1. Sound

2. Waves transfer energy without transferring matter.
What is a wave?
A wave is a repeating disturbance that transfers energy through matter or space.
When an object vibrates it causes the particles around it to move.
These particles bump into particles close to them, transferring energy possessed. This continues until they run out of energy.
Longitudinal Waves
Waves transfer energy without transferring matter.
Transverse Waves

3. Therefore sound can be defined as …
A form of energy caused by vibrations. This energy is transferred due to pressure through longitudinal waves.
In a longitudinal wave the matter in the wave moves back and forth parallel to the direction of the wave.
Sound doesn’t travel through vacuum.

4. Sound can be reflected, refracted, and absorbed and also shows evidence of interference and diffraction.
Reflection of sound is also be known as echo.
Reverberation of sound is the repeated multiple reflection of sound in any enclosed space.
Reverberation occurs when the echo produced is as same/strong as the sound produced by the source.
Refraction of sound occurs when the wave travels from one medium to another.

5. Frequency (f) is waves per second.
Wavelength
Wave Speed  f
Time period
Wavelength () is the distance from the center of one compression to the center of the next compression.
Time period (t) is the time it takes for one full wavelength to pass a certain point.
Frequency (f) is waves per second.
Wave Speed (s) the distance covered by a complete wave in a given time.

6. Compressions
The close together part of the wave.
Rarefactions
The spread-out parts of a wave.
Amplitude is the maximum distance the particles in a wave vibrate from their mean positions. Amplitude controls the volume and intensity of sound.
The amplitude of a longitudinal wave is determined by the closeness of the longitudinal waves. The closer the longitudinal waves and the farther the rarefaction lines.
Spring A has greater amplitude than Spring B.

7. Speed of Sound 344 m/s in air at 20°C Speed of Sound depends on:
Type of medium
travels better through liquids and solids
can’t travel through a vacuum
Temperature of medium
travels faster at higher temperatures.

8. Doppler Effect Doppler Effect
change in wave frequency caused by a moving wave source.
moving toward you - pitch sounds higher.
moving away from you - pitch sounds lower.

9. Interference
Waves interfere in one of two ways: Constructive Interference and Destructive Interference.

10. The frequency of sound Frequency of a sound wave is heard as pitch.
highness or lowness of a sound
Low frequency= Low pitch = Long wavelength.
High frequency = High pitch =
Short wavelength.
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11. Healthy humans can hear from 20 Hz to 20,000 Hz
High Pitch. Eg. Piccolo
Low pitch. Eg. Fox horn
Healthy humans can hear from 20 Hz to 20,000 Hz
Ultrasound
- sound waves with frequencies above the normal human range of hearing.
Ultrasonic sounds have frequencies greater than Hz.
Infrasound
- sounds with frequencies below the
normal human range of hearing.
Infrasonic sounds have frequencies lower than 20Hz.

12. Some animals can hear sounds with frequencies greater than 20000 Hz.
a) Dogs (up to 35,000 Hz)
Bats (over 100,000 Hz
Medical diagnosis.
Medical Imaging
Uses of sound
a. Acoustics – the study of sound.
b. SONAR – Sound Navigation and ranging (echolocation).
c. Ultrasound imaging.

13. Different sounds that you hear include
(A) noise
(B) pure tones
(C) musical notes or beats.
A - can be considered as noise as it has no pattern.
B – can be considered as a pure tone as energy is transferred in a single pattern of the wave.
C - musical notes or beats as it has a pattern of deliberate pitches and amplitudes.

14. Beats are variations of loudness (amplitude) and pitch (frequencies) caused by interference of two sounds that slightly differ.
Beats differ depending on the pattern of amplitude, pitch and caused by interference of different waves.

15. How do musical instruments create sound?
Clarinet
How do musical instruments create sound?
Flute
It depends on the type of instrument. There are four types. Woodwind. String.
Percussion. Brass.
Oboe
Woodwinds
Instruments
Piccolo
Bassoon
Woodwinds make music by blowing on the top of the instrument or on a reed.

16. String Instruments
Some of the simpler instruments are the string instruments. String instruments make sound with vibrating strings, and the pitch is modified by the thickness, tension, and length of the string.
Harp
Guitar
Violin
Electric Guitar
Cello

17. Percussion Instruments
Drum
Percussion Instruments
Piano
Percussion instruments make music by striking, shaking or scraping them.
Tambourine
Cymbals
Maracas
Xylophone

18. Brass instruments make music by buzzing lips while blowing.
Trombone
Tuba
Trumpet
French Horn

19. Thank you …. Prasad Kulkarni M.Sc. B.Ed.