endoscopic surgery is a safe and non-invasive surgical procedure that has been used successfully in many cases and it has developed rapidly as an alternative to conventional open surgery [4]. The research focused on its variety of tools and techniques [5]. In general,endoscopic surgery consists of two surgeons who communicate with each other about the surgical site and the procedure while looking at a monitor on which images taken by the endoscope are projected. However, the surgeons usually grasp the endoscopic devices through access ports towards the body's interior tissues and proceed with the operation while maintaining the surgical field, and they cannot take their hands off the devices unless there is a severe problem. This treatment is vital for safe surgery to maximize continuous tactile perception, which can only be obtained indirectly through gloves and devices [6]. Additionally, time is lost due to the surgical field's collapse if the hand is released. In such a situation, both parties communicate cautiously about the surgical field's state obtained from the monitor and proceed with the operation. When requiring communication regarding the operation's detailed strategy, it is impossible to specify the image of the inside of the body projected on the monitor due to both hands being assigned to the devices. This problem makes it difficult for accurate and effective communication between surgeons, inducing disruptions of surgical workflow, which increases the duration of surgery and cost [7; 8; 9], and the development of the potential risk of medical accidents. The development of a hands-free communication device between operators in such an environment has been attempted in the past [10; 11; 12; 13; 14; 15; 16; 17; 18]. [PERSON] et al. [14] developed a communication support device called WHaSP (Wireless hands-free surgical pointer), which is equipped with a 6-axis acceleration sensor and Bluetooth device in the headset. The device has remarkably improved usability. Using this device, they conducted communication tests in an operating room environment with more than 100 cases. The results showed that the developed device significantly reduced the chances of the supervisor taking his hands off the surgical tools and pointing at the screen and significantly reduced the cases of abandoning the sterile barrier, compared to the surgical operation without the device. Ease of use is a key element in the functionality of a hands-free communication device. [PERSON] et al. [12] stated that in collaborative tasks using AR systems, it is more important to reduce the cognitive load among operators by having a simple annotation function, i.e., a function to show a trend with less precise lines, rather than to support precise drawing of information by head movements.