In this paper, we propose a new smartphone-based hearing assistive system (SmartHear) using wireless technologies for individuals with mild-to-moderate hearing loss (HL). Our system is a stigma-free implementation of the personal frequency modulation (FM) system for people with HL, with enhanced accessibility, affordability, and customization and extension potentials. The SmartHear system consists of a smartphone running a mobile application and a Bluetooth handset coupled with the smartphone. The voice of the speaker is picked up by the smartphone placed near the speaker and transmitted wirelessly to the Bluetooth handset placed near the listener for listening. The transmission of the voice signals over radio waves overcomes the reverberation and ambient noise effects, and thus, the listener can listen from a distance with better clarity and ease. Speech intelligibility experiments demonstrate the efficacy of the proposed SmartHear system, showing an average improvement of 0.2 speech intelligibility score (on the scale of 0-1) across four typical audiograms for mild-to-moderate HL and in four signal-to-noise ratio conditions. A user survey reveals the favorable user experience with SmartHear in various dimensions, as compared to the conventional FM system.