Adaptive noise cancellation is a signal processing technique that is highly effective in suppressing additive interference or noise that corrupts a received target signal at the primary or main signal. The technique involves a self-adjusting adaptive filter that automatically transforms the reference signal into an optimal estimate of the interference corrupting the target signal before subtracting it from the received signal, thereby canceling or minimizing the effect of the interference at the noise canceller output. The adaptive filter adjusts itself continuously and automatically to minimize the residual interference affecting the target signal at its output. Adaptive noise cancellation is different from active noise control, which is a method in acoustics to reduce unwanted sound in physical spaces. Adaptive noise cancellation is used in various devices, including headphones, where it adjusts the strength of cancellation based on the level and type of surrounding noise. Adaptive noise cancellation earbuds are essentially active noise cancellation systems with adjustable thresholds. The technology is becoming increasingly popular and is a cost-effective solution compared to traditional noise-canceling headphones.