This paper investigates a new technology for Hybrid flexible delivery (known as HyFlex), as implemented at King's College London. The relatively novel character of HyFlex, of mixing synchronously on-line and in-room teaching, and the recent changes due to the COVID-19 pandemic mean this use of the technology and teaching model is largely new to the UK. This research evaluated audio quality in the context of a HyFlex technical environment. The paper provides a high-level overview of the process of designing a HyFlex solution and presents a detailed evaluation of the impact of reverberation in relation to the accuracy of automatically generated subtitles and the influence of microphone selection. The paper shows that there was a significant relationship between the reverberation, the audio quality, and the subtitling system, which is important as past studies highlighted audio quality is key for the students' experience. It presents a viable and simple methodology to estimate the audio quality on installed HyFlex systems to improve the students experience in a hybrid teaching environment.