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The fundamental function of this part of the ear is to gather sound energy and deliver it to the eardrum. Resonances of the external ear selectively boost sound pressure with frequency in the range 2–5 kHz. [2] The pinna as a result of its asymmetrical structure is able to provide further cues about the elevation from which the sound originated.
It considers the brain a dynamical system and uses differential equations to describe how neural activity evolves over time. In particular, it aims to relate dynamic patterns of brain activity to cognitive functions such as perception and memory. In very abstract form, neural oscillations can be analyzed analytically.
Neuronal activity at the microscopic level has a stochastic character, with atomic collisions and agitation, that may be termed "noise." [4] While it isn't clear on what theoretical basis neuronal responses involved in perceptual processes can be segregated into a "neuronal noise" versus a "signal" component, and how such a proposed dichotomy could be corroborated empirically, a number of ...
As noise levels increase, one would assume a lowered ratio and therefore diminished signals. A diminished signal can be detrimental to a cell if neuronal maintenance is disrupted, or more importantly a necessary inhibitory response is lost. [10] Noise limits the fidelity of a neuron's response to a signal or stimulus.
Acoustic resonance is also important for hearing. For example, resonance of a stiff structural element, called the basilar membrane within the cochlea of the inner ear allows hair cells on the membrane to detect sound. (For mammals the membrane has tapering resonances across its length so that high frequencies are concentrated on one end and ...
An fMRI device works by detecting changes in neural blood flow that is associated with brain activity. fMRI devices use a strong, static magnetic field to align nuclei of atoms within the brain. An additional magnetic field, often called the gradient field, is then applied to elevate the nuclei to a higher energy state. [5]
The brain utilizes subtle differences in loudness, tone and timing between the two ears to allow us to localize sound sources. [10] Localization can be described in terms of three-dimensional position: the azimuth or horizontal angle, the zenith or vertical angle, and the distance (for static sounds) or velocity (for moving sounds). [ 11 ]
In mammalian outer hair cells, the varying receptor potential is converted to active vibrations of the cell body. This mechanical response to electrical signals is termed somatic electromotility; [13] it drives variations in the cell's length, synchronized to the incoming sound signal, and provides mechanical amplification by feedback to the traveling wave.