Early reflections are considered to be important for the impression of concert hall acoustics. So far, the audibility of room reflections have mostly been studied in strongly simplified and artificial settings. In this study, spatial room impulse response measurements of a chamber music hall are used. Wall reflections are identified using spatial analysis. Subsequently, their levels and directions are modified and the resulting response is rendered to a multi-channel loudspeaker array. A listening test explores the audibility threshold of these modifications and their influence on perceptual attributes such as width, clarity and loudness. The results have applications in the optimization of concert hall designs and efficient virtual acoustic rendering.