# Voice Communication Systems Impact on Navigating Officers
## 1 Introduction  
The International Maritime Organization (IMO) has adopted a number of regulations and guidelines related to ergonomics and ways of presenting information on a ship's bridge. However, the continuous development and introduction of new technologies has shown the problem of an overwhelming amount of information presented to the officer of the watch (OOW). Complex control systems where information is displayed in many different forms (digitally and analogously, visually and audibly) and with several independent communication systems may significantly increase the workload of a responsible person, whether it is on a ship's bridge [1; 2; 3; 4; 5] or some other industrial control systems [6]. This situation is emphasized on board by poorly designed systems or by no centralized information management systems [7]. In case of excessive amount of information, which an OOW needs to handle cognitively during a short period, the OOW may become overloaded and lose situational awareness of navigational circumstances. The workload may also increase and the situational awareness decrease if the attention of the OOW is interrupted or if they are distracted during the execution of a certain demanding task [8; 9]. The main causes of interruptions, i.e., distractions, are usually personal presence and crew member' conversations on the bridge, different system alerts and incoming calls through available communication systems. In general, low level of situational awareness may lead to human error or inappropriate decision-making [10], i.e., to a deviation from a known procedure of actions for which the OOW has been trained [11]. Most accidents at sea have involved human error to at least some degree [12; 13; 14]. The incoming calls through available communication systems on the ship's bridge are identified as one of the important distracting elements influencing an OOW [15; 16; 17]. The incoming calls, as well as notification of different systems' alerts, demand the immediate attention of the OOW, i.e., in the moment of occurrence, without \"choosing\" a suitable moment. It is important to emphasize that besides these mentioned important researches on the matter, and other researches on the workload in maritime industry, the authors could not find any recent scientific papers dealing with the influence of shipboard voice communication systems on the duty officers' performance. For the purpose of this research, the communication may be defined as any exchange of information between the OOW on a bridge and one or more other persons. In general, the communication may be divided into verbal and written. The incoming written messages are either received silently (e.g., e-mails) or followed by a respective sound alert if classified as a caution, warning or alarm [18; 19]. However, after acknowledging the alert and recognizing its priority and nature, the OOW may choose whether to read the message and act upon it immediately or at a more convenient time. On the other hand, voice calls in the moment of occurrence are either taken or not, which may distract the OOW more than a signal for a written message. Hence, only the incoming voice calls were considered for this research. Furthermore, for the purpose of this research, the incoming voice communication may be divided into higher priority calls (related to ship's safety and navigation) and lower priority calls (all other ship's business), i.e., potentially distracting calls. The communication systems, which are considered to be sources of potential distracting voice calls, are a ship's satellite telephone, a ship's mobile telephone, a ship's internal fixed telephone system and an internal Ultra High Frequency (UHF) radio. Therefore, Very High Frequency (VHF) radio voice communication was not considered for the research. The main research questions are:  
(1) To what extent does the voice communication on a navigational bridge influence the workload of an OOW during navigation? (2) In which manner may distractions activated by incoming voice calls be reduced?