Potential opportunities for unmanned aircraft systems (UAS) to offer societal benefits are accompanied by noise impact risks. Accordingly, it is important to develop greater understanding of perception and response to UAS sound. A laboratory listening experiment was undertaken to address this aim by investigating psychoacoustics of UAS sound exposure. The experiment incorporated contextual auditory and soundscape factors by embedding spatially-rendered UAS sounds within urban acoustic environments. The UAS covered varying aircraft designs, operating modes and numbers of flights. The experiment was focussed on determining noticeability and noise annoyance. The results indicate that annoyance responses were influenced by UAS type, operational mode, sound characteristics, quantities of flights, and the ambient acoustic environments in which UAS events occurred. Annoyance also appeared to have associations with personal attitude towards advanced air mobility technology, and with classification of residence area. Noticeability appeared to be influenced by UAS type, operating mode, loudness and ambient environment.