Requirements are fundamental to software development. They establish the foundation and scope of a software project. They determine the features that are to be developed. The entire project goal, for all stake-holders, is determined by the requirements gathered and how they are implemented. Stakeholders, like developers and testers, prepare their artifacts and develop components based on the requirements provided to them. It is important that the requirements are communicated to each stakeholder as they are intended. All stakeholders should understand the requirements as they are meant for the success of a project. The manner in which requirements are communicated is an essential element in ensuring the success of a software product. It is believed that written communication supplemented by verbal communication leads to a better quality of software. The aim of this study is to understand the magnitude of the im-pact of written and verbal communication of requirements on the quality of test cases and the efficiency of creating them for functional requirements. For this study, we have conducted a quasi-experiment wherein we provide experienced testers with abstract and concrete requirements and measure the impact of the mode of communication on the quality of test cases written. Our results suggest that verbal communication of requirements aids in creating good-quality test cases. But the quality comes at a cost of the efficiency of writing the test cases. The experiment shows that because of the additional verbal communication, the efficiency in creating test cases, measured in time, becomes lower, i.e. the quality of test cases increases, but creating them becomes less efficient.