Sound is a form of energy which trans-locates through matter.
This matter includes air, water and solid matter.
Without matter there is no sound propagation. This sound has energy and is directly dependent on it.
To produce a sound one needs energy and but is not a viable form like photons of light.
This sound propagates in the form of waves through air.
These waves have frequency and wavelength as measurable parameters.
The sound quality largely varies due to these two parameters.
For humans and animals this sound is useful in one or other way and has great importance.
Importance of sound human life
1. For communication: Sound is the only main form of communication for animals while it is the key for humans communicate with spoken languages besides body languages.
Animals communicate in their own language of sounds by moan, cry, weep etc.
For humans, this voice communication expands to telephonic (distant communication) means by using mobiles and phones.
The communication is understood by ears through hearing, auditory words, expressive tone etc. One can express feeling just by sound variation even.
2. Signalling system: Sound is the signalling system used for trains, automobiles, river flows (Dam water release), industry sirens.
Sound as a signalling system is used as horns, sirens, calling bells, beeps etc. Sound signal system is one of the least expensive ones. Further it is less harmful to the environment around. But excess and frequent use can cause sound pollution.
Further alarm system uses sound. Hence a mobile ringing, alarms, message alerts use sound as alerting means.
3. Echo system: Echo is a reflection of sound arriving back to the point of emission. We can notice echo when we make a notice in an empty building or well or even boot sounds of army march. Echo is a type of sound resonance. It is very much useful in music.
4. For music: Music is the art which relies solely on sound. Without sound there is no music from music systems. Music communicates message, soothes the mind and also helps relieve stress.
Music is a sound in a controlled and fine tuned manner. Music relies a lot on frequency and pitch of the voice.
For instruments the factors like the frequency, intensity and also the resonance of the sound matter. Hence you can notice for instruments like violin, guitar there is a big hallow at the end. This hallow creates resonance of sound making the music further distinct to the instrument.
This is music is now a day recorded for future use by sound reproduction systems.
5. For finding the depth/ distant objects: This you might have come across in physics. Sound waves are one of the few means available to measure the depth of the seas and also the deep holes in the earth. Also other objects at a long distance can be found by SONAR waves i.e SOUND NAVIGATION AND RANGING. The sound is allowed to travel through the sea or ocean bed and return back. This time taken by particular frequency of sound to reach the sea bed and return back to the source or absorber (receiver of sound) is used to calculate the depth of the sea.
Similarly a moving object can send sound waves in the direction of its motion and know if any there are any objects moving in at long distances.
6. For degassing of liquids: Liquids like water and solvents used in analysis have air and other gases entrapped inside them. This air has to be removed for proper flow through minute pores in the matter. This is particularly required for chromatography experiments. The procedure to remove gas from the solvent is called degassing of solvents. This is essential for proper analysis of compounds using HPLC (high performance liquid chromatography) or else it can slow down the pressure in the column and hinder analysis.
7. For de-granulation of solid particles: Large solid particle in a suspension or tissues fraction can be broken down by grinding. But very small particles like less than 1mm or so cannot be broken down further using grinders. Then they can be broken down by use of ultrasonic sound waves. These waves are thought to create vigorous crests and troughs in the liquid media. These crests and troughs bring about splitting of particles to smaller ones.
8. Telephone communication: Telephone is one of the best discoveries ever made by man. The telephone machine receives sound waves from the person at mouth piece. The sound waves cause vibration in carbon particles in it. Thus the electric signal is generated based on the pitch and frequency of voice and is communicated. Here the sound from the voice exerts pressure on the diaphragm in the mouth piece.
This is the procedure followed to break suspension to nano particle size for better use. The apparatus used for this purpose is called sonicator.
9. In sterilization: Ultra sound is also tried in sterilization. This is done to inhibit growth of microbes and even kill them.
Sonication disrupts the cell wall of bacteria and kill them. But they are not highly lethal but are used in combination with disinfectants for synergistic effect.
10. To enhance cell growth: Sonication is also found to be effective in tissue culture. Some findings suggest that use of sonication selectively enhances the growth of cells & tissues. Also it is found to facilitate gene transfer during tissue culture & in biotechnology. refer.