The cocktail party effect is the ability to listen selectively despite a noisy environment. The term comes from the observation that even in a crowded cocktail party room, a person can carry on a conversation with one person by “tuning in” to them and “tuning out” everything else.
If you think about it, it’s amazing that we can direct our focus to parse a desired noise source—say, a television—over the voice of the person sitting next to you. Of course, it also can be frustrating to the person being tuned out.
Psycho-acoustic studies have found that some sounds—a person’s name or a taboo word, for example—can disrupt selective listening. In a way it is like there are two channels: one for the “important” sound source you are laser-focused on and one for all other “unimportant” sound sources. Only certain stimuli can draw attention from the important channel to the unimportant.
In many instances, the ability to focus our listening is useful. Communication in a crowded room is just one example. However, in other instances this ability can be a problem. When driving, for example, it is important to focus on safely operating a vehicle, but with extra noise sources distracted driving can become a real danger.
Early work on the cocktail party effect was spurred by air traffic controllers who were having trouble communicating well with airplane pilots. Inquiry showed that part of the problem was that a single speaker was being used for communication with multiple pilots at a time. To remedy the problem, speakers were placed in different locations for different pilots. This, and additional research, has shown that selective listening is in part possible because of the ability to localize sounds.
Sound source localization is an ability due to binaural hearing, or hearing with two ears. For animals with two ears, the difference in time it takes sound to reach the ears gives the brain the information it needs to track where the sound originated. King penguins are able to find their young using this ability despite the noise of other penguins in their colony.
Some research has also found that the brain is able to focus its attention on the ear that is receiving the “important” sound better. This better-ear listening works together with visual cues, such as lip reading, and localization to increase understanding of the “important” signal.
As people age, their normal ability to filter out sounds decreases. This is further compounded in older adults with hearing loss. If someone is having a hard time understanding you in a noisy environment even though you can understand them easily, they may be struggling with a difficulty focusing their hearing. Try decreasing the number of competing sound sources or moving to a quieter environment to communicate better.
While the cocktail effect can help people communicate in crowded rooms, there are spaces that make it very difficult to communicate. If you think that a space is too loud, you can talk to an acoustical engineer or consultant to see what can be done to improve the acoustics of the space. Often, solutions are as simple as adding a rug or quieting the air conditioning system. If extra noise is interfering with your ability to communicate, consider talking with an acoustics professional.