CC BY
0PHYSICAL CHARACTERISTICS OF SOUNDS USED IN
MEDICINE
Urmanova G.U.
Assistant professor of Tashkent Pediatric Medical Institute https://doi.org/10.5281/zenodo.13627331
Abstract. Acoustics (from Greek, asiosustus - to hear, I hear) is the study of elastic vibrations and waves, starting from low-frequency vibrations to extremely high (1012-1013 Hz) frequencies. Nowadays, there are several departments of acoustics. Including physical acoustics, technical acoustics, physiological (bio) acoustics and hydroacoustics.
Keywords: sound, audiometer, acoustics, process, frequency, timbre, mechanism, ear.
Currently, acoustics are distinguished by the following:
- Physical acoustics studies the laws of propagation of waves in various environments -atmosphere, water, earth, gas, liquid, solid bodies, etc. and their interaction with matter.
-Technical or applied acoustics includes construction and architecture, electroacoustics, acoustoelectronics, and acoustooptics. Technical acoustics studies noise and vibrations of various origins.
- Special departments of acoustics, bioacoustics or physiological acoustics, explain the structure, function, working mechanism, physical characteristics, etc. of the sound reception and hearing systems of living organisms, i.e. humans and animals.
- Hydroacoustics studies the phenomena of sound waves, propagation and reception in the water environment.
Elastic vibrations and waves with a frequency of 16 Hz to 20,000 Hz that can be perceived by the human ear are called sound. Sound sources are natural and artificial, and examples of them include:
Natural sound sources create objects and natural phenomena, for example, the singing of birds, the sound of a waterfall, the sound of rain, the sound of thunder, the hum of bees, the human speech apparatus, etc.
Artificial sound sources are invented by man, for example, doors creaking, children's voices, musical instruments, airplanes, cars, porcelain crystals, tuning fork sounds, etc.
Sound is measured by the sound vibrations, mechanical vibrations and waves that the hearing system can absorb. Therefore, the study of acoustic concepts is of great importance in elucidating the auditory perception of living systems. For this purpose, that is, to study their application in medicine, we will consider some issues.
According to the degree of hearing of sounds of the auditory system, it is accepted to distinguish them from each other, for example:
□ Tones or musical sounds;
□ Noises;
□ Sound beats etc.
□ Tones or musical sounds. A sound consisting of periodic processes is called a tone, if this process is harmonic, then the tone is called simple or pure.
□ The main physical characteristic of a pure tone is its frequency. If the process is anharmonic, such a tone is called a complex tone. The complex tone itself is divided into simple
or simple tones. A simple tonal sound is produced, for example, by a tuning fork, and a complex tonal sound is produced by musical instruments, speech apparatus (vowel sounds) and frequencies (Fig. 1).
Royal
Clarinet
Fig. 1.
Sound can be represented as a sum of harmonic vibrations with different frequencies and amplitudes. The smallest frequency of the separated tones corresponds to the fundamental tone, and the remaining harmonics (overtones) have specific (2v0, 3v0....) frequencies. A set of frequencies indicating relative intensities or the frequency dependence of the amplitude (or effective value) of the harmonic components of a sound wave is called the acoustic spectrum of sound.
Acoustic spectrum is an important physical characteristic of a complex tone. Figure 2 shows the oscillograms of sounds of the same pitch played on a grand piano and a clarinet. The two oscillation periods are the same, but they are very different in their shape and therefore in their harmonic composition.
The complex tone spectrum is linear. Fig. 2. shows the spectra of the audio signals given in Fig.1. Since the sounds have the same pitch, the frequencies of the tone - the fundamental and the harmonics - are the same. However, the amplitudes of the individual harmonics in each spectrum vary greatly.
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0
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I I I II
1.0
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0 400 800 1200 1600 1800
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0 400 800 1200 1600 1800
frequency
Fig. 2.
Based on the above, it can be said that the acoustic spectrum represents an important physical characteristic of a complex tone.
