The meaning of the word "acoustics" in 9 dictionaries

In general, acoustics is the science of sounds. Sounds have always played a special role in the life of any person, as they allow people to navigate space, communicate, watch movies and listen to their favorite music.

Figure 1. Varieties of acoustics. Author24 - online exchange of student work

The use of acoustics is in demand in absolutely all areas, from construction to medicine. This scientific section studies the vibrations of sound waves, the principles of their formation and distribution.

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Definition 1

Acoustics is a broad field of physics that studies elastic vibrations and waves from the lowest frequencies to the highest.

A person begins to hear sound through constant vibrations produced at a certain frequency. One of the main definitions of acoustics is a sound wave, which is a vibration whose pressure directly depends on the source. For example, a car horn signal carries a higher vibration than a human whisper. Sound intensity is always measured in decibels.

Modern acoustics covers a fairly wide range of issues; it includes a number of important subsections:

physical acoustics - studies the features of the propagation of elastic waves in various spaces;
physiological acoustics - describes the structure and operation of sound-producing and sound-perceiving organs in humans and animals.

In a narrower sense of the word, acoustics should be understood as the study of sound, that is, elastic vibrations in gases, solids and liquids perceived by the human ear. A sound wave can be reflected from surfaces, scattered in them, or absorbed. The reflection parameter of the sound force is determined by what acoustic characteristics it has and what the sound wave has passed through.

Finished works on a similar topic

Course work The concept of acoustics in physics 410 ₽ Abstract The concept of acoustics in physics 250 ₽ Test work The concept of acoustics in physics 250 ₽

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The nature of sound and its physical characteristics

Figure 2. Physical characteristics of sound. Author24 - online exchange of student work

Sound waves and vibrations are a special case of mechanical changes. However, due to the importance of acoustic definitions for the correct assessment of auditory sensations, as well as because of the medical application, it would be advisable to examine some issues in more detail.

Today it is customary to distinguish the following sounds:

tones, or musical sounds;
noises;
sonic booms.

Tone is a periodic process of sound. If this process is completely harmonic, then the tone is called pure or full, and the corresponding sound plane wave is described by the corresponding equation. The key physical characteristic of this type of sound is frequency. Anharmonic vibration corresponds to a complex tone. A simple tone is formed, for example, by a tuning fork, but a complex tone can be heard thanks to musical instruments.

The lowest frequency of decomposition of a complex tone into simpler structural units corresponds to the fundamental tone; the remaining overtones in this case have frequencies equal to $2νο$, $3νο$ and so on.

Definition 2

A set of vibrations with an indication of their specific intensity (amplitude A) is called an acoustic spectrum in physics.

The spectrum of a complex tone is always lined. Thus, the acoustic spectrum is one of the most important physical characteristics of musical sounds, since it can be distinguished by a complex, non-repeating time dependence.

Researchers include noise from car vibrations, applause, rustling, burner flames, creaking, consonant sounds of speech, and so on. This sound type can be considered as a combination of chaotically changing complex tones

Definition 3

A sonic boom is a short-term, uniform sound impact in the form of an explosion or pop.

A sonic boom should not be confused with a shock wave, the frequency of which is much higher.

Main directions of modern acoustics

Numerous scientific works on the study of the nature of noise and the issues of noise reduction and sound insulation were published some time later. The first work in this area concerned mainly the noise produced by aircraft and ground transport. But over time, the boundaries of these studies have expanded significantly. At the moment, most industrialized countries have their own research institutes that are engaged in developing solutions to these problems.

Today, the following sections of acoustics are best known: general, geometric, architectural, construction, psychological, musical, biological, electrical, aviation, transport, medical, ultrasound, quantum, speech, digital. The following chapters will examine some of these areas of sound science.

Wave nature of sound

Figure 3. Wave nature of sound. Author24 - online exchange of student work

To better define the system for the appearance of a sound wave, it is necessary to imagine a classic speaker located in a pipe, which is filled to the brim with air. If this device suddenly moves forward, the air in the immediate vicinity is compressed for a moment. After this, the air gap will expand, pushing the compressed area of air along the pipe.

It is this wave motion that will subsequently become sound when it reaches the auditory organ and “excites” the eardrum. When a sound wave occurs in the gas, excess internal pressure and unnecessary density are formed and particles are transformed at a constant speed. When studying sound and its features, it is important to remember the fact that material matter does not move in proportion to the sound wave, but only a temporary disturbance of the acting air masses appears.

Note 1

If the particles vibrate along the direction of wave propagation, then the wave sound is called longitudinal, but if they vibrate directly perpendicular to the direction of wave propagation, then the wave is called transverse.

Typically, sound tones in liquids and gases are longitudinal, but in solid physical bodies the formation of waves of both types is possible. Transverse waves in material bodies arise through resistance to changing the original shape. The key difference between these two types of waves is that the transverse wave is equipped with the property of polarization, while the longitudinal wave is not.

Anecdote from life

Nevertheless, even at present, not all manufacturers of industrial equipment pay at least some attention to this issue. The management of not all plants and factories is concerned about maintaining healthy hearing among their subordinates.

Sometimes you hear stories like this. The chief engineer of one of the large industrial enterprises ordered the installation of microphones in the noisiest workshops, connected to loudspeakers located outside the buildings. In his opinion, in this way the microphones will suck some of the noise out. Of course, as comical as this story is, it makes you think about the reasons for such illiteracy in matters relating to noise reduction and sound insulation. And there is only one reason for this - in educational institutions of higher, secondary vocational and secondary specialized levels of education, only in recent decades have they begun to introduce special courses in acoustics.

Professional societies

Acoustical Society of America (AS)
Australian Acoustical Society (AAS)
European Acoustical Association (EAA)
Institute of Electrical and Electronics Engineers (IEEE)
Institute of Acoustics (IoA UK)
Audio Engineering Society (AES)
American Society of Mechanical Engineers, Noise and Acoustics Division (ASME-NCAD)
International Commission on Acoustics (ICA)
American Institute of Aeronautics and Astronautics, Aeroacoustics (AIAA)
International Computer Music Association (ICMA)

Acoustic scale

Hypersound is elastic waves with frequencies from 101000 to 1012-1018 Hz. By its physical nature, hypersound is no different from sound and ultrasonic waves. Hypersound is often represented as a stream of quasiparticles - phonons

In nature, it is generated by vibrations of atoms at the sites of a crystal lattice, and its wavelength is equal to the average path of a molecule before it collides with another.

Ultrasound - with a frequency greater than 20 kHz.

Normal sound (audible to the human ear) is from 20 Hz to 20 kHz.

Infrasound - with a frequency of less than 20 Hz.

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