What does the "leaky filter" mean in Treisman's attenuation model?

In Treisman's attenuation model, the "leaky filter" concept refers to the idea that while attention acts as a filter for incoming information, it does not completely block irrelevant information. Instead, some unattended messages can still be processed to a certain degree. This means that while we focus on specific information—like a conversation at a noisy party—our cognitive system can still pick up on important or salient aspects of the background noise, like someone's name or a sudden loud sound. Thus, this model posits that filtering occurs but does not entirely eliminate the processing of unattended stimuli, allowing for a selective but not exclusive attentional system. This is particularly relevant in everyday scenarios where partial awareness of surroundings is more realistic than a complete filter.