*2.1. Voice Behavior*

The concept of voice was first proposed by Hirchman in the field of economics. It has been further developed in the field of organizational behavior [19]. Currently, voice behavior is divided into employee voice, customer voice, and public voice. Most research on voice behavior has been in the field of organizational behavior and mainly aimed to explain employee voice within organizations. Van dyne and Lepine define employee voice behavior as a positive extra-role behavior focused on improving existing working methods and procedures through constructive suggestions; they emphasize the 'promoting' role of employee voice for the organization [14]. Van dyne et al. further expand the concept, pointing out that voice includes not only suggestions for improvement, but also concerns about the organization [20]. On this basis, Liang et al. clearly divide voice behavior into promotive voice and prohibitive voice [21]. Promotive voice refers to innovative ideas or suggestions put forward by employees to improve the overall operation of the organization, while prohibitive voice refers to employees' attention to work practices, and events and employee behaviors that are not conducive to the development of the organization [21]. Employee voice is widely considered a valuable and positive extra-role interpersonal communication behavior, a kind of organizational citizenship behavior that plays an important role in the team and organization. Scholars have conducted in-depth research on the influential factors and outcome variables of employee voice. Previous studies indicate that personal characteristics, leadership, and organizational climate can influence employee voice, which will be beneficial to organizational betterment [2,3,22–29]. Additionally, the approaches of employee voice are also optimized due to the development of the Internet [30].

With the aggravation of market competition, customer participation becomes crucial for the product and service innovation of enterprises, and enterprises have created brand virtual communities to gather customers' ideas and opinions. Research on voice behavior has also expanded from the internal voice of the organization to the field of consumer behavior. On the connotation level, Gri ffi n and Hauser regard customer requirements as customer voice, holding the view that customers would sort their needs according to importance and convey them to enterprises [31]. Enterprises can then develop new products based on customer requirements. Lee et al. expand the connotation of customer voice and define it as a description of customers' needs and expectations or preferences and dislikes, including the pursuit of rights and interests, suggestions for new products and services, and complaints about previous use experience. Earlier definitions of customer voice are based on customer needs, but with advances in research on employee voice within organizations, scholars have begun to redefine customer voice from the perspective of role orientation. Ran and Zhou clearly define customer voice as the extra-role communication behavior in which customers actively make suggestions or express opinions to improve the status of enterprises; this kind of behavior belongs to the category of customer citizenship behavior [32]. At the dimension level, most previous studies on customer voice divide it into two categories: customer satisfaction and customer complaint [33]. With the deepening of research, scholars find that customers not only express dissatisfaction regarding product and service providers, but also express satisfaction and praise, and make their own suggestions. Therefore, with reference to the classification of employee voice by Liang et al., customer voice can be divided into promotive voice and prohibitive voice [21]. Promotive voice refers to the innovative ideas and suggestions of customers regarding improvements to the e fficiency of enterprises, while prohibitive voice refers to the expression of opinions on actual and potential problems within the products, services, or managemen<sup>t</sup> of an enterprise that are harmful to the enterprise or its customers. As the input behavior of customers

to enterprises, customer voice can urge enterprises to innovate products and services to meet the needs of customers, thus improving customer satisfaction and maintaining customer loyalty. It can also help enterprises correct errors, provide solutions to problems, and improve enterprise performance [33,34].

With the rapid development of social media, people can express their views on social issues more directly and conveniently, and research on voice behavior has been further extended to a broader social life context. Public voice behavior refers to citizens sharing opinions on social media to improve their social status quo or prevent harmful practices. It is essentially a pro-social behavior [4]. Public voice channels have begun to focus on social media, because in the modern world, social media presents extensive information; people express their concern about education, security, the environment, work-life balance, and many other issues online. Moreover, the diversity and openness of social media provides a broad platform for public expression. The public can conduct online voice behavior through third-party social media and public participation is increasing. However, research on public voice based on social media is still in its infancy and is uncommon. Bhatti et al. explore the mechanism of the e ffect of individual moral identity and proactive personality on public promotive voice and prohibitive voice based on self-consistency theory [4].

Research on voice behavior as discussed above has several characteristics. First, the research field has shifted from intra-organization to a broader social background. Second, the voice subjects present a change trend of 'employee-customer-public'. Third, the targets of voice behavior change from organizational practice to general social phenomena. Fourth, the form of voice presents the evolution trend of "face-to-face-virtual community-social media".

#### *2.2. Public Role in Public Policy*

Citizen participation in the formulation and consultation of public policies is an important way to strengthen and support modern democracy [35]. Regarding the influence of public participation on policy, most research reveals extensive interest in environmental protection and pollution control, as public participation can help decision makers recognize public concern and demands, and handle environmental conflict in a more flexible manner [36,37]. Fu and Geng explore the influence of public participation and regulation compliance on 'green development' with panel data from 30 provinces in China from 2004 to 2014, finding that public participation can lead enterprises to improve compliance and thus promote green development [8]. Regional environmental quality (REQ) is a comprehensive indicator of emissions of waste gas, waste water, and waste solids, and its improvement requires coordination between governance and public participation. Public participation can be coordinated with governance to e ffectively improve REQ e ffectively, and further promote the optimization of environmental governance system [38]. The arrival of the Internet era has changed the method of public participation. As a branch of e-government, e-participation has been widely examined by scholars. Considering that public participation is a voluntary activity, whether the public is willing to participate is the decisive factor a ffecting the success of e-governmen<sup>t</sup> platforms. Scholars consider that in addition to demographic di fferences, willingness to use an e-participation system is a ffected by system technical factors, personal incentive factors, and social capital factors. Based on the unified theory of acceptance and use of technology, planned behavior theory, social capital theory, and other information system theories, previous studies have explored the willingness of the public to use the e-community to participate in policy-making and provide strategic suggestions for governments to improve e-governmen<sup>t</sup> platform [39,40].

#### *2.3. Product Innovation*

Product innovation is an important focus in the innovation research field and is key for enterprises to obtain sustainable competitive advantage. At present, there is no unified definition of product innovation in academia. Katila and Ahuja define it as change in design attributes—such as technology, appearance, quality, and structure—relative to the existing products of an enterprise. This is also known as technological innovation or design innovation [41]. The Organization for Economic Co-operation and Development defines product innovation as the process leading to a new or significantly improved product or service [42]. Various scholars' definitions of product innovation, identify two aspects: entity product innovation and service-related innovation. According to the di fferent degree of innovation, product innovation can be divided into radical innovation and incremental innovation [43]. Rapid change in the external environment drives enterprise innovation; enterprises can only achieve long-term development by constantly producing more competitive products according to the needs of users. As an external innovation resource, customer voice can be regarded as a gift given by users to enterprises to help them carry out product innovation based on the collective wisdom [44–46]. Customer voice provides valuable information for enterprises, which can help product designers and engineers to understand customers' needs and preferences, and turn them into key objectives of product improvement by making targeted adjustments to products and services to meet the needs of users [47]. Further, customer voice can help enterprises identify the product attributes to which customers pay most attention and focus on product improvement and new product development [48].
