|
Some recent research may shed new light on how the human brain extracts meaningful signals from noisy acoustic environments. In an article published in the open-access journal PLoS BIOLOGY, researchers describe how they investigated the role of the auditory cortex in informational masking by recording the brain responses of listeners performing an auditory detection task.
Informational masking is distinct from traditional "energetic" masking, which occurs when a target signal is rendered inaudible by a competing "masking" signal(s). In informational masking, both the target and masking signal are audible, but are not perceptually recognizable to listeners.
The researchers used this effect to isolate brain responses that correlated with conscious auditory perception among listeners who indicated when they heard a stream of repeating tones (target) embedded in a stochastic tone background (masker). You can listen to the sound files used in the auditory detection test (below):
Example of a Target Embedded in an Informational Masker (236 KB MP3)
The Isolated Target of the Example (236 KB MP3)
The Isolated Informational Masker of the Example (236 KB MP3)
From the results of their study, the researchers concluded that conscious sound perception originates from within the auditory regions of the brain, but not from the initial cortical region where sound is processed. According to the press release, this study will likely affect future research in this area:
Because many previous neuroimaging studies have used simple stimuli in unnatural contexts, such as pure tones in an otherwise quiet environment, this novel study will influence future research investigations aimed at uncovering the neural mechanisms of conscious perception in natural and complex environments.
You can read the complete article online at the following link:
"Neural Correlates of Auditory Perceptual Awareness under Informational Masking"
Comments, questions or suggestions? Email me at rich.pell@verizon.net.
Related links:
Audio Coding: An Introduction to Data Compression - Part 1 | Part 2 | Part 3
How audio codecs work - Psycoacoustics
Audio coding artifacts: What to listen for
|
