A DIY audio experiment tested if listeners could distinguish sound through various conductors like copper, banana, and wet soil. Most couldn't, challenging beliefs about cable effects on audio quality.
© D. Novikov
An unusual blind experiment on the diyAudio forum has challenged conventional wisdom about "cable magic." Participants were asked to distinguish, by ear alone, an audio signal passed through various conductors—from professional copper cable to a banana and wet soil. The results were surprising: most listeners couldn't tell the difference.
The experiment was organized by a forum moderator named Pano. He prepared several versions of the same audio clip: the original from a CD and multiple re-recordings where the signal passed through different materials. The setup included about 1.8 meters of high-quality copper wire, a section of wet soil, an old microphone cable with soldered coins, a short "banana" wire, and a repeated control circuit.
All recordings were normalized to the same volume level and presented to participants for blind listening. Listeners didn't know which version they were hearing and had to identify which "conductor" the signal passed through. Out of 43 attempts, only 6 were correct—about 14%, a rate close to random guessing. Statistical analysis showed these results fall within the range of chance and don't confirm an ability to discern material effects on sound.
Pano noted that it's remarkable how similar these files sound, given that the "dirt" audio should be terrible but isn't, and all re-recordings should be obvious but aren't. He explains the effect by noting that such materials in an audio circuit act as additional resistance—they can attenuate the signal but don't introduce distortions detectable by human hearing.
The idea for the experiment came from watching the documentary Amigo, which described early 20th-century telegraph lines using the earth as a return conductor. This inspired the researcher to test how a similar principle would work for an audio signal.
The experiment's conclusion is simple yet inconvenient for enthusiasts of expensive accessories: in real-world conditions, human hearing often can't distinguish the influence of exotic or "unsuitable" conductors from ordinary cable—at least when it comes to subtle effects beyond obvious signal loss.