For approximately 50 years, individuals worldwide have reported an unexplained low-frequency hum, often heard indoors but difficult to detect outdoors. Glen MacPherson, who first heard it on Canada's west coast, established an interactive database to gather similar experiences. A new study published in PLOS One tested 28 people in Germany and suggests that, for many, the source of the sound may not be external but rather a form of low-frequency tinnitus. The Hum first gained attention in Bristol, England, during the 1970s, with various theories about its origins, including industrial noise and natural sources. However, the sound's selectivity, affecting some individuals while others remain oblivious, complicates its explanation. The study found that while two participants had heightened sensitivity to low frequencies, most did not, leading researchers to propose that for many, the sound may originate within the auditory system itself. This research highlights a gap in understanding how the auditory system processes low-frequency sounds, offering validation to those who have long felt dismissed in their experiences.