The Sound of Dial-Up: Yann LeCun on the History of Adaptive Learning

KyleCranmer · x · 2026-08-09

Kyle Cranmer shares an interesting historical tech detail: the bizarre screech of a dial-up modem was actually the device characterizing the phone line in real-time.

The modem sent known signals and listened to what came back, learning which frequencies were distorted, how much noise was present, and how the signal was being smeared. From that little experiment, it could adapt its equalizer and choose how aggressively to transmit data.

He notes that Yann LeCun told him this history over lunch. The key idea originated from Robert 'Bob' Lucky at Bell Labs in the 1960s. Adaptive equalization allowed receivers to learn the characteristics of a communication channel and compensate for distortions, serving as an early, practical application of machine learning concepts in telecommunications.

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