A TRF file is a data file created by Rational Acoustics Smaart, a program used by audio technicians and engineers to measure and analyze the acoustics of an environment. It contains a static "snapshot" of transfer function measurements, which consist of a measurement signal (the output from a device) and an input signal used for reference. TRF files were introduced with version 8 of Smaart and replaced REF files used by earlier versions of Smaart.

TRF file open in Rational Acoustics Smaart v8 Transfer function measurements allow users to analyze the output of input devices, such as microphones, guitars, and keyboards. The measurements are displayed as a graph in real-time. These graphs can be captured by selecting Capture or Capture All in the Data bar in the "Transfer" view. Captured transfer function measurements are saved in the TRF file. By default, TRF files are placed in the following directory: Documents\Smaart v8\Traces\Transfer Function\Session Data You can move them from this location. However, the transfer function measurements stored in the TRF files that are moved will no longer be displayed in Smaart. To import a TRF or older REF file, select File → Import → Trace Data File.... Rational Acoustics Smaart enables audio technicians to analyze sound systems and diagnose problems. It is used in a variety of venues, such as stadiums, concert halls, and churches. The name of the program is an acronym, which stands for System Measurement Acoustic Analysis Real-time Tool (SMAART).