What is Sound?

Sound is a type of energy made by vibrations. When any object vibrates, it causes movement in the air particles. These particles jump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. This movement, called sound waves. Picture a store thrown into a still body of water. The rigs of waves expand indefinitely. When the vibrations are fast, you hear a high note. When the vibrations are slow, it creates a low note.

 

How do Wind Instruments make Sound?

In wind instruments, like the flute and trumpet, vibrating air makes the sound. The air particles move back and forth crating sound waves. Blowing across a flute’s blow hole sets up Slinky like waves in the tube. In the clarinet, a vibrating reed gets the waves started.

How do String Instruments make sound?

Stringed instruments are played by pressing the fingers down on the strings. This pressure changes the strings’ length, causing them to vibrate at different frequencies and making different sounds. Shortening a string makes it sound higher.

What is the frequency of sound waves?

When we draw a sound wave, the wave peaks and valleys are close together or far apart. Sound waves vibrate at different rates or “frequencies” as they move through the air. German physicist who experimented with sound in the 19th century. Amplitude is the objective measurement of the degree of change in atmospheric pressure caused by sound waves. Sounds with greater amplitude will produce grater changes in atmospheric pressure from high pressure to low pressure. Amplitude is almost always a comparative measurement, since at the lowest-amplitude end, some air molecules are always in motion and at the highest end, the amount of compression and rarefaction though finite, is extreme.

Pitch and Frequency

A sound wave, like any other wave, is introduced into a medium by a vibrating object. The vibrating object is the source of the disturbance could be the vocal cords of a person. Sound is transmitted by particles in a solid, liquid or gas colliding with each other. It is a wave which is created by vibrating objects and propagated through a medium from one location to another.

 

The speed of sound in an ideal gas is independent of frequency, but it weakly depends on frequency for all real physical situations. It is a function of the square root of the absolute temperature, but is nearly independent of pressure of density for a given gas

ss ure. Amplitude is almost always a comparative

The speed of sound is inversely dependent on square root, since sound in gases is a type of compression. However, the speed of sound varies from substance to substance. Sound travels faster in liquids. 

Audible and inaudible sounds

Audible and inaudible sounds are relative terms. Audibility of sound depends upon capability of ear. Hence the sounds having frequencies above and below this range are inaudible sounds for the human beings. Ultra sonic sound is audible for such creatures and the same kind of sound is inaudible to the human beings.

A percussion instrument is a musical instrument that is sounded by being struck or scraped by a beater. The percussion family is believed to include the oldest musical instruments.

 

S o u n d i s t r a n s m i tt e d b y p a r ti c l e s ( a t o m s o r m o l e c u l e s ) i n a s o l i d , l i q u i d o r g a s c o l l i d i n g

Air particles moves in a to and fro position where they collide with each other to form a cluster then they rebound from each other. The air particles do not move over a large area but, carry the sound by air particles.

 Sound Needs a Medium to Travel

The origin of sound is always some vibrating body. In some cases the vibrations of the source may be very small or very large that it may not be possible to detect them. Human voice originates from the vibrations of the vocal chords. Sound travels in the form of longitudinal wave and it requires a material medium for its propagation. This structure helps you determine the direction of a sound. If a sound is coming from behind you or above you, it will bounce off the piano in a different way than if it is coming from in from of you or below you. Your brain determines the horizontal position of a sound by comparing the information coming from your two ears. If the sound is to your left, it will arrive at your left ear a little bit sooner than it arrives at your right ear.

Sound Needs a Medium to Travel

The origin of sound is always some vibrating body. In some cases the vibrations of the source may be very small or very large that it may not be possible to detect them. This type of vibrations is produced by tuning fork, drum, bell, the string of a guitar etc. Human voice originates from the vibrations of the vocal chords and the sound from the musical instruments is due to the vibrations of the air columns. Sound travels in the form of longitudinal wave and it requires a material medium for its propagation.

Catching Sound Waves

The pinna, the outer part of the ear, serves to "catch" the sound waves. Your outer ear is pointed forward and it has a number of curves. This structure helps you determine the direction of a sound. If a sound is coming from behind you or above you, it will bounce off the pinna in a different way than if it is coming from in front of you or below you. This sound reflection alters the pattern of the sound wave. Your brain recognizes distinctive patterns and determines whether the sound is in front of you, behind you, above you or below you.

Ear diagram courtesy NASA

Percussion instrument

The percussion section of an orchestra, however, traditionally contains in addition many instruments that are not, strictly speaking, percussion, such as whistles and sirens. On the other hand, keyboard instruments such as the celesta are not normally part of the percussion section, but keyboard percussion instruments (which do not have keyboards) are included.

Air particles moves in a to and fro position where they collide with each other to form a cluster (compression) then they rebound from each other, the same effect of hitting a ball against a wall (rarefaction) - i.e. a series of mechanical compressions and rarefactions. Sounds are carried this way by the air particle in a outward fashion similar to ripple in a pond as it continues to collide with air particles.