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:
‘Akoustikos’, which means ‘of or for the hearing/ready to hear’
‘Akoustos’, which means ‘heard or audible’.
Acoustics is the arm of science that deals with the 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 gases) and also with the following things:
Ultrasound and Infrasound
We define Acoustic as the science of sound, including its production, transmission, and effects involving biological & psychological effects.
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 the noise. To control these unpleasant/chaotic sounds, we must understand the importance of acoustics.
The techniques/methods we use to absorb undesirable sounds by using soft-porous surfaces are 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
The conditions for good acoustics are:
Syllable - The syllable should be loud.
The Time Between Two Syllables - It should be least. It means that the reflection of the previous syllable should be minimum so that the next syllable is audible.
Echo - The adjustment of echoes should be minimum so that the continuity of sounds doesn’t get affected.
Hall - The windows of the building should be opened and must have absorbing surfaces to avoid the prolonged reflection of the sound.
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.
The types of acoustics with their explanation are as follows:
Vibrations & Dynamics
We have seen multistorey 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.
These acoustics help reduce the noise created in an environment by different modes of transport.
The frequency of infrasounds is less than 20 Hz. They are not audible to human ears.
Infrasounds are useful in the following ways:
Detecting the probability of earthquakes.
Noticing petrol formation in a particular area.
The frequency of the ultrasound is greater than the human audible limit. The areas where we use the ultrasound is as follows:
In Ultrasound imaging in physics
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:
We may find the application of acoustics in almost all aspects of modern society, especially in the audio and noise control industries. So, 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, we use it in many fields; these are as follows:
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 the acoustic energy as the energy concerned with mechanical vibrations from its components.
Question 1: Write the stages involved in the Acoustics event.
Answer: The following are the three stages involved in the acoustic event:
Acoustic Wave Propagation (AWP)
Question 2: Write the names of real-life Acoustics devices.
Answer: We may find the following applications of Acoustics devices:
CD (Compact Disk) Players
Question 3: How can I make my room good Acoustics?
Answer: The following are simple solutions for making room good acoustics:
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
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.
Question 4: Define the term Reverberation.
Answer: 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 the reverberation.