A high-fidelity optical fiber microphone (HF-OFM) with hybrid frequency and fast response is theoretically and experimentally demonstrated by the nanofabrication techniques for real-time communication, which consists of a graphene oxide (GO) film, an Au nanocoating, and an air cavity. The internal stress of the film is increased by the method of mechanical tensile preparation, and the microphone response flatness is improved. Meanwhile, the structural design of the 3 nm Au nanocoating improves the acoustic pressure detection sensitivity by 2.5 times by increasing the reflectivity. The experimental result shows that single, dual, and triple frequency acoustic signal detection in the frequency range of 0.1 kHz–20 kHz are achieved with acoustic pressure sensitivities of 9.64, 9.66, and 8.9 V/Pa, as well as flat frequency response (<2 dB variation). The minimum detectable pressure (MDP) at 1 kHz is 63.25 μPa/Hz 1/2 . In addition, the high-fidelity real-time transmission of audio signals over an angle range of −90° to 90° is verified by a self-made acoustic pressure detection device. Such a compact, high sensitivity, and large measurement range HF-OFM is very promising for applications of oil leakage exploration, acoustic source location, and real-time communication.