Dhristi JEE 2022-24

What is Acoustic?

In our day-to-day life, we normally distinguish between sound and noise. In short, we refer to pleasant sequential impressions as sound, while chaotic or obstructive sounds are considered noise. 

There is a fine line between the sound and the noise. For reducing the noise, a sound-absorbing material is helpful. For studying how sound transmission takes place and how to control the noise, we will learn Acoustics. Now, let’s understand what acoustics is.

The word ‘Acoustic’ is derived from the following Greek word: 

  1. ‘Akoustika’, which means ‘of or for the hearing/ready to hear’

  2.  ‘Acoustic’, which means ‘heard or audible’. 

Acoustics Physics

Acoustics is the arm of science that deals with production, control, transmission, reception, and sound effects. In simple words, acoustics deals with the process of generation, reception, and propagation of sound.

It is that branch of physics that serves the study of mechanical waves in the states of matter (solid, liquid, and gasses) and also with the following things: 

  • Sound 

  • Vibration 

  • Ultrasound and Infrasound

Define Acoustic

We define Acoustic as the science of sound, including its production, transmission, and effects involving biological & psychological effects.

Sound Acoustics

We define sound as the elastic molecular fluctuations in the air or other media that generates a chain reaction (or vibration) by putting the nearest particle in motion. 

If the mixture of sounds creates an unpleasant impression, it becomes hard to distinguish individual sounds with a short reverberation time; such a type of sound is considered noise. To control these unpleasant/chaotic sounds, we must understand the importance of acoustics.

Importance of Acoustics

The techniques/methods we use to absorb undesirable sounds by using soft-porous surfaces is called acoustic protection. 

For example, you are working in the steel industry, and machines are producing large noises. To reduce this noise, what you can do is, insert any soft material into the valves of the machine, then the noise from that machine minimizes. It’s because the smooth and plain surfaces produce large noise and soft-porous materials avoid the echoing of the sound because of which the sound-level reduces. That’s why porous materials are used in noise control industries.

Conditions for Good Acoustics

The conditions for good acoustics are: 

  1. Syllable - The syllable should be loud.

  2. The Time Between Two Syllables -  It should be the least. It means that the reflection of the previous syllable should be minimum so that the next syllable is audible. 

  3. Echo - The adjustment of echoes should be minimum so that the continuity of sounds doesn’t get affected. 

  4. Hall - The windows of the building should be opened and must have absorbing surfaces to avoid the prolonged reflection of the sound. 

  5. Reverberation - Reverberation means the reflection of the sound. The reflection of the sound should not be small because if it dies before reaching to ears, then the continuity of sounds gets affected. Such a type of condition in which the reflection of sound dies is called the Dead Hall Effect. 

Types of Acoustics

The types of acoustics with their explanation are as follows: 

  • Vibrations & Dynamics

We have seen multi-story buildings in big cities like Mumbai many times. These buildings are set up (constructed) in such a manner that they absorb earthquakes. The reason is, vibrational controls are installed in these buildings to protect the buildings from these shocks. These controls are used to ground vibrations in railways. 

  • Environmental Acoustics

This acoustics help reduce the noise created in an environment by different modes of transport.

  • Infrasounds

The frequency of infrasounds is less than 20 Hz. They are not audible to human ears. Infrasounds are useful in the following ways: 

            1. Detecting the probability of earthquakes. 

            2. Noticing petrol formation in a particular area.

  • Ultrasounds

The frequency of the ultrasound is greater than the human audible limit. The areas where we use ultrasound are as follows: 

            1. In Ultrasound imaging in physics 

            2. Detecting objects M

            3. Measuring distance 

  • Musical Acoustics 

We study musical acoustics to understand how sounds are used to create any music. The places we use musical acoustics include the following areas of study:

            1. Musical Instruments

            2. Music therapy

            3. Human voice

Applications of Acoustics

The application of acoustics is the proper transmission of sound. Initially, the acoustics were used as a noise-controlling device in industries only. However, at present, use in many fields; these are as follows: 

  1. Architectural industries

  2. Medicine

  3. Warfare


Acoustic Energy

Acoustic energy is the disturbance of energy, which passes through a material in the form of waves. An example of acoustic energy is sound energy. When sound travels through any medium, it produces vibrations in the form of waves. In other words, we can define acoustic energy as the energy concerned with mechanical vibrations from its components.

Acoustics - A Branch of Science Dealing with Sound

Sound also called acoustics is a form of energy that can be transmitted from one place to another. Sound is a very important part of our existence. Sound is one of the primary ways by which living beings communicate with each other. In our daily lives, we hear various sounds from both living and nonliving things. How can we hear this sound? How is the sound produced? all these questions arise in our minds. Sound is produced when an object Is in motion. For example, when the strings of a guitar, the skin of a drum, the Hanging ball of a bell vibrate, they produce sound. When we talk, if we place our fingers on our throat we can also feel vibrations. When a bell is struck, not only do we hear the sound of the bell but also if you place fingers on a moving bell our hands start shaking. These are examples of vibrations that are produced by sound. A sound is a form of pressure wave created by the vibration of an object. 

