Ear, The Way We Hear Sound, How The Sound Enters Into Ear, Chapter 27 (1)

[ ইংরেজীতে প্রকাশিত করা হল কিছু কিছু বাংলাদেশী বংশোদ্ভূত বিদেশে অবস্থানরত ছাত্র/ ছাত্রী পাঠকেরা যারা বাংলা ভাষা পড়তে পারেনা, তাদের অনুরোধে, দুখিত ]

 What is “sound”?
Sound is an energy that remains always beyond our vision. Light is also an energy but we can realize it only with our eyes. Sound requires atoms or molecules of particle (solid, liquid or gaseous) to travel.

But light 0r radiation do not require any media to travel.
HOW IS SOUND GENERATED?

A sound Is generated if waves are produced in a particle either solid, liquid or gaseous. When any energy produces wave on any particle, it spreads all around in our environment.

Suppose you throw a rock on the water in a pond, it produces waves on water that spreads all around.

Same way, if you strike on the leather of a drum, it produces waves in air that transmit all around.( click on the link in Figure-1, )

Source of figure- http://www.dosits.org/images/dosits/drumset.gif

Figure-1, you can see how the waves spread all around clicking upon figure 1.
The distance between the highest crest of 2 waves is called WAVE LENGTH.

See the figure- 2 below-

Source of figure- http://tellmewhyfacts.com/2007/09/how-does-sound-travel.html

Figure-2, the wave length in air.

HOW MUCH IS THE SPEED OF SOUND-WAVES?

The speed of sound- wave varies upon temperature and concentration of the media.

On the sea surface of the earth at 15⁰ Celsius the speed of sound is 761.20 miles per hour (1)

The sound-waves enter into our ear from outside. See figure-3

Source of figure- http://tellmewhyfacts.com/2007/09/how-does-sound-travel.html

Fiure-3, look, how the sond-waves are entering into our ear.

We are to remember, sound wave cannot generate or travel without any media either solid,liquid or gaseous.

But the light or radio wave don’t require any media to travel.
This is why, we cannot make listened anyone our voice at an altitude higher than 300 miles above the earth surface, where there is no air.

The space scientists, in this area, talk each other and manage their works using radio headphone.

But there is air in the Space Station.

Above you have seen the sound-wave has already entered into our ear.

Ok, then have we already listened the sound?
Not al all.

To hear and understand the sound, this gaseous wave to transduce into electric wave and to reach at AUDITORY CENTER in TEMPORAL LOBE of brain through Auditory nerve. See figure -4.

Then another part of the brain analyzes and recognizes the significance of the sound if it is a song, roar of a tiger, from your allied or enemy party?
Human ear has capability to catch a particular limited range of wave frequency. Similar happens with other animals also. Human cannot listen what a dog can listen. (10)

Source of figure- https://www.quora.com/Which-parts-of-the-brain-control-which-human-behaviours

Figure-4, The Brain, look the Auditory Center. (Hearing Center)

But the question is, who will transduce this gaseous wave into electric wave? Or will it occur magically?
No, There happens nothing magically.

This is our inner ear that transducs the gaseous wave into electric wave and transmits to the Auditory Center in brain. See figure-3

To perform this action perfectly, the ear has 3 parts, as-

1. EXTERNAL EAR.
2. MIDDLE EAR.
3. INNER EAR.

It will be better to state beforehand that the inner ear has 2 kinds of function-

1. FUNCTION OF LISTENING- in this part, the entered air waves are transduced into electric wave.
2. FUNCTIONS OF BODY BALANCES- an adjacent part maintains the body balances. (1-10)

It will continue.

Please click here to see the past chapters- https://chkdr02.wordpress.com/

Updated on- 5/30/2017

References of 27^th Chapter
1) SOUND SPEED
http://www.livescience.com/37022-speed-of-sound-mach-1.html
2) http://en.wikipedia.org/wiki/Ear
AUDITORY & VESTIBULAR PATHWAYS
3) http://www.bioon.com/bioline/neurosci/course/audvest.html
4) HAIR CELL
http://www.ncbi.nlm.nih.gov/books/NBK11122/
5)VESTIBULE & COCHLEA
http://www.cochlea.eu/en/ear/inner-ear
6) VESTIBULE
https://www.boundless.com/biology/sensory-systems/hearing-and-vestibular-sensation/transduction-of-sound/
7) FUNCTION OF SEMICIRCULAR CANAL
http://www.healthline.com/human-body-maps/semicircular-canals
8)FUNCTION OF INNER EAR
http://www.healthline.com/human-body-maps/semicircular-canals
9)How sound travel
http://www.tellmewhyfacts.com/2007/09/how-does-sound-travel.html

10) http://tellmewhyfacts.com/2007/09/how-does-sound-travel.html