How to Troubleshoot Apps for the Modern Connected Worker
Sound
1.
2. Sound
• Sound means basically the mechanical
vibrations.
• These vibrations require a material
medium to travel through.
eg : Solid, liquid, gas, plasma
• Meaning Sound cannot travel through
Vacuum. (Why ?)
3. Sound as Wave
• Sound travels in the form of waves.
• Wave : A wave is a disturbance that
propagates through space and time,
usually with transference of energy.
• Waves travel and transfer energy from
one point to another, often with no
permanent displacement of the particles of
the medium (that is, with little or no
associated mass transport); they consist
oscillations or vibrations (of particles)
around almost fixed locations.
4. Types of waves
• Transverse Wave : Transverse waves are
those with vibrations perpendicular to the
direction of the propagation of the wave;
examples include waves on a string, and
electromagnetic waves.
• eg. : Light (i.e. Electromagnetic waves)
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=35
5. Types of waves
• Longitudinal waves : Longitudinal waves
are those with vibrations parallel to the
direction of the propagation of the wave.
eg : Sound wave, Mechanical waves
http://www.surendranath.org/Applets/Waves/Lwave01/Lwave01Applet.html
9. Wavelength (λ)
•The distance between any two adjacent wave crests1
(wave crests that are next to each other) or any two
adjacent wave troughs2
in a wave.
1. Crest: The highest point reached by a wave.
2. Trough: The lowest point reached by a wave.
10. Amplitude (A)
•The maximum displacement (difference between an
original position and a later position) of the material that
is vibrating. Amplitude can be thought of visually as the
highest and lowest points of a wave.
12. Frequency (f/n)
•The number of wave crests (or wave troughs) that
pass a given point per unit of time (usually per
second).
• Frequency (f) = 1 / Time Period (T)
• SI unit of ‘f’ is Hertz (Hz).
• Hz = 1 / sec
13. Velocity of wave
• The distance travelled divided by the time taken.
• Velocity (v) = Distance (λ) / Time taken (T)
v = λ x f
14. How sound is produced
Sound travels due to vibrations
(disturbance) produced in the medium.
• Video 1
• Video 2
• Video 3
• Video 4
15. How sound travels
Sound travels through material medium in
the form of compression and rarefaction.
• Video 1
• Video 2
• Video 3
16. Speed of sound
• It is the speed with which a sound pulse
travels from the source to the observer.
• Sound travels through air at NRTP with 334
m/s.
Factor affecting speed of sound :
Density of medium : Speed of sound is
directly proportional to the density of the
medium.
17. Speed of sound
1 Mach (M) = 334 m/sec
• Subsonic: M < 1
• Sonic: M = 1
• Supersonic: 1 < M < 5
• Hypersonic: M > 5
18. Reflection of sound
• We know, <i = <r (Refer practical sheet)
• Some examples : Stethoscope,
Soundboard
• Lets see some more examples :
• Video 1
• Video 2
• Video 3
19. Echo
• Reflection of sound is called Echo.
• We can hear two consecutive sounds only
if there is a time gap of 1/10th
of a second
(0.1s).
• Note that this value is only for sound in air
and will be different for different mediums.
• Let us calculate the minimum distance to
hear a Echo…..
20. Reverberation
• Basically it is unwanted Echo.
• Reverberation in a hall can be avoided by
use of :
i. Panels made of porous & soft materials.
ii.Using floor carpets
iii.Using curtains, sofa sets etc.
21. Human Ear
• Human ear senses sound by the vibration of ear drums.
eg: Video 1 , Video 2, Video 3
• The human can hear all the frequencies between
20 – 20,000 Hz.
• Frequencies < 20 Hz are called Infrasonic.
eg : Whales
• Frequencies > 20,000 Hz are called Ultrasonic.
eg : Bats
22. Ultrasound
•As ultrasound have high frequency they have high
energy & high penetration power which makes it
helpful in many tasks.
Eg : i . To study internal organs in body.
ii. To study the development of fetus.
iii. To break kidney stones.
iv. Used in SONAR.
SONAR (SOund Navigation And Ranging) is a
technique that uses Ultrasonic frequency to
navigate, communicate with or detect other
vessels & to study the landscape.