□ Noises. A sound that does not repeat itself over time and is characterized by its complexity is called noise, and it includes the vibration of cars, the sounds of loud applause, the
noise of a burner flame, a ghost, the rattling of doors, the consonant sounds of speech, etc. Noise consists of a combination of complex tones that change irregularly. Continuous broadband is characterized by audio signals that have changed over time, called noise. At the same time, according to the position of the maximum spectrum, noise can be divided into low frequency (maximum below 300 Hz), medium frequency (from 300 to 800 Hz) and high frequency (above 800 Hz).
□ A sound shock is a short-term effect of sound, an acoustic phenomenon in the form of an explosion that occurs when shock waves are emitted from a supersonic object in the atmosphere. In this case, only when the wave reaches the observer, the sound of the shock is heard. For example, sounds from thunder and meteorites, clapping, explosions, etc. When the shock wave reaches the earth's surface, the increase in pressure in its front affects the eardrum and is perceived as a strong and loud sound.
Physical parameters of sound based on the above:
• Sound spectrum;
• Sound intensity;
• Sound duration;
• Speed of sound;
• Volume, etc.
In order to realize the sense of hearing or perception of sound, our brain must analyze the properties and characteristics of sound. The intensity, that is, the strength of the sound, is characterized by how high or low this sound is. The pitch of the sound is divided into high and low sounds depending on the frequency of this vibration.
Since sound hearing sensations are objective, it is also evaluated subjectively by a person. When hearing tones, a person distinguishes them by their pitch. Loudness is a subjective characteristic of the sound, conditioned primarily by the frequency of the fundamental tone.
Loudness is another subjective assessment of sound that characterizes the level of hearing sensation. Weber-Fehner's law is used to create a scale of loudness levels. Weber-Fehner's law is a psychophysiological law in which the intensity of perception is directly proportional to the logarithm of the intensity of the stimulus.
In order to distinguish it from the scale of sound intensity, decibels in the sound intensity scale are called background. At other frequencies, the test sound is compared to a sound with a frequency of 1 kHz to measure the loudness. For this, a sound with a frequency of 1 kHz is generated using a sound generator. The intensity of a sound with a frequency of 1 kHz, measured in decibels using the instrument, is equal to the loudness of this sound expressed in the background. In order to find the correspondence between sound intensity and loudness at different frequencies, it is accepted to use curves of equal loudness value.
Everyone can lose hearing due to various diseases, for example, pathologies, age-related changes and other factors. It is very important to identify them at an early stage and to treat them effectively. Ignoring the problem can lead to complete deafness. Everyone experiences the onset of hearing loss in their own way and tries to find a solution. The best way to do this is audiometry.
The method of audiometry (from the Latin I hear, hearing and Greek metron measure; acumetry (from the Greek akuo - I hear)) is a measurement of hearing acuity, determination of hearing sensitivity, etc..
There are the following main types of audiometry:
- Acumetry - determines the perception of whispering and spoken speech;
- Tonal threshold audiometry - conducts a differential diagnosis of existing hearing impairment;
- Speech audiometry - determines the ability to convert sound signals into coherent speech;
- Approximate audiometry (performed in children under 3 years old);
- Play audiometry (children from 3 to 5 years old).
The method of determining the sound hearing acuity of the auditory system is called audiometry. The basis of the method is to determine the sensitivity of the hearing analyzer to sound waves of different frequencies, which requires much less time than other methods, while this audiometry is a safe and completely painless diagnostic method. Currently, for this method, audiometers of various shapes and sizes, which are recognized all over the world, are used. An audiometer is an electroacoustic device for accurate measurement of hearing acuity.
Nowadays, modern electroacoustic equipment is widely used all over the world, which allows to determine the limit of patient's hearing threshold. Such modern methods and devices detect diseases of hearing organs at the initial stage and prevent the appearance of pathologies. Since the method is safe, it can also be used in newborns.
A curve obtained by audiometry, that is, an audiogram, is a graphic representation of patient's auditory sensations. The difference between patient's audiogram and the curve of the healthy hearing threshold makes it possible to identify hearing disorders. Audiometry is not recommended if the patient is mentally ill, has abnormal behavior in the body, etc.
In conclusion, it can be said that methods based on sounds contributing to the development of medicine are unique. A person who is not indifferent to his health, in any case, it is better to get doctor's recommendation.
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