The rise of ubiquitous computing has led to the rapid development of intelligent systems such as augmented reality (AR). AR is being employed for various usage including common tasks such as web browsing, navigating and controlling other internet of things (IoT) devices. In these types of system usage, similar to mobile phones, the presentation of notifications is inevitable. However, studies with regards to the effective delivery of notification signals within the AR environment is still lacking. Thus, the present study aims to investigate the effects of different output modalities (visual, auditory and multimodal) for presenting notifications during simple search and selection tasks within the AR system. Twenty individuals participated in a user study where they were asked to perform a simple search and selection task while using the AR device. Participants were asked to confirm the notifications that were presented at random in each trial. Results of the user study showed that multimodal notification signals (both visual and auditory) yielded a higher notification recognition rate and were rated as the most appropriate modality and most preferred among the conditions tested. Also, it was found that speech input modality was used more frequently in response to notifications, regardless of the output type. Several design implications were derived from the findings of the study.