Irrelevant speech effect

The irrelevant speech effect (ISE) or irrelevant sound effect is the degradation of serial recall of a list when sounds, especially speech sounds, are presented. This occurs even if the list items are presented visually. The sounds do not need to be a language the participant understands, or even a real language; human speech sounds are sufficient to produce this effect.

The theory covers speech as well as music or other background sounds. There have been many studies on this theory and it has been consistently proven that unrelated or irrelevant background sounds inhibits one's ability to perform well at serial recall.