Member station engineers have suggested that they could use an audio reference tone for lining up gain on their computer audio systems. We regularly use one to check calibration on audio cards and editors at NPR Labs, which is a simple 1kHz sine wave recorded at precisely -20dBFS. It is sampled at 48kHz in 16-bit PCM WAV format.
Download or play back the Reference Tone
An audio level meter will play this at -20 dBFS, and approximately -20 LUFS on the ITU-R.BS-1770 loudness meter (as shown at left), so it is useful for aligning loudness meters to the digital audio system.