The document discusses key topics relating to sound, including that sound is pressure waves that propagate as longitudinal waves, with the speed of sound increasing with higher temperatures. It also describes how the human ear detects sound vibrations and transmits them to the brain as electrical signals to perceive characteristics like pitch, timbre and loudness. Methods for measuring sound in decibels based on pressure, power and intensity are also presented.

1. Sound
By Prof. Hitesh Dholakiya
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a
Engineering Funda Android App Audio Video YT Playlist

2. Outlines
 Basics of Sound
 Propagation of Sound
 Velocity of Sound
 Measurement of Sound
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a
Engineering Funda Android App Audio Video YT Playlist

3. Basics of sound
 Sound is pressure waves.
 As it travels based on pressure difference.
 Sound is longitudinal waves.
 Amplitude of oscillation is there in the direction of propagation
 For Humans, sound waves are there in range of 20Hz to 20000Hz.
 In general, Females has higher frequency of tones as compared to
males.
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a
Engineering Funda Android App Audio Video YT Playlist

4. Basics of sound
 Sound is the sensation we perceive when vibrations in the air are
detected by our ears.
 Our ears converts this vibrations into electrical impulses.
 These impulses are transmitted to our brain via our nervous system.
 Our brain then distinguishes its three main characteristics.
 Pitch
 Timbre
 Loudness
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a

5. Propagation of sound
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a

6. Velocity of sound
 Sound velocity is directly proportional to root of Temperature.
𝑣 ∝ 𝑇
 Here, Temperature T should be considered in kelvin.
 At 200
C, velocity is 344 m/sec.
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a

7. Measurement of sound
 Sound can be measure in terms of dB with pressure as per
 Sound can be measure in terms of dB with Power as per
 Sound can be measure in terms of dB with Intensity as per
𝐿𝑃 = 20 log
𝑃
𝑃0
𝐿𝑊 = 10 log
𝑊
𝑊0
𝐿𝐼 = 10 log
𝐼
𝐼0
Where, P = Pressure and 𝑃0 = 2 × 10−5
𝑃𝑎
Where, W = Power and 𝑊0 = 10−12
𝑊
Where, I = Intensity and 𝐼0 = 10−12
𝑊/𝑚2
E
n
g
i
n
e
e
r
i
n
g
F
u
n
d
a