# Protecting Sensitive Data in the Information Age: State of the Art and Future Prospects
## 2 Analysis of Modern-Day Smart Services
### Voice-Controlled Digital Assistants  
In addition, the increasingly popular _Voice-Controlled Digital Assistants_ (_VDA_) depend on comprehensive data refinement and subsequent data processing. VDA refers to any hardware and software infrastructure that enables users to request information or give instructions by means of human speech. In addition to IoT devices that serve as microphones and speakers, a software agent is required that permanently listens for a predefined keyword. As soon as this keyword is received, the agent wakes up and records everything that is subsequently spoken. A speech analysis is then performed on the recordings, to interpret the spoken commands semantically and process them logically. Depending on the command, either speech synthesis is used to formulate a response or a machine-processable command is sent to a corresponding IoT-capable device [61]. The most popular VDA are _Alexa_ (see [[https://alexa.amazon.com/](https://alexa.amazon.com/)]([https://alexa.amazon.com/](https://alexa.amazon.com/)), accessed on 30 August 2022), _Siri_ (see [[https://www.apple.com/siri/](https://www.apple.com/siri/)]([https://www.apple.com/siri/](https://www.apple.com/siri/)), accessed on 30 August 2022), _Cortana_ (see [[https://www.microsoft.com/en-us/cortana/](https://www.microsoft.com/en-us/cortana/)]([https://www.microsoft.com/en-us/cortana/](https://www.microsoft.com/en-us/cortana/)), accessed on 30 August 2022), and _Google Assistant_ (see [[https://assistant.google.com/](https://assistant.google.com/)]([https://assistant.google.com/](https://assistant.google.com/)), accessed on 30 August 2022) [62]. Such VDA offer users a variety of benefits: First, the easy accessibility via the voice interface provides a convenient way to give tasks to the VDA. Second, this type of interaction also satisfies a hedonistic desire, as the user has command over a (virtual) assistant that can perform any assigned task. This is further amplified by the fact that the possession of such \"future technology\" also has a symbolic value, since its usage has a favorable impression on others. Third, VDA also have a positive social aspect, as natural language communication with them overcomes many impediments regarding the perception of the technology--the VDA is rather perceived as a person than a technical object [63]. Due to this variety of benefits, it is therefore not surprising that the popularity and demand for such VDA is growing constantly. This is further enhanced by the fact that more and more IoT devices are compatible with VDA, i.e., everyday objects can be used as input device and can be operated by a VDA. So, the VDA is virtually available at any time and any place [64]. The schematic architecture of the VDA ecosystem is outlined in Figure 3. A compatible input client with a microphone is required on the user side. The software agent of the respective VDA service runs on this client. This can be a conventional personal computer with Internet access, a smart device such as a smartphone, or a dedicated VDA-enabled device such as _Amazon Echo_ (see [[https://www.amazon.com/smart-home-devices/b?node=9818047011](https://www.amazon.com/smart-home-devices/b?node=9818047011)]([https://www.amazon.com/smart-home-devices/b?node=9818047011](https://www.amazon.com/smart-home-devices/b?node=9818047011)), accessed on 30 August 2022). On this client itself, however, neither the voice processing nor the processing of the actual request is carried out. The client only recognizes the specified keyword and records the subsequent instructions. It sends the recording to its processing backend. There, voice processing first retrieves and interprets the request [65]. The request is then processed by means of machine learning approaches. Feedback loops are included so that if the user labels a response incorrect or unsatisfactory, the respecting request is used to train the models further and thereby refine them continuously. To put it simply, with every mistake the VDA makes, the system becomes smarter.