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3 HEARING ANALYZER FROM NEURAL SIMILAR ELEMENTS

Lecture



The auditory system of humans and animals represents
an effective device for analyzing complex
unsteady sound signals. It is used as
spectral and temporal methods of analysis, with
which the selection of informative features
produced by highlighting certain features of the time course
signal. From consideration of the auditory mechanisms of work
The system follows that a number of informational transformations
it is carried out, on the basis of laws or
principles that differ from those known in the art [46].
Therefore, the study of the principles of neural organization
auditory analyzer is determined by the desire to

3 HEARING ANALYZER FROM NEURAL SIMILAR ELEMENTS

to understand the general patterns of analyzers
brain, and the desire to use these patterns for
creating effective technical processing devices
temporary signals.
3.1. Basic Information Transformation
in the auditory system
In the neural structures of the auditory system are performed
the following operations: 1) determining the speed of the traveling
along the main membrane of the cochlea wave mechanical
fluctuations; 2) conversion of an analog quantity to
discrete by the principle of encoding its value by a number
excited elements; 3) increased sensitivity
systems in frequency and intensity due to mechanisms
lateral interaction of neurons; 4) increase
quantization frequency of the signal, allowing to estimate
time intervals shorter than
minimum interval of following nerve impulses in
fiber; 5) detecting the steepness of the leading edges
sound impulses; 6) change detection
sound frequency and intensity; 7) estimate of the amplitudes of the maxima
instant spectrum; 8) pitch detection;
9) detection of vowels and consonants; 10)
tonality detection; 11) determine the direction to
sound source; 12) estimation of the distance to the sound source;
13) determine the speed and direction of movement
sound source; 14) an assessment of the duration of short
compared with the durations of nerve impulses temporary
intervals; 15) object recognition and orientation in
space based on active location.
A number of auditory perception mechanisms in detail
investigated in [46]. Here we look at how it can be
neural-like structures capable of
implement basic neural operations
structures of the auditory analyzer. First we give
brief overview of the organization of the main departments
auditory analyzer.
3.1.1. 4natomo-morphological information
The main departments of the auditory system of higher
mammals are depicted in the diagram of Fig. 3.1. Sound vibrations
from the outer ear 1 through the eardrum 2 and

3 middle ear bones are exposed to the membrane
oval window 5, creating fluctuations in the liquid 6 and
the main membrane 7 of the auditory cochlea. Hearing snail
is a conical coiled
the tube, which in fig. 3.1 shown for clarity in
untwisted form. The main membrane is located inside
this tube along the length, expanding from the basal
end of the cochlea, where the oval window is located, to the apical.
The membrane is attached to the walls of the cochlea throughout
perimeter except for the apical end, in which
there is a gap - helicotrem 8. Length
the main membrane in humans is about 30 mm. All over
throughout the main membrane, cortis are attached to it
organ carrying hair cells 9 - receptors
organ of hearing. Receptors are arranged in rows along
membranes, while their number is less at the base of the cochlea,
i.e. the basal end (three rows for a person), and more
at the apex, or apical end (for a man five
rows).


The mechanical elasticity of the main membrane
varies along the length so that the region of maximum vibrations
moves in length when the sound frequency changes
signal. In this case, the region of excited
receptors so the distance from the helicotrem to the area
maximum excitation of hair cells
in proportion to the logarithm of the frequency of the audio signal.
Due to this, at the first stage, the following
audio signal conversion: signal frequency

encoded at the site of greatest membrane deformation
[49]. This kind of transformation was received in
literature on the physiology of hearing is the name of the "principle of place."
At the receptors, the input processes end -
dendrites of neurons making up the very first
auditory system neural formation - spiral
ganglion 11. Neurons of the spiral ganglion according to the type of connection with
receptors are divided into orthoneurons and spirononeurons. Or-
Toneyron is bound to
several hair cells. Spirononeuron has
extended “spiral” fiber that stretches along
membranes 2-3 mm and can come in contact with a large
the number of hair cells (per 1 mm of the membrane
about 80 receptors are located). Apparently
spirononeuron gathers information from a fairly large
membrane area in contrast to orthoneurons receiving
near


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Neurobionics

Terms: Neurobionics