In this article, let us study acoustics and types of acoustics in detail.

Science deals with the study of sound, how it is produced, how it is transmitted, its sources, properties, and effects.

Acoustics is the study in physics that deals with the study of sound waves in glasses, liquids, and solids. Initially, acoustics was used only in industries that are based on sound like an auditorium, theater but today, the use of acoustics has spread to numerous areas.

The acoustic wave equation is the fundamental equation that describes sound waves propagation. In liquids, Sound spreads in the form of pressure waves, and in solids, they spread in the form of long length waves or transverse waves.

There are three categories of sound waves: longitudinal or long length waves, mechanical or self-regulatory waves, and pressure waves.

Characteristics of Sound Waves

  • Frequency. 

  • Amplitude. 

  • Timbre. 

  • Envelope. 

  • Velocity. 

  • Wavelength. 

  • Phase.

  • Loudness

  • Pitch

We can see various waves in the diagram below.

(Image will be uploaded soon)

Acoustic Instruments

Any instrument having strings whether they are made of wood or brass is acoustic in nature. Some instruments which are acoustic in nature are pianos, violins, guitars, clarinets, etc. 

Branches of Acoustics

  1. Archaeoacoustics – the study of sound within archeology. 

  2. Aeroacoustics – the study of noise generated by air movement

  3. Architectural acoustics – the science of how to achieve a good sound within a building.

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FAQs (Frequently Asked Questions)

1. What are the types of Acoustics?

Types of acoustics are:

  • Environmental Noise: Environmental Acoustics is involved with vibration and noise created by vehicles on roads and trains running on tracks. 

  • Musical Acoustics: Musical acoustics are related to the study of music. It studies how sound waves get transformed into music.

  • Ultrasounds. 

  • Infrasounds. 

  • Vibration and Dynamics.

2. In which fields are acoustics applicable?

Acoustics is an extensive branch of science that discovers its application in almost every existing field. Some of the major fields where acoustics are applied are:

  • Medicine

  • Warfare

  • Architectural industries

  • Music

  • Geologic

  • Study underwater and atmospheric phenomena

  • Noise control industries

  • Detection of petrol under the Earth

  • Detection of earthquakes

3. Can we find acoustics in space?

No, you cannot hear any sounds in space because it is empty as there is a vacuum there. Sound only travels through a medium like solids, liquids, or gasses through a medium (such as air or water). In space,  only a vacuum is present and in the absence of air, sound has no way to travel.

4. Is acoustic a modern technology?

Yes, Acoustics is the branch of physics concerned with the study of sound (mechanical waves in gas, liquids, and solids). Acoustic technology includes fields like music, study of geologic factors of Earth, atmospheric, and underwater events.

5. How can you apply acoustic in daily life?

There are various acoustical devices around you: telephones, and television sets at home, compact disc and tape recorders, and even clocks that talk and have music tones are common examples of the application of acoustics. Hearing aids that are used by physically challenged people are the best examples of acoustical devices.

6. Can we prepare acoustic materials?

Yes we can produce acoustics materials which are useful in homes as well as at workplaces. some examples of acoustic material are:

  • Mineral wool

  • Sealant

  • Wood wool

  • Syntactic foam.

  • Wood-plastic composite..etc

7. Write the stages involved in the Acoustics event.

The following are the three stages involved in the acoustic event:

  1. Generating Mechanism

  2. Acoustic Wave Propagation (AWP)

  3. Reception Effect

8. Write the names of real-life Acoustics devices.

We may find the following applications of Acoustics devices:

  • Telephones

  • Radios

  • Television Sets

  • CD (Compact Disk) Players

  • Tape Recorders

  • Speaking Clocks

  • Hearing Aids

9. How can I make my room good Acoustics?

The following are simple solutions for making room for good acoustics:

  • Sound Masking

We can play white noise so that outside noise doesn’t disturb us during our studying hours. 

  • We may also use soundproof drywall or soundproof curtains as an alternative.

  • Acoustic Ceiling Tile

  • Acoustic Foam

  • Hanging Baffles

  • Acoustic Partitions

  • Hang textiles and wall art on parallel walls to reduce the noise effect.

  • Use acoustic panels to increase sound absorption.

  • Use a tall bookcase in our room and add many objects inside the room to minimize the impact of environmental noise in our room.

10. Define the term Reverberation.

When the sound hits the hard surface, it continues to reflect until it loses its energy and dies (called the death hall effect). The elongated reflection of the sound waves is called reverberation.