Sound Meaning for Class 4 Maths

Sound is an essential part of our daily life. Here, students will learn the sound meaning. Also, they will get information about sound frequency, properties of sound, what is the speed of sound, etc. this content also includes the mathematical concept of addition, subtraction, multiplication, division, tally marks, etc.

Properties of Sound

Sound is vibration; we can represent sound using a diagram, a shape like a mountain and a valley. Sound is measured in Hertz.

The sounds’ speed varies depending on some parameters, so it is not constant, and it changes according to

• Temperature
• Medium of travel (solid, liquid, gas)
• Humidity of air

Sound Frequency:

The vibrations in every sound are called Frequency, the waves number in one second.

For example, if ten waves are complete in one second, then the Frequency of the sound is 10 Hz (Hertz).

What Is the Speed of Sound?

The distance travelled by sound per unit of time through the medium is called the speed of sound.

Speed of Sound Formula:

We know that,

Speed=
Speed=

In the case of the sound wave,

Distance = Wavelength

and =Frequency
Also,Time=

So, the formula for the speed of sound becomes,

Speed = Wavelength * Frequency

From this formula, we can say that,

Wavelength=
and Frequency

Sound requires a medium to travel.

Example:

• The sounds’ speed in the air is 346 m/s.
• The sounds’ speed in water is 1531 m/s.
• The speed of sound in iron is 5950 m/s

Hearing Range:

Sonic Sound In this range, the sound frequency lies in the field of 20 Hz to 20,000 Hz. It is the human hearing range.

Infrasonic Sound In this range, the sound frequency is less than 20 Hz.

Ultrasonic Sound The sound frequency is greater than 20,000 Hz in this range.

Hearing Range Table:

Organism	Hearing Range
Human being	20-20,000
Elephant	16-12,000
Cow	23-35,000
Rat	200-76,000
Bat	2,000-110,000
Horse	55-33,500
Dog	67-45,000
Rabbit	360-42,000

As humans grow, their hearing also changes:

• Childhood: 15 Hz - 15,000 Hz
• Adult age: 20 Hz - 20,000 Hz
• Old age: 50 Hz - 8,000 Hz
• Most sensitive range: 1,000 Hz - 4,000 Hz

Operations on Real Number

Question 1:

Puja Is Going to Visit a Forest With His Father. In This Forest, an Elephant Produces a Sound With a Frequency of 15 Hz. Assuming the Speed of Sound in Air Is 450 m/S, Determine the Wavelength of This Sound Wave.

Answer 1:

Frequency of the sound = 15 Hz
Speed of sound = 450 m/s
Then from the formula of the speed of sound, we have,

Speed = Wavelength × Frequency
From this,

Wavelength
Wavelength m

Wavelength = 30 m

The wavelength of the sound is 30m.

Question 2:

Raja Is Going to Visit a Zoo With His Father. In This Zoo, a Tiger Produces a Sound With a Frequency of 20 Hz. Assuming the Wavelength of This Sound Is 25 m, Determine the Speed of Sound in the Air.

Answer 2:

Frequency of the sound = 20 Hz
Wavelength = 25 m
Then from the formula of the speed of sound, we have,
Speed = Wavelength × Frequency
Speed = (25 × 20) m/s
Speed = 500 m/s
The speed of the sound in the air is 500 m/s.

Question 3:

On a Hot Summer Day, a Pesky Little Mosquito Produced Its Warning Sound Near Your Ear. The Beating of Its Wings produces the Sound. Assuming the Speed of the Sound Is 300 m/S and the Wavelength of the Sound Wave Is 10m, Determine the Frequency

Answer 3:

The wavelength of the sound wave = 10 m
Speed of sound = 300 m/s
Then from the formula of the speed of sound, we have,
Speed = Wavelength × Frequency
From this,

Frequency=
Frequency= Hz

Frequency = 30 Hz

So, the Frequency of the sound is 30 Hz.

Tally Marks Question

Question 4:

The School Has Arranged an Excursion to Zoo for Grade 4 Students. In That Zoo, a Tally Chart Is Present on the Wall.

The Tally Chat Is Given According to the Hearing Range of the Organism.

The Tally Chart Is:

Hearing Range	Tally Marks
16-12,000
55-33,500
67-45,000
360-42,000
200-76,000

Convert the Tally Chart With Organism Names According to the Hearing Range and Tally Marks Into Numbers.

Answer 4:

Organism	Number
Elephant	25
Horse	19
Dog	22
Rabbit	26
Rat	38