The nature of sound

Nature of Sound

1. Introduction to Sound Sound is a form of energy that is produced when air molecules vibrate and move in pattern known as waves or sound waves.

2. Sound Wave It i s a l o n git u dina l w a v e. It i s a mechan i c al w a v e . It t r a v els th r oug h ai r , so l i d , and l i qu i d . It doe s no t t r a v el i n a v a c uu m .

3. No t e: When sou n d is t r ans m i t t ed th r ough elect r on ic g ad g e t s , soun d is t r ansl a t ed i n t o t r an s v e r s e w a v e .

4. Characteristics of Sound Look at the wave slope of musical note and noise note below. How do they differ?

5. M usi c al Sound G r aph i c al r ep r ese nt a ti o n s o f n o i s e and mus i c. No i s e ha s n o clear r epe at ab l e p a t t er n . Mus i c ha s a f r equ e nc y ( r epe a t able w a v e), w a v ele n g th , and spee d .

6. Characteristics of Sound Pitch – dependent upon the frequency of the waves Intensity – depends on the amplitude of the waves Quality – depends on the form of the waves

7. Characteristics of Sound 1. Pitch refers to our subjective impression about the “highness or lowness” of a tone , which is related to the frequency of the tone.

8. F r eque n cy – de s cri b es h o w of t en soun d w a v es vi b r a t e pe r un it o f time. 1 hert z = 1 v ib r a ti o n / se c ond H i gh f r equ e nc y v s Low F r equ e ncy

9. Characteristics of Sound L ow-frequency produces a sound with low pitch. High frequency produces a sound with high pitch

10. L o w F r eque n cy sou n d s c an t r a v el a r ound ob s t acles , and c an t r a v el l on g d i s t anc e s . 2 00 Hz and under . High F r eque n cy sou n d s which the frequency 200 Hz and higher. E x amp l es L o w F r eque n cy Hu m o f L i on rum b l e of a big truc k. H i gh F r eque n cy ch i r p i n g o f b i r ds w h istle or siren

11. E x amp l es L o w F r eque n cy Hu m o f wha l es L i on , elepha n ts H i gh F r eque n cy ch i r p i n g o f b i r ds Here are a few examples of low-frequency sounds : Severe weather  Waves Avalanches Earthquakes Whales  Elephants Hippopotamuses  Giraffes

12. E x amp l es L o w F r eque n cy Hu m o f wha l es L i on , elepha n ts A high-frequency sound Whistles Mosquito Computer devices Screaming Squeaking mice Glass breaking Nails on a chalkboard

13. 2. Intensity refers to the amount of sound energy of a wave that is transported past a given area of the medium per unit of time. - unit: watts/meter ² * Loudness is the sensation on the ear that the intensity of sound wave produces. -Unit : dB Characteristics of Sound

14. * Decibel scale is used to measure sound intensity . (dB) * Threshold of hearing - the minimum intensity of sound for a person with normal hearing is at 10-12 w/m². Characteristics of Sound

15. Decibel System(dB) was named after Alexander Graham Bell , the one who invented the telephone. Decibel Meter is a device that is designed to accurately measure the sound or noise that can be heard by the human ear .

16. I n t en s i t y – mea s u r es the ene r gy o f sou n d . The h igher the ene r g y , t h e h igher the i n t ens i t y . dB 10 dB 20 dB 65 dB 85 dB Sound sof t wh isper ru s t l i n g o f l e a v es hu m an c o n v e r s a t i on v acuum cleaner 1 dB 110 dB 150 dB R oc k Mu s ic J e t E ng i ne J e t E ng i n e a t t a k e- o f f

17. 3. Quality or Tone *Tone refers to the sound quality. It depends on the combination of different frequencies of sound waves. Characteristics of Sound

18. Thank You for Listening!