How can you hear what someone is saying at a crowded party – even when they are halfway across the room? It’s all about the cocktail parties effect.
The cocktail party effect refers to the ability of people to focus on a single talker or conversation in a noisy environment. For example, if you are talking to a friend at a noisy party, you are able to listen and understand what they are talking about – and ignore what other people nearby are saying. It’s basically a form of aural eavesdropping.
By wearing two hearing aids, particularly two digital hearing aids that can communicate together instantaneously, people with hearing loss can fight the cocktail party effect. The interaction between the pair simply helps users better determine the location of a sound.
The cocktail party effect was first described by Colin Cherry, a British scientist, in the early 1950s. Cherry conducted a series of experiments to determine how people listen.
In the first, he played back two different messages (voiced by the same person) through both ears of a set of headphones. He then asked the participants to write down one of the messages. After some effort and concentration they could, eventually, separate one of the messages from another.
The real surprise, though, came in the second series of experiments. Here, the participants were played one message to the left ear and one message to the right ear (again voiced by the same person). Suddenly, they could separate the messages from each other – and even shift their attention between the two.
Cocktail Effect Psychology
Imagine yourself at a party with tens of people around trying to talk to each other. There are a number of overlapped voices talking, the music playing, drink glasses clinking and what not. Among that cacophony of sounds is a friend speaking in front of you, not much louder than the background noise itself. You can still make out what he is saying.
There’s something about the human speech, the auditory system and the high-level language processing system that enables you to conjure up a highly selective attention towards your friend, letting you to listen to him talk, as if muting everything in the background. It happens so naturally and in such a subtle manner that you might not even appreciate the presence of any out-of-the-world processing your brain is doing to make you understand your friend’s speech at such events.
This effect, known as the cocktail party effect has been known for long and the exact mechanics of how the human brain manages to deal with it has baffled scientists for several years. However years of contemplation and the rise in computing power has enabled some amazing breakthroughs in this area. Like say, take this experiment for example.
How does cocktail party effect work for computers?
Let’s say a cocktail party where you and another person are taking at the same time, has two microphones kept at a certain distance from each other. Both microphones will record both your voices. To just listen to one voice, at least to make a computer do that may sound like an extremely tough job to do. But here’s the thing. One microphone, which is closer to you records your voice slightly louder and slightly fainter in the other microphone. If both these recordings are made to go through a single very intelligent line of code, the code can almost very clearly output two files with your clean voice in one file and the other person’s in the second file. This single line of code is the Cocktail party algorithm, its generic name being – Independent Component Analysis (ICA). ICA is a special case of something called the Blind Source Separation (BSS) or Blind Signal Separation. It involves a high level of linear algebra and uses something called the Singular value decomposition.
