1. Audible frequencies
1.1. Sounds above upper hearing limit
1.1.1. ultrasound
1.2. Sounds lower hearing limit
1.2.1. infrasound
1.3. Frequency range refered to as range of audible frequencies
1.4. Human hear sounds between 20hz and 20kHz
2. Speed of sound in air
2.1. Distance/Time taken
2.2. Echo
2.2.1. Distance to wall and back/Echo timee
2.2.2. Sound waves can be reflected by large,hard surfaces. Reflected sound is heard as separate sound after interval of silence.
3. Pitch and Loudness of Sound
3.1. Pitch
3.1.1. property which distinguishes sounds
3.1.2. Vary from sharp squeal of tyres braking to low thud of bass drum
3.1.3. higher frequency of sound, higher pitch
3.1.4. eg. piano,violins and guitars have strings which vibrate to produce musical notes. Longer the string, lower the pitch
3.2. Amplitude
3.2.1. Greater amplitude, louder sound
3.2.2. eg. when pianist gently depresses piano key, little hammer in piano taps the piano string softly,making it vibrate with small amplitude
4. Ultrasound
4.1. type of sound wave with frequencies greater than 20kHz
4.2. Many medical and commercial uses
4.2.1. Examples
4.2.1.1. Ultrasonic scanning in medicine involves sending ultrasound waves into patient's body and detecting the reflected ultrasound
4.2.1.1.1. used to examine internal tissues and organ of patient
4.2.1.1.2. check development of foetuses
4.2.1.1.3. detect abnormal growths
4.2.1.2. Sonar
4.2.1.2.1. technique of using ultrasound to locate underwater objects, applies the principle of echo-sounding.
4.2.1.3. High frequency of vivrations caused by ultrasound used in cleaning of small,intricate items jewellery,spectacles and small machine parts
4.2.1.3.1. as ultrasonic vibrations travel through liquid, dirt and corrosion would be loosened out
4.2.1.4. used in quality control and continuous monitoring during manufacturing processes
4.3. cannot be heard by humans, but can be heard by other animals like bats and dogs
5. Definition
5.1. propagated in the form of longitudinal waves form one point to another as a wave
6. Waves
6.1. produced when vibrating object alternately pushes and pulls on the air adjacent to it, causing small but rapid changes in the air pressure
6.2. eg. tuning fork is sturuck, diaphragm of loudspeaker vibrates
6.3. Need medium for transmission
6.3.1. travels fastest in solid followed by liquid and gas
6.3.1.1. due to differences in strenth of inter atomic forces and closeness of atoms in three states