Monday, January 23, 2012

Why It's Hard to Listen to Two People Talking at One Time

Researchers from Carnegie Mellon show us why it's hard for us to listen to two people talking at one time. In addition to listening to the individual messages, we have to use bilateral brain pathways to resolve conflicts in what we heard (or what we think we heard) and piece together information.

Developmentally, the need for bilateral brain coordination and interhemispheric pathways is plenty good reason for why some students (and nearly all young children) may have a harder time listening over background noise or focusing on a teacher's comments while a classmate is talking.

In the figure at left (see this study), see how the digit (number) recall of 6-9 year old children goes steadily down as background noise goes up.

There is an entire science of noisy classrooms - but briefly, background noise in occupied classrooms is significant  (48-68 dB in one study) and it significantly affects classroom performance particularly for subjects like reading, spelling, attention, and behavior. And yes - it also affects teacher performance. Children with hearing loss or auditory processing disorders are affected more than their non-impaired peers.


  1. I would also add that children with attention issues are not only more sensitive to background noise, but that many of things that other kids would never notice (like the air conditioning turning on) are more noticeable to them.

    I also wonder if they are more affected by background noise, of if for them, background noise doesn't really exist; i.e. all noise competes on the same channel. This would seem to fit in with the difficulty they have in assigning importance to auditory or visual content.

    Do you agree?

  2. Could you provide the citation or a link to the Carnegie Mellon study on brain pathways activated while listening to two voices at once? I would be most grateful!

  3. hol, both things can happen. For some -the difficulty is with the central adjustment balancing inputs (turning down some sounds, focusing others) - while others may have a fixed frequency loss for which the brain tries to increase reception of surrounding frequencies.

    Hi Carol, Sorry - did we forget the link? Here it is:

    Brain activation for language dual tasking...

  4. Thank you for your article. I would like to mention that I previously worked in an office, typically around four or five people in the vicinity. Three of them showed a remarkable propensity for listening to two or three people at once. Two of them were fluent in at least two languages. One was from Scandinavia and the other was Hispanic. I would like to propose that individuals fluent in two or more languages somehow have a greater propensity for understanding two or more people talking at the same time. As to the Hispanic worker, he was absolutely remarkable. It seemed he could somehow talk to three people simultaneously, zig-zaging his conversations back and forth as each person would say something. And his overall understanding of our products, our pricing, and our deliveries was remarkable as well.

    I would like to add that I can hear many types of sounds a lot better than other people can. The first thing I "tune into" (become aware of) when entering an indoor or outdoor place, is almost invariably the music. I can only recall one other person telling me that the same thing happens for her. I reckon either my auditory system is acute, or some other system is acute.

    Thanks for allowing me to post.

  5. I have two, seemingly contradictory, thoughts on this matter. First, on a personal note, it could not be more true. If the TV is on, or even if I'm reading something, much to the chagrin of my wife and children, I cannot "hear," let alone focus, on what anyone is saying to me. Thus, another good reason to turn off the TV and put down the newspaper when interacting with others -- especially at the dinner table.

    Now, having said that, I am familiar with Learning Styles Inventory, which states there are two types of learners -- analytic and global. Analytics (of which I am a prime example), can only focus on one thing at time and need silence if we are to learn. Globals, on the other hand, are multitaskers, and PREFER background noise when learning. These are people who need the TV or radio going in the background, or need some noise in the classroom in order to concentrate. Indeed, my kids can play video games, or play their musical instruments, and maintain a conversation at the same time . . .

    Now, I'm sure the globals are not "listening" to the background noise, but they seem to need it to be there. So, just a thought about the classroom noise -- it may actually be beneficial to some students.

    Rob Stevens

  6. Sometimes the need for background noise is present for those who are bothered by auditory distractions. In research labs, they do a "auditory oddball" stimulus. Music can have a mild alerting effect - and if it's overlearned it won't be distracting (because the musical imagery of the music is known so well by the listener).

    It's an interesting though, Rob putting together Learning Styles inventories and preferences such as these for silence or background noise. The diffuse attention literature (latent inhibition) may also be relevant. Maybe people who require silence have higher tendencies toward diffuse attention (they may notice more as different - or increased sensitivity to oddball stimuli). Higher diffuse attention is associated with higher levels of lifetime creative achievement.

  7. What's up? I am worried because it has been 4 weeks since your last post. Please don't stop blogging. I count on you for brain news.

  8. Hi Aly V and sorry for the missed weeks.

    We've been busy planning a conference for dyslexia and doing a lot of travel - we do have articles that we're planning to post - and hope to be back in the routine next week.

  9. Wondering if this may be connected 7 y.o.daughter, who has some auditory and visual processing issues (regulation/overresponsivity; not on the spectrum) mentioned for the first time the other night that, for her, individual words have both images and sounds associated with them. "Shiny" is a golden chalice with a metallic scraping sound, for example. Seems to happen with both written and spoken words; I gave her a few random "test" words and her responses were quick and definitive for each.

    With this internal noise going on, it seems no wonder that she'd find it difficult to regulate additional input. Might this be tied in some way to bilateral processing as well?

  10. Wow. This may have saved me and my family a lot of headaches. For me EVERYTHING is the same level of sound. Being that inventions pop in my head I think I can get closer to solving the Problum. Considering I have survived six concussions at the same time. Front middle and back, Both hemispheres.