Architectural Design Decisions (ADDs) capture the essence of relevant Architectural Knowledge (AK) and the underpinning rationale in order to produce well-designed software architectures. AK and design rationale might get lost if not captured at the same time when the architecture is discussed and modeled in early design phases. For years, this relevant knowledge has been captured using text templates and supported by a number of research tools. Nevertheless, as no commercial tool is still available combining AK capturing with UML notations to facilitate capturing the design decisions at the same time the architecture is modeled, is the major barrier to convince software architects and companies to invest in documenting the significant design decisions. As capturing AK using text templates requires an extra effort, we propose an approach to make the documentation process easier and reduce the effort thereof by using voice commands. In particular, we suggest an approach to: (i) capture ADDs using voice commands during design conversations, and (ii) link the captured ADDs to UML notations. Our approach integrates OctoUML, a modeling tool with voice commands for capturing design decisions by voice.