Sound as longitudinal vibrations of air

In summary, sound is created through longitudinal vibrations of air, which are detected by the ear. Humans produce sound through the vibrations of their vocal cords, located in the neck. Sound can be heard even if someone is standing behind the source due to the diffraction of sound waves through the nose and mouth. The intensity of sound is reduced when standing 1 meter behind the source compared to 1 meter in front. Sound waves interfere in a similar manner to light waves, and can still be heard even at points of interference. Despite closing the mouth and plugging the nose, sound can still be produced by puffing out the cheeks and humming. This suggests that complete closure of the mouth and nose is not necessary for sound production.
  • #1
pivoxa15
2,255
1
Sound is just Longitudinal vibrations of air that are detected from objects like the ear. Hence it originates from a vibrator.

For humans this vibrator is in the neck in the form of a vocal cord. So sound from humans really comes from the neck and the vibrations of air ascend up the neck and comes out from our mouth and nose.

The question is I am able to hear someone's voice even if I am right behind them. Does this occur because of the diffraction of sound which is a wave as it passes through that person's nose and mouth? What is the difference in intensity of sound between someone standing 1m in front and 1m behind a person producing sound?

Another question is sound waves interfere just like any other wave but when minima occurs, the sound dosen't neccessairly cancel (i.e. you would still hear some sound? Whereas light would, ie. dark fringes.
 
Last edited:
Physics news on Phys.org
  • #2
It's not necessarily a diffraction through their nose and mouth. Keep in mind also that air is not the only carrier of sound waves. If I close my mouth and plug my nose, I can still make audible noises.

Air diffracts sound quite a bit, and the room you're in probably reflects sound fairly well. Both of these are the reason that sound spreads in many directions.
 
  • #3
Just like light, you can consider every point on a sound wave a source of new waves. The sound diffracts through the air.

Sound waves do interfere exactly like light. I have been in orchestra halls where in some seats you could hear almost nothing. Similarly, those fringes are where the intensity is reduced, not where there is no light.
 
  • #4
KingNothing said:
If I close my mouth and plug my nose, I can still make audible noises.

When I try to do that, whenever I make a sound, it's because I haven't closed my mouth and or nose properly. When they are completely shut, isn't sound from the vocal cord impossible?
 
  • #5
pivoxa15 said:
When I try to do that, whenever I make a sound, it's because I haven't closed my mouth and or nose properly. When they are completely shut, isn't sound from the vocal cord impossible?
You can puff your cheeks out while your mouth is shut and your nose is plugged, right? Try humming as you puff them out.
 
  • #6
Hurkyl said:
You can puff your cheeks out while your mouth is shut and your nose is plugged, right? Try humming as you puff them out.


Again when I make a hum noise, it's because I haven't closed by mouth or nose properly.
 

What is sound?

Sound is a form of energy that travels through longitudinal vibrations of air particles. It is created when an object vibrates and causes the air particles around it to vibrate, creating a series of compressions and rarefactions that travel through the air as a sound wave.

How does sound travel?

Sound travels through air as a longitudinal wave, which means the particles of the medium (air) vibrate in the same direction as the wave is traveling. This vibration creates areas of high pressure (compressions) and low pressure (rarefactions), which propagate through the air until they reach our ears.

What factors affect the speed of sound?

The speed of sound is affected by three main factors: temperature, density, and elasticity. In general, sound travels faster in warmer temperatures, denser mediums, and more elastic mediums. For example, sound travels faster through solids than through liquids or gases.

How does sound get produced?

Sound is produced when an object vibrates, causing the air particles around it to also vibrate. These vibrations create pressure waves that travel through the air until they reach our ears. The pitch and volume of the sound are determined by the frequency and amplitude of the vibrations.

What is the difference between pitch and volume?

Pitch refers to the frequency of a sound wave, or how fast the sound wave is vibrating. A higher frequency creates a higher pitch, while a lower frequency creates a lower pitch. Volume, on the other hand, is determined by the amplitude of the sound wave, or how much energy it is carrying. A higher amplitude creates a louder sound, while a lower amplitude creates a softer sound.

Similar threads

A Question about Sound Waves Propagating Through a Large Metal Cube
    • Mechanics
Replies
10
Views
2K
The physics behind human whistling-where does the sound come from?
    • Mechanics
Replies
4
Views
32K
Sound Wave Problem -- time of flight in air versus in water
    • Introductory Physics Homework Help
Replies
13
Views
2K
Are 7.1 surround sound headphones possible?
    • Mechanics
Replies
6
Views
3K
How Do Soundboards Amplify Sound Energy?
    • Mechanics
Replies
4
Views
11K
Frequency of sound waves from vibrating wire
    • Introductory Physics Homework Help
Replies
6
Views
1K
Sound and air movement: do they affect each other?
    • Mechanics
Replies
4
Views
3K
A question about the speed of EM and mechanical waves
    • Mechanics
Replies
4
Views
3K
Can Silent Sound Waves Be Recorded and Played Back?
    • Mechanics
Replies
2
Views
1K
The Quietest Sound Possible & The Quietest Sound Ever Recorded/Measured
    • Mechanics
Replies
22
Views
20K

Hot Threads

Recent Insights

Back
Top