Whether you’re at a crowded bar or at a party with your significant other, chances are you will both interact with an array of partygoers throughout the course of the night. Couples have the ability to easily hear and ignore their longtime partner’s voice due to the cocktail party effect, according to a recent study.

Individuals may find themselves immersed talking to a single person in a crowded room trying to decipher the words of the one person in which they are talking to despite all the background noise. This phenomenon, known as the cocktail party effect, has both psychological and neurological components to explain why partygoers frequently engage in this behavior.

Scientists believe all the sounds enter the ear as one harsh roar, but as the brain processes this information, it tunes into one sound, such as a person’s voice, and begins to filter out the rest, says Penn Medicine. While areas of the brain involved in hearing continue to respond to different voices, areas devoted to language appear to only respond to the selected speaker. The psychological component of the cocktail party effect suggests that it is the sound the individual wants or needs to hear, which is why they are able to tune into it despite the noise volume in a crowded area. Overall, this effect sharpens the partygoer’s ability to filter out a range of other stimuli and solely focus on a single conversation in a noisy room, which can lead couples to easily hear or ignore each other in similar social settings.

Published in the journal Psychological Science, a team of researchers from Queen’s University in Ontario, Canada, sought to examine if couples were effectively able to distinguish and tune into their spouse’s voice in a series of recordings of strangers’ voices. Twenty-three couples, ranging in age from 44 to 79 years old, all of whom had been married for at least 18 years, were recruited for the study. The researchers used a coordinate-response measure procedure to show that people can exploit knowledge of a highly familiar voice, such as their spouse’s, not only to track it better in the presence of an interfering stranger’s voice but to also ignore it to comprehend a stranger’s voice more effectively.

The participants were first asked to record themselves reading a set of 128 sentences. Later, the couples put on headphones and listened to three voices that were played at once: their partner’s, plus the voices of two strangers. The participants had to report what their partner was saying, and then they were asked to report what one of the unfamiliar voices was saying.

Overall, the couples were found to be equally good at hearing their partner against a competing stranger’s voice no matter what age. The middle-aged couples were found to be better at focusing on the stranger’s voice when their partner was talking at the same time compared to the other age groups. However, while the participants focused on their partner’s voice when they were speaking the key information, they were also found to be easily ignored when the strangers’ voices held the necessary information they needed to hear.

“You’re at a party and you’re trying to listen to a stranger who’s talking to you, a very interesting stranger — and at the same time your partner is yammering away,” said Ingrid Johnsrude, lead researcher of the study, the Daily Mail reports. “This suggests you can ignore what your partner is saying so as to focus in on what that very interesting stranger is saying.”

Although the researchers did not delve into the reasons as to why this happens, they speculate the deep familiarity of a spouse’s voice helps couples organize sound sources. Therefore, the more familiar the sound, the easier the spouse will be able to pick it up when they want to or let it fade into the background.

While it is known that hearing tends to decline with age, the study revealed the older participants remained very perceptive when it came to their husband or wife. This finding lends to the possibility that older listeners can use their familiarity with a speaker’s voice to lessen the effects of sensory and cognitive decline with old age. William Yost, a professor in speech and hearing science at Arizona State University, who was not involved in the study, told NBC News he believes this study helps address "in the future, the design of hearing aids may have to include understanding how the aid can assist cognitive as well as auditory processing.” A better understanding of the cocktail party effect can help people who have trouble differentiating a single voice in a crowded room.

Johnsrude is currently working on another study that features couples who have spent fewer than five years together and their ability to easily hear and/or ignore their partner’s voice. Similar to her findings in the previous study, younger couples find it much harder to ignore their partner’s voice, even if they wanted to.

“Not only could these younger people not ignore their spouse, they would make mistakes,” said Johnsrude to NBC News. “When they were trying to attend to a novel talker, they would report the [stranger's] voice as their partner’s. Which was, we thought, a rather romantic turn of events.”

The cocktail party effect can help harness longtime couples’ relationships but also put them in jeopardy when their voices can be easily ignored for a long time.

Source: Alexander E, Carlyon RP, Hakyemez H et al. Swinging at a Cocktail Party Voice Familiarity Aids Speech Perception in the Presence of a Competing Voice. Psychological Science. 2013.