# The Impact of an Agent's Voice in Psychological Counseling: Session Evaluation and Counselor Rating
## 2 Literature Review
### Voice Cue  
Voice provides information about the speaker, such as age, gender, and identity [40]. It not only delivers characteristics of the speaker, including gender and personality, to the listener but also makes the listener imagine the appearance of the speaker merely by hearing the voice for the first time [41]. As people develop, they can discover highly relevant clues in terms of social aspects by considering the voice characteristics of speakers, inferring gender, personality, and emotions of speakers accordingly. Voice also conveys message through adjusting its duration, changing the height of the pitch and/or altering loudness. [PERSON] [42] found that a fast speaking rate, when compared to a slow speaking rate, is perceived to be more persuasive, and raises positive impression on the level of competence and social attractiveness of the speaker. [PERSON] and [PERSON] [43] also addressed that a message is perceived to be more persuasive when delivered at a faster speaking rate rather than a slower speaking rate.  
Moreover, people grant humanistic characteristics to computers that speak with voice and communicate with these computers as if they are interacting with other people [7]. Previous studies on voice-based interfaces found that voice characteristics exerted various effects on people. [PERSON], [PERSON], and [PERSON] [44] reported that the advantages of a conversation based on voice instead of text disappeared when the quality of the voice of the agent did not maintain that of the human voice in online learning environments. [PERSON] and [PERSON] [45] mentioned that the agent that performed conversations with human voice in online shopping environments had significant effects on the perception of users toward the social presence of the agent and that such voice-based conversation increased the level of their intention of using the agent to make purchase decisions.  
In HRI, defined as \"the study of humans, robots, and the ways they influence each other\" [46], social and cognitive interactions between a human and a robot is an essential factor [47]. However, most existing HRI studies concentrated on visual aspects of machines, such as appearances and designs, whereas research on the voice of machines received less attention [48]. A study found that the effects of the voice of machines varied depending on gender stereotypes of people. For example, computers using a male voice for conversations exerted more significant effects on the decisions of users than computers using a female voice. In addition, people were more likely to conform when the gender of computers was consistent with their own gender [49]. [PERSON] [50] granted gender characteristics to the voice of a robot through simple manipulation in an experiment and verified that the behaviors and emotions of people significantly varied according to the application of gender characteristics in the voice of the robot. [PERSON] [51] conducted extended research on the voice in HRI by applying the social identity theory. Older students in the research rated reliability and social presence of an AI system with an older voice much highly than younger students. Thus, people recognize computers and agents as social entities and become significantly affected by their voice characteristics. Particularly, people automatically infer traits of the agent based on its voice and such inferred traits of the agent affect the attitude and contents of the conversation between the agent and its users [17; 18; 19; 20]. The following section reviews the role of the counselor in a psychological counseling and what influence the perception of the counselee on the counselor exerts on the outcome of the counseling.