Sound properties

1. Sound
• How are sounds Classified?
• How are sounds produced?
• How are sounds different?
• How are sounds measured?
• How fast does sound move?

2. Sound Waves
• Each Sound wave
has unique pattern
• Frequency
• Wavelength
• Amplitude

3. Sound mediums
• A medium is a material that sound, a form of energy,
need to transfer
• Speed of sound
– Solid : Fast speed
– Liquid : Medium speed
– Gas : Slow Speed
• Standard Temperature and Pressure = 3.31 x 102 m/s
– Vacuum : No Sound

4. Frequency of Sound
• Pitch of the sound
• Musical notes: there are 12 notes on a staff from
A to G#
• Bass : Low frequency 0 to 300 Hz
• Mid range : “voice” 300 to 6,000 Hz
• Treble : High frequency, Above “middle” C
note, 6,000 to 20,000 Hz
• Spectrum of frequency

5. Amplitude of Sound
• Volume control
• Loudness
• Strength of the wave ( measured in db “decibels”)
• Energy of the wave

6. Reflection and Refractions of
Sound waves
• Echo
– Reflection of sound off a surface (Acoustics (Greek
akouein,”to hear”),. It is more commonly used for
the special branch of that PHYSICS that deals with
the construction of enclosed areas so as to enhance
the hearing of speech or music.
• Reverb (Electronic echo)
• Resonance
– electronic envelope Helmholtz Resonator, spherical
vessel of metal or glass with an opening and an
earpiece on opposite sides.
– The ear canal acts enhancing frequencies in the
range from 1000 to 4000 Hz (hertz, or cycles per
second).

7. Speed of Sound
• Velocity(v) of a wave= Frequency (f) times the
wavelength (l)
• V = f l
• The speed of propagation of sound in dry
air at a temperature of 0° C (32° F) is
331.6 m/sec (1088 ft/sec). If the
temperature is increased, the speed of
sound increases; thus, at 20° C (68° F),
the velocity of sound is 344 m/sec (1129
ft/sec)

8. Resonance of Sound
• Any oscillating object has a natural
frequency, which is the frequency
an oscillating object tends to settle
into if it is not disturbed.
•The phenomenon in which a
relatively small, repeatedly applied
force causes the amplitude of an
oscillating system to become very
large is called resonance

9. Interference of Sound
• Constructive interference
–The displacement of the disturbance of 2
waves are the same (Similar sounds
•Frequency are the same or multiple.
•Destructive interference
–The displacement of the disturbance of 2
waves are the different (Unlike sounds)
•Frequency are the different or not a
direct multiple.

10. Beats
• The pulse, or pattern of regular
accents, of a musical piece can
be broken into individual pulses,
or beats
• a fractional symbol in which the
numerator specifies the number of
beats per bar, and the
denominator specifies the relative
note value assigned to one beat

11. Doppler Effect
• The frequency of the perceived wave is
changed by the motion of the source
–Increasing Frequency when the
source approaches the sensor
–Decreasing Frequency when the
source increases the distance from
the sensor

12. Summary
• Sounds are created by Moving molecule in the
medium ( Solid, Liquid and Gases)
• Sounds are measured by Frequency, Wavelength,
Speed, and Amplitude.
• Sounds can combine by interference
• Sounds can be changed by the Acoustics of the
Area or the speed of the source
(Doppler Effect)
• Sounds are used in many devices.