Navigation Links
Carnegie Mellon scientists show brain uses optimal code for sound

Scientists at Carnegie Mellon University have discovered that our ears use the most efficient way to process the sounds we hear, from babbling brooks to wailing babies. These results represent a significant advance in our understanding of how sound is encoded for transmission to the brain, according to the authors, whose work is published with an accompanying "News and Views" editorial in the Feb. 23 issue of Nature.

The research provides a new mathematical framework for understanding sound processing and suggests that our hearing is highly optimized in terms of signal coding--the process by which sounds are translated into information by our brains--for the range of sounds we experience. The same work also has far-reaching, long-term technological implications, such as providing a predictive model to vastly improve signal processing for better quality compressed digital audio files and designing brain-like codes for cochlear implants, which restore hearing to the deaf.

To achieve their results, the researchers took a radically different approach to analyzing how the brain processes sound signals. Abstracting from the neural code at the auditory nerve, they represented sound as a discrete set of time points, or a "spike code," in which acoustic components are represented only in terms of their temporal relationship with each other. That's because the intensity and basic frequency of a given feature are essentially "kernalized," or compressed mathematically, into a single spike. This is similar to a player piano roll that can reproduce any song by recording what note to press when the spike code encodes any natural sound in terms of the precise timings of the elemental acoustic features. Remarkably, when the researchers derived the optimal set of features for natural sounds, they corresponded exactly to the patterns observed by neurophysiologists in the auditory nerves.

"We've found that timing of just a sparse number of spikes actually enco des the whole range of nature sounds, including components of speech such as vowels and consonants, and natural environment sounds like footsteps in a forest or a flowing stream," said Michael Lewicki, associate professor of computer science at Carnegie Mellon and a member of the Center for the Neural Basis of Cognition (CNBC). "We found that the optimal code for natural sounds is the same as that for speech. Oddly enough, cats share our own optimal auditory code for the English language."

"Our work is the only research to date that efficiently processes auditory code as kernalized spikes," said Evan Smith, a graduate student in psychology at the CNBC.

Until now, scientists and engineers have relied on Fourier transformations--initially discovered 200 years ago--to separate and re-constitute parameters like frequency and intensity as part of traditional sound signal processing.

"Our new signal processing framework appears far more efficient, effective and concise in conveying a rich variety of natural sounds than anything else," Lewicki said.

The approach by Smith and Lewicki dissects sound based only on the timing of compressed "spikes" associated with vowels (like cat vocalizations), consonants (like rocks hitting one another) and sibilants (ambient noise).

To gather sounds for their research, the scientists traipsed through the woods and recorded cracking branches, crunching leaves and wind rustling through leaves before returning to the laboratory to de-code the information contained in this rich set of sounds. They also discovered what they consider the most "natural" sound: if they play back a random set of spikes, it sounds like running water.

"We're very excited about this work because we can give a simple theoretical account of the auditory code which predicts how we could optimize signal processing to one day allow for much more efficient data storage on everything from DVDs to iPods," Lewicki said.

< p>"For instance, if we could use a cochlear implant to 'talk' to the auditory nerve in a more natural way via our discovered coding, then we could quite possibly design implants that would convey sounds to the brain that are much more intelligible," he said.


Source:Carnegie Mellon University

Related biology news :

1. Carnegie Mellon scientists develop tool that uses MRI to visualize gene expression in living animals
2. Robot-based system developed at Carnegie Mellon detects life in Chiles Atacama desert
3. Green catalyst destroys pesticides and munitions toxins, finds Carnegie Mellon University
4. Carnegie Mellon University research reveals how cells process large genes
5. Carnegie Mellon cyLab researchers work to develop new red tide monitoring
6. Team led by Carnegie Mellon University scientist finds first evidence of a living memory trace
7. Carnegie Mellon scientists create PNA molecule with potential to build nanodevices
8. Carnegie Mellon U. transforms DNA microarrays with standard Internet communications tool
9. Carnegie Mellon develops non-invasive technique to detect transplant rejection at cellular level
10. DNA conclusive yet still controversial, Carnegie Mellon professor says
11. Teens unaware of sexually transmitted diseases until they catch one, Carnegie Mellon study finds
Post Your Comments:

(Date:10/6/2015)... Track Group, Inc. (OTCQX: TRCK), a global ... a contract with the Virginia Department of Corrections to ... sentences under the Department,s oversight. Derek Cassell ... with the Virginia DOC will expand our footprint in ... position as a trusted leader in offender electronic monitoring ...
(Date:10/1/2015)... 1, 2015  Biometrics includes diverse set of ... characteristics, such as fingerprints, eye retinas, facial patterns, ... biometrics technology has been constantly increasing in ... years. In addition to the most prominent popular ... other means of biometric authentication are rapidly gaining ...
(Date:9/29/2015)... 2015 News facts: ... saving energy , Minimized design shrinks PC footprint ... Mode and embedded Fujitsu PalmSecure authentication enable enterprises to ... today shows that good things come in small packages, ... its enterprise desktop and mobile portfolio. Featuring workplace design ...
Breaking Biology News(10 mins):
(Date:10/12/2015)... THOUSAND OAKS, Calif. and BRUSSELS ... and UCB (Euronext Brussels: UCB) today presented additional findings from ... trial. 1 The findings were presented today in an ... Mineral Research (ASBMR) 2015 Annual Meeting in Seattle ... 2 --> The small exploratory sub-study ...
(Date:10/12/2015)... 12, 2015 This report covers the global ... type, products, applications, end-user markets and geographic segmentation. Forecasts ... The global cell expansion market generated revenue of roughly ... revenues of $9.7 billion in 2015 and $22.0 billion ... of 17.8% from 2015 to 2020. This report ...
(Date:10/12/2015)... octubre de 2015 El 8 de octubre, ... récord en el congreso con su declaración acerca del ... Plasma Awareness Week (IPAW), que se celebrará del 11 ... la Plasma Protein Therapeutics Association (PPTA) y ... , Aumentar la concienciación mundial acerca de la donación ...
(Date:10/12/2015)... 12, 2015 LabStyle Innovations Corp. ... Solution, today announced its Medical Director, Dr. Moshe ... MobiHealth,s 5th EAI International Conference on Wireless Mobile ... innovations in mobile and wireless technologies," the conference will ... from October 14 - 16, 2015. The conference is ...
Breaking Biology Technology: