All sensations can be characterized in terms of their properties. The main properties include: quality, intensity, duration, spatial localization, absolute And relative threshold.

Quality - this is a property that characterizes the basic information reflected by this sensation, distinguishing it from other types of sensations and varying within this type of sensation. For example, taste sensations provide information about certain chemical characteristics subject: sweet or sour, bitter or salty; the sense of smell also provides us with information about the chemical characteristics of the object, but of a different kind: a floral smell, the smell of almonds, the smell of hydrogen sulfide, etc .; auditory sensations give information about the pitch, timbre and volume of the sound, etc.

Feeling intensity is his quantitative characteristic and depends on the strength of the acting stimulus and the functional state of the receptor, which determines the degree of readiness of the receptor to perform its functions. For example, if you have a runny nose, the intensity of perceived odors may be distorted.

Duration of sensation is its temporal characteristic of sensation. It is also determined by the functional state of the sense organ, but mainly by the time of action of the stimulus and its intensity.

It should be noted that sensations have a so-called latent (hidden) period, i. when a stimulus is applied to the sense organ, the sensation does not occur immediately, but after some time. latent period various kinds sensations is not the same, so for tactile sensations from is 130 ms, for pain - 370 ms, and for taste - only 50 ms.

Spatial localization irritant. The analysis carried out by the receptors gives us information about the localization of the stimulus in space, i.e. we can tell where the light is coming from, where the heat is coming from, or what part of the body is affected by the stimulus.

These described properties of sensations to one degree or another reflect quality characteristics sensations. However, no less important are quantitative parameters basic characteristics of sensations, in other words, degree of sensitivity .

There are two types of sensitivity: absolute sensitivity And sensitivity to difference.

Under absolute sensitivity imply the ability to sense weak stimuli, and by sensitivity to difference - the ability to perceive differences between stimuli.

Sensitivity thresholds Those are her limits. Our sensitivity range is limited by the lower and upper absolute thresholds.

The minimum value of the stimulus at which a sensation first occurs is called absolute lower threshold of sensation.

Stimuli, the strength of which lies below the absolute threshold of sensation, do not give sensations, but this does not mean that they do not have any effect on the body. So sound stimuli lying below the absolute threshold of sensation can cause a change in the electrical activity of the brain and dilation of the pupil.

Along with the lower one, there is also upper absolute threshold, i.e. the maximum intensity of the stimulus at which sensation is still possible. Above the upper threshold, pain occurs or the sensation disappears.

The absolute lower threshold of sensation characterizes absolute sensitivity level of this analyzer.

Different analyzers have different sensitivities.

There is an inverse relationship between absolute sensitivity and the threshold value: the lower the threshold value, the higher the sensitivity of this analyzer.

Another characteristic of sensitivity is sensitivity to discrimination. It is also called relative or differential, because. is sensitivity to a change in stimulus.

The smallest difference between two stimuli that causes a barely perceptible difference in sensations is called threshold of discrimination or difference threshold.

The threshold for distinguishing sensations is determined by the ratio

DI / I \u003d const (Bouguer-Weber law),

where DI is the amount by which the original stimulus that has already generated the sensation must be changed in order for the person to notice that he has really changed; I - the value of the current stimulus.

Moreover, the value characterizing the discrimination threshold is constant for a particular analyzer. For the visual analyzer, this ratio is approximately 1/1000, for the auditory - 1/10, for the tactile - 1/30.

The properties of sensations are thresholds.
The absolute threshold of sensation- this is the minimum intensity at which the signal begins to be perceived by the subject. For different types sensations have their own thresholds, sometimes significantly different from each other.
Relative (differential) threshold, expressed by the Weber-Fechner law, shows what minimum increment of intensity is necessary in order to sense a change in the signal. Naturally, the higher the initial level, the higher the threshold. With a quiet sound, it is enough to turn up the volume slightly so that everyone can feel the difference. If loud music is heard or a strong noise is heard outside the window, then their slight amplification is not caught by us.

Leading properties of sensations It is also adaptation, sensitization and synesthesia.

Adaptation- this is the ability of the sense organs to adapt, get used to a new, or changed intensity, signal. There are, for example, dark and light adaptation, adaptation to temperature or surface quality. Some of them we experience quite often in Everyday life. So, going from a sunny street into a dark room, at the first moment we see almost nothing. However, rather quickly, the eyes get used (adapt) to the twilight, and we begin to distinguish the surroundings, at first vaguely, and then more and more clearly. Likewise, going to bright light from the darkness, at the first moment we poorly distinguish the surroundings, and then light adaptation helps us to see objects. When we dip our hand into hot water, we first feel a high temperature, but gradually the hand gets used to it and ceases to feel the water as hot (or excessively. There are only two types of sensitivity that a living being cannot get used to - pain and hearing. This is due to biological expediency, so how, getting used to, for example, pain, a living creature reduces the danger threshold and it can die. In a person, speech (i.e., sound) also contains extremely important information for life.You can try to get used to the sound, not notice it (like pain), but it is worth weakening attention - and the sound or pain is again realized, while we will not be able to recreate the sensations of hot water or blindness in a dark room under any circumstances.

Sensitization associated with an increase in sensitivity, a decrease in its threshold. This property arises in connection with increased motivation or certain conditions of life, the requirements of professional activity. Thus, when we are highly interested, we may hear sounds that we would not hear in a normal situation (for example, you want to hear a quiet speech, knowing that the conversation is about you). Musicians distinguish overtones in a sound that seems to non-professionals to be a single tone. In the same way, artists see different shades in the same color for others. Living conditions also contribute to an increase in sensitivity, for example, northern peoples distinguish several shades of white (the same for the rest), since a lot in their life depends on the state of snow.

Synesthesia is based on the joint work of several analyzers. So, we can associate color with sound (for example, color music) or with temperature sensations (warm or cold tones), etc. Synesthesia also helps to compensate for the shortcomings of the activity of some kind of analyzer, for example, people who are hard of hearing distinguish sounds by vibration. In any case, such a joint feeling is more stable and better stored in memory than usual.

All of them can be divided into three types: interoceptive, proprioceptive and exteroceptive. The first group includes sensations arising from impulses reaching us from the internal environment. human body; to the second - reflection of information about the location of the body in space, providing regulation and correction of movement; to the third group - sensations that appear due to signals from outside world that create the basis for conscious actions and human behavior. Different types characterize certain properties of sensations, but we will talk about this a little lower.

The group of interoceptive sensations brings to the brain information about the internal processes occurring in the human body. This species is the most ancient and is considered to be less conscious than others.

Proprioceptive sensations are reflected information about the location of the human body in space. They are playing leading role in the regulation of movement. Peripheral receptors are found in joints, muscles, tendons, and ligaments. The excitations that occur in these receptors refer to the sensations that occur when the muscles tense and relax and changes in the position of the joints. This group includes a special kind of sensitivity, which is called "a sense of balance." Their receptors are located in and associated with the vestibular apparatus.

The third, most common group is represented by exteroceptive sensations, which convey to the human body various information coming from the outside world. There are distant and contact sensations. Contact can be caused by influences directly applied to the surface of the body or the perceiving organ. Examples of contact sensations are touch, taste. Distant ones are caused by an irritant acting on the receptors of analyzers at a distance. These include sense of smell, hearing and vision.

Types of sensations

The most famous since the time of Aristotle are such types as auditory, visual, olfactory, tactile and gustatory. But a person also has specific ones that give information about acceleration, vibration, time. A person does not feel some types of energy at all at the level of consciousness (for example, radiation, ultraviolet and ultrasound, infrasound, and others). Different species can interact with each other.

Properties of sensations

Types of sensations have differences in the sources that generate them, and other differences. They have not only specific features, but also general properties of sensations: quality, intensity, duration.

Intensity is a characteristic determined by the strength of the stimulus and the state of the receptor.

Quality is a feature that distinguishes it from other forms of sensation and varies within this type of sensation.

Duration is a temporal characteristic and determines the duration of the stimulus and its intensity.

When the stimulus acts on the receptors, the sensation may not occur immediately, but after some time. This period is called latent, which is different for different types of sensations.

These are the properties of sensations that we have considered in this article.

So, we found out that sensation is a mental cognitive process, which consists in reflecting the properties of objects and the internal states of the body when exposed to stimuli on the receptors of the sense organs. The functions of sensations are to quickly and timely convey to the central nervous system human information about the state of the internal and external environment.

All sensations can be characterized in terms of their properties. Moreover, properties can be not only specific, but also common to all types of sensation. The main properties of sensations include: quality, intensity, duration and spatial localization, absolute and relative thresholds of sensations.

Quality - this is a property that characterizes the basic information displayed by a given sensation, distinguishing it from other types of sensations and varying within this type of sensation. For example, taste sensations provide information about some of the chemical characteristics of an object:

sweet or sour, bitter or salty. The sense of smell also provides us with information about the chemical characteristics of the object, but of a different kind: the smell of flowers, the smell of almonds, the smell of hydrogen sulfide, etc.

It should be borne in mind that very often, when talking about the quality of sensations, they mean the modality of sensations, since it is the modality that reflects the main quality of the corresponding sensation.

Intensity sensation is its quantitative characteristic and depends on the strength of the acting stimulus and the functional state of the receptor, which determines the degree of readiness of the receptor to perform its functions. For example, if you have a runny nose, the intensity of perceived odors may be distorted.

Duration Feelings are a temporal characteristic of the sensation that has arisen. It is also determined by the functional state of the sense organ, but mainly by the time of action of the stimulus and its intensity. It should be noted that sensations have a so-called patent (hidden) period. When a stimulus is applied to the sense organ, the sensation does not occur immediately, but after some time. The latent period of different types of sensations is not the same. For example, for tactile sensations, it is 130 ms, for pain - 370 ms, and for taste - only 50 ms.

The sensation does not arise simultaneously with the beginning of the action of the stimulus and does not disappear simultaneously with the termination of its action. This inertia of sensations is manifested in the so-called aftereffect. A visual sensation, for example, has some inertia and does not disappear immediately after the cessation of the action of the stimulus that caused it. The trace from the stimulus remains in the form of a consistent image. Distinguish between positive and negative series

Fechner Gustav Theodor(1801 -1887) - German physicist, philosopher and psychologist, founder of psychophysics. Fechner is the author of the programmatic work "Elements of Psychophysics" (1860). In this work, he put forward the idea of ​​creating a special science - psychophysics. In his opinion, the subject of this science should be the regular correlations of two types of phenomena - mental and physical - functionally interconnected. The idea put forward by him had a significant impact on the development of experimental psychology, and the research that he conducted in the field of sensations allowed him to substantiate several laws, including the basic psychophysical law. Fechner developed a number of methods for indirect measurement of sensations, in particular three classical methods for measuring thresholds. However, after studying the successive images caused by the observation of the sun, he partially lost his sight, which forced leave him psychophysics and philosophy. Fechner was a comprehensively developed person. Yes, he has published several satirical works under the pseudonym "Doctor Mises".

images. positive serial image corresponds to the initial irritation, consists in maintaining a trace of irritation of the same quality as the current stimulus.

Negative serial image consists in the appearance of a quality of sensation that is opposite to the quality of the irritant. For example, light-darkness, heaviness-lightness, heat-cold, etc. The appearance of negative sequential images is explained by a decrease in the sensitivity of this receptor to a certain effect.

And finally, sensations are characterized spatial localization irritant. The analysis carried out by the receptors gives us information about the localization of the stimulus in space, that is, we can tell where the light comes from, the heat comes from, or which part of the body is affected by the stimulus.

All of the above properties to some extent reflect the qualitative characteristics of sensations. However, the quantitative parameters of the main characteristics of sensations are no less important, in other words, the degree sensitivity. The human sense organs are surprisingly fine working apparatuses. Thus, Academician S. I. Vavilov experimentally established that the human eye can distinguish a light signal of 0.001 candles at a distance of a kilometer. The energy of this stimulus is so small that it would take 60,000 years to heat 1 cm3 of water by 1°C with its help. Perhaps no physical device has such sensitivity.

There are two types of sensitivity: absolute sensitivity And sensitivity to difference. By absolute sensitivity is meant the ability to sense weak stimuli, and by difference sensitivity is the ability to sense subtle differences between stimuli. However Not any irritation causes sensation. We do not hear the ticking of the clock in the other room. We do not see stars of the sixth magnitude. In order for a sensation to arise, the strength of the stimulus must have a certain amount.

12.Adaptation and sensitization of sensations

adaptation called a decrease or increase in the sensitivity of the analyzers as a result of continuous or prolonged exposure to stimuli. Due to adaptation, sensations that were sharp and strong at the initial stimulation of the receptor, then, with the continuous action of the same stimulation, weaken and may even disappear altogether. An example is adaptation to long-acting odors. In other cases, adaptation is expressed, on the contrary, in an increase in sensitivity. For example, during the transition from light to darkness, we do not distinguish objects around us. However, after some time, this feeling becomes possible.

Sensitization is called an increase in the sensitivity of analyzers in connection with an increase in the excitability of the cerebral cortex under the influence of certain stimuli. For example, the intake of caffeine or any other stimulants enhances the nervous activity of the cortex, in connection with which the sensitivity of the analyzers also increases: auditory, visual, tactile and other sensations begin to flow more clearly than under normal conditions.

The sensitivity of some analyzers may increase under the influence of the simultaneous activity of other analyzers. For example, when the eye is irritated with light of optimal intensity, at which the visual function is carried out easily and quickly, sensitivity to sounds also increases at the same time; visual acuity and color sensitivity increase with simultaneous prolonged exposure to moderate sounds, sensations of cold increase auditory and visual sensitivity; on the contrary, hot temperatures and a stuffy atmosphere lead to their decrease (S. V. Kravkov). Rhythmic auditory sensations contribute to an increase in musculoskeletal sensitivity: we feel and perform our movements better if physical exercises are accompanied by music.

physiological basis sensitization of sensations are the processes of interconnection of analyzers. The cortical parts of some analyzers are not isolated from others, they take part in general activities brain. For this reason, the movement nervous processes in the central departments of some analyzers, according to the laws of irradiation and mutual induction, is reflected in the activities of other analyzers.

This relationship is strengthened when the functions of different analyzers are involved in some common activity. For example, musculo-motor and auditory analyzers can be organically connected with the performance of movements (the nature of the sound corresponds to the nature of the movements), and then one of them enhances the sensitivity of the other.

The sensitivity of the analyzers sometimes also increases due to the fact that they have not been affected by the corresponding stimuli for a long time. For example, the sensitivity of the eye to light after a 30-40 minute stay in the dark can increase 20,000 times.

13. Interaction of sensations and synesthesia

The individual sense organs that we have just described do not always work in isolation. They can interact with each other, and this interaction can take two forms.

On the one hand, individual sensations can influence each other moreover, the work of one sense organ can stimulate or inhibit the work of another sense organ. On the other hand, there are deeper forms of interaction in which the sense organs work together causing a new, maternal kind of sensitivity, which in psychology is called synesthesia.

Let us dwell separately on each of these forms of interaction. Research conducted by psychologists (in particular, the Soviet psychologist S. V. Kravkov), showed that the work of one sense organ does not remain without influence on the course of the work of other sense organs.

So, it turned out that sound stimulation (for example, whistling) can sharpen the work of visual sensation, increasing its sensitivity to light stimuli. In the same way, some odors also affect, increasing or decreasing light and auditory sensitivity. A similar influence of some sensations on other sensations, apparently, occurs at the level of the upper parts of the trunk and the thalamus, where the fibers that conduct excitations from various sense organs approach each other and the transfer of excitations from one system to another can be carried out especially successfully. The phenomena of mutual stimulation and mutual inhibition of the functioning of the sense organs are of great practical interest in situations where it becomes necessary to artificially stimulate or suppress their sensitivity (for example, during flight at dusk in the absence of automatic control).

Another form of interaction between the sense organs is their joint work, in which the qualities of sensations of one type (for example, auditory) are transferred to another type of sensations (for example, visual). This phenomenon of the transfer of qualities from one modality to another is called synesthesia.

Psychology is well aware of the facts of "colored hearing", which turns on in many people and is especially clearly manifested in some musicians (for example, in Scriabin). So, it is widely known that we regard high sounds as “light”, and low ones as “dark”. The same applies to odors: some odors are known to be rated as "light" and others as "dark".

These facts are not random or subjective, their regularity was shown by a German psychologist Hornbostel, who presented the subjects with a series of odors and offered to correlate them with a series of tones and with a series of light shades. The results showed great consistency, and, most interestingly, the odors of substances whose molecules included more carbon atoms correlated with darker shades, and the smells of substances whose molecules included few carbon atoms, with lighter shades. This shows that synesthesia is based on objective (still insufficiently studied) properties of agents affecting a person.

It is characteristic that the phenomenon of synesthesia is not distributed equally among all people. It is especially clearly manifested in people with increased excitability of subcortical formations. It is known that it prevails in hysteria, can increase markedly during pregnancy and can be artificially induced by the use of a number of pharmacological substances (for example, mescaline).

In some cases, the phenomena of synesthesia are manifested with exceptional distinctness. One of the subjects with exceptional severity of synesthesia - the famous mnemonist Sh. was studied in detail by Soviet psychology. This person perceived the weight of the voice as colored and often said that the voice of the person addressing him was "yellow and crumbly." The tones he heard caused him visual sensations of various shades (from bright yellow to dark silver or purple). Perceived colors were perceived by him as "voiced" or "muffled", "salty" or crispy. Similar phenomena in more obliterated forms occur quite often in the form of a direct tendency to "color" numbers, days of the week, names of months in different colors.

The phenomenon of synesthesia is of great interest for psychopathology, where its assessment can acquire diagnostic value.

The described forms of interaction of sensations are the most elementary and, apparently, proceed mainly at the level of the upper trunk and subcortical formations. There are, however, also more complex forms of sensory interaction or, as IP Pavlov called them, analyzers. It is known that we almost never perceive tactile, visual and auditory stimuli in isolation: perceiving objects of the external world, we see them with the eye, feel them by touch, sometimes perceive their smell, sound, etc. Naturally, this requires the interaction of the senses (or analyzers) and is provided by their synthetic work. This synthetic work of the sense organs proceeds with the closest participation of the cerebral cortex and, above all, those “tertiary” zones (“overlapping zones”), in which neurons belonging to different modalities are represented. These "overlap zones" (we talked about them above) provide the most complex shapes. joint work analyzers underlying object perception. We will turn to the psychological analysis of the main forms of their work below.

You can often find expressions according to which man is the crown of nature. However, in such phrases, attention is most often paid to the word "crown", demonstrating the perfection of the species Homo sapiens, its undeniable advantages over other animals and the unique ability to transform environment. The idea that a person, despite his special position among other living beings, still remains a part of nature, usually fades into the background.

In contact with

Introduction

But completely discount the natural component of man- impossible. It appears with early years at the first stages of cognition of the world: color, taste, smell, sound - all this information that characterizes an object can be obtained by a person only through the senses. This process appears to be simple. One of the above characteristics affects a specific organ, which perceives the characteristic and transmits it to the brain for processing. It should be understood that taste or smell are primarily illusory categories that are registered in the form of images by the senses.

It is these images that arise in the process of sensory cognition that are called sensations. The brain, processing and interpreting the received image, turns it into a fact of consciousness - something that can be called a specific word.

The very existence of consciousness and, as a consequence, thinking is determined by the presence of sensations. Loss of functionality of one of the sense organs leads to a lack of necessary information. The consequences of this can be different: from memory impairment to irreversible deformations of the psyche. At the same time, the number and quality of images received by properly functioning sense organs increases. There is some sort of compensation going on. Another property of consciousness closely related to sensations is the creation of synesthesias: one sense organ provokes the formation of an image, for which usually another body is responsible. For example, when smelling a flower, a person imagines a flower visually or, having barely seen an apple, already imagines its taste.

The situations described above are only possible combinations of images received from different senses. In fact, each of them has its own specifics and properties, so it is impossible, for example, to confuse sound with taste.

But despite the significant differences in the types and properties of sensations, general characteristics can be identified:

It should be noted separately what ideas exist about the threshold of sensations in psychology. In addition to the purely utilitarian definition used to postulate a definition of the intensity of sensation, there are other consequences of the very fact of the existence of perceptual thresholds. One of the most important findings is that there is a clear relationship between the absolute lower threshold and analyzer sensitivity: the lower the threshold, the higher the sensitivity. This is easily explained: difficulties in obtaining the necessary information require the development of methods for obtaining it.

The last consideration is confirmed not only with the help of logical operations, but also with the data of science. Yes, it is established that the sense organs not only improved in the process of evolution, but also improved in ontogenesis ( individual development) of each individual. Of course, different analyzers have different sensitivities.

The ratio and implementation of the above characteristics of sensations depends on many factors. Not the last role in their combination is played by the age, health and conditions of the individual's activity. It is assumed that in absolute darkness a healthy young person is able to distinguish very weak light source(for example, a torch or a candle) at a distance of up to 27 km. With age or in the presence of diseases, this figure inevitably decreases.

The sense organs make it possible not only to register the presence/absence of a stimulus, but also to record differences in strength and intensity between two stimuli. This value is called the difference threshold and is relative. This is manifested in that in order to realize the change in the perception of the stimulus, it is required to make some increment to the latter, depending on the initial strength of the impact. Simply put, the greater the value of the initial irritation, the greater the increment to it is required.

Principles of classification of sensations

Availability common properties does not negate the variety of stimuli and a significant number of ways in which they affect the senses make it necessary to introduce various criteria for classifying them. The basis of the classification, depending on the goals pursued, both physiological and purely psychological criteria can be set. Since in both cases we are talking about the same sensation for the most part, both classifications are closely related to each other.

Classification by location and function of receptors

So, one of the classifications of sensations in psychology is based on the location of receptors and the nature of the reflection of the image they form:

1. Interoceptive. Their receptors are located in the internal organs and tissues of the body and directly reflect their condition. IN normal conditions the information transmitted by such receptors is beyond the lower threshold of sensitivity. This is a kind of first-class chemical laboratory: interoreceptors collect and transmit to the brain information about the presence or absence of both harmful and beneficial substances, determine the chemical composition of body fluids. In addition, it is the interoreceptors that notify the brain of changes in body temperature or pressure. In a critical situation, when malfunctions occur in the work of internal organs due to illness or any external cause, pain occurs.
2. Proprioceptive, the essence of which is the creation and subsequent transmission to the brain of an image about the position of the body in space and the movement it makes. This is done with the help of receptors located in the ligaments and muscles.
3. Exteroceptive sensations are focused on the perception and reflection of the properties of objects and phenomena of the external environment. Their receptors are located on the surface of the body and are divided into contact and distant. As the name implies, for the functioning of contact receptors, a direct effect of the stimulus on them (touch, taste) is necessary. Distant receptors receive information from a distant object and form sound, visual and olfactory images.

Of course, all the above types of receptors and the images they create do not exist in isolation from each other. Often, obtaining one sensation requires a complex of information collected by exteroceptors and interoceptors. For example, the idea of ​​the position of the body in space is not only created with the participation of proprioceptors, but is also inevitably supplemented by a visual image.

Another classification is based on the participation in the formation of sensations of various sense organs. To a large extent, the very concept of sensations became possible only due to the presence of these organs and the desire to understand the principles of their functioning. Accordingly, one can distinguish taste, visual, olfactory, tactile and auditory sensations.

Tactile sensations (touch) can be considered the leader in terms of the amount of information received and transmitted. This happens thanks to that touch involves both types of exteroceptors (located throughout the skin area) and, thus, can capture both touch and temperature.

The sense of smell provides a person with information about smells that played a huge role in the life of animals even in prehistoric eras. The great importance of the sense of smell is evidenced by the fact that the receptors perceiving smells are located on the protruding part of the body, and information about them is transmitted to the brain along the shortest and most direct trajectory.

Taste sensations There are four types: sweet, salty, sour and bitter. Based on these modalities, the whole palette of tastes is formed, just as the color scheme is made up of the basic red, yellow and blue. Taste is closely related to smell, since it is caused by the same molecules of a substance, but perceived by different receptors. It is easy to verify the existence of this connection by your own example: when the nose is stuffy during a cold, the taste of food either disappears altogether or changes completely.

visual

Visual sensations are caused by electromagnetic waves of a certain length. The human eye perceives only part of the spectrum: from red to purple. And although infrared and ultraviolet radiation have a significant impact on a person, you can only find out about this by the consequences. In complex visual sensations can be distinguished:

• achromatic (transition from absolute darkness to light through shades of gray);
• chromatic (reflect all colors of the gamut with their shades);

In psychology, it is noted that different colors and their combinations can have different emotional effects on a person. This fact is used in various tests (for example, the Luscher test).

Auditory

Auditory sensations are by their nature close to visual ones: they are also caused by waves of a certain range. Infra- and ultrasound remain beyond hearing. Sound is determined by timbre(in other words, the color of the sound), duration, height (depends on the frequency of the wave oscillations) and loudness (determined by the period of the wave oscillation). There are three types of sound sensations: noise, speech and music.