1. 1 13.3 Musical notes and noise Male and female singers Introduction Musical notes Check-point 3 Noise Check-point 4 ?

2. 2 13.3 Musical notes and noise Male and female singers Leo and Joey are popular singers in Hong Kong. Do you love to hear their songs?

3. 3 13.3 Musical notes and noise Male and female singers Discuss: 1Who can sing a higher note? Joey 2If they sing the same note, you can distinguish who sings the note. What is the difference between the notes they sing? The pitch of the note sung by Joey is higher than that by Leo.

4. 4 13.3 Musical notes and noise Introduction A note is a sound produced by the regular vibrations. A noise, which is not pleasant to hear, is caused by irregular vibrations.

5. 5 13.3 Musical notes and noise Experiment 13c Musical notes Start the frequency from 20 Hz and gradually increase it. Hear how the pitch of the note changes. Watch the change of the waveform on CRO.

6. 6 13.3 Musical notes and noise Experiment 13c Musical notes Set the frequency to 300 Hz. 1Connect a microphone to the CRO. 2Strike a tuning fork and bring it near the microphone. 3Watch the waveform on the CRO. 4Repeat by singing ‘doh’, ‘re’, ‘me’, etc. into the phone.

7. 7 13.3 Musical notes and noise Experiment 13c Musical notes Video

8. 8 13.3 Musical notes and noise 1Musical notes When we compare notes, we compare their... - pitch - quality - loudness

9. 9 13.3 Musical notes and noise 1Musical notes aPitch The pitch of a note depends on the frequency of the sound. On  frequency in Expt. 13c, the pitch of the note  … … the number of waves 

10. 10 13.3 Musical notes and noise bLoudness Demonstrated by CRO and signal generator... Loudness of a note depends on the amplitude of the sound wave. loudness (amplitude) pitch (freq.)

11. 11 13.3 Musical notes and noise 1Musical notes

12. 12 13.3 Musical notes and noise cQuality Note = fundamental freq. f + overtones (overtones = notes of freq. of multiples of f ) Quality of a note depends on number and amplitude of overtones accompanying the fundamental freq. Tuning fork Er-hu Chinese flute French horn

13. 13 13.3 Musical notes and noise Video Simulation cQuality

14. 14 13.3 Musical notes and noise Experiment 13d 1Connect the microphone to the computer. Run the recording software. 2Speak the vowels ‘a’, ‘e’, ‘i’, ‘o’ and ‘u’ into the microphone. 3Find the fundamental frequency and the overtones. Analysing sounds

15. 15 13.3 Musical notes and noise Experiment 13d Analysing sounds Video

16. 16 13.3 Musical notes and noise Check-point 3 1Which of the following…Which of the following… 2Match the terms…Match the terms… 3Sound is produced by…Sound is produced by…

17. 17 13.3 Musical notes and noise Check-point 3 - Q1 Which of the following quantities of the two waveforms are the same? AFrequency BAmplitude CQuality

18. 18 13.3 Musical notes and noise Check-point 3 - Q2 Match the terms of the left column and the phases of the right column. Quality Loudness Pitch Amplitude of sound Combination of different numbers and amplitudes of overtones added to the fundamental note. Frequency of sound

19. 19 13.3 Musical notes and noise Check-point 3 - Q3 Sound is produced by __________of air particles. The higher the frequency of sound waves, the higher the __________ of sound; the greater the amplitude of sound waves, the greater the __________ of sound. vibrations pitch loudness

20. 20 13.3 Musical notes and noise 2Noise Stand near a construction site, a busy road, or underneath an aircraft flying overhead. Noises can be... irritating, unbearable, affects our work and health. It is a serious problem in a big city like Hong Kong!

21. 21 13.3 Musical notes and noise 2Noise aThe decibel scale jet aircraft at 30 m to measure sound intensity level

22. 22 13.3 Musical notes and noise aThe decibel scale disco, 1 m from loudspeaker

23. 23 13.3 Musical notes and noise aThe decibel scale road drilling at 5 m

24. 24 13.3 Musical notes and noise aThe decibel scale noisy factory, passing train, heavy road traffic

25. 25 13.3 Musical notes and noise aThe decibel scale average factory noisy restaurant

26. 26 13.3 Musical notes and noise aThe decibel scale vacuum cleaner at 3 m

27. 27 13.3 Musical notes and noise aThe decibel scale normal talking

28. 28 13.3 Musical notes and noise aThe decibel scale quiet talking

29. 29 13.3 Musical notes and noise aThe decibel scale country park

30. 30 13.3 Musical notes and noise aThe decibel scale threshold of hearing

31. 31 13.3 Musical notes and noise aThe decibel scale A sound intensity level meter can be used to measure sound intensity levels. electronic ear

32. 32 13.3 Musical notes and noise bHow noise affects you 140 dB 130 dB causes permanent damage to the ear produce ear pain constant exposure to loud noise loss of hearing !!!

33. 33 13.3 Musical notes and noise bHow noise affects you Work place: sound intensity level > 90 dB without ear protection By law, not allow to work continually for 8 hours

34. 34 13.3 Musical notes and noise cAcoustic protection We should protect our ears from excessive noise. - Do not turn up the volume of the MP3 players too high. The noise level can be very high without we realizing it.

35. 35 13.3 Musical notes and noise cAcoustic protection Large-scale constructions must comply with noise standards by the Environmental Protection Department (EPD).

36. 36 13.3 Musical notes and noise Check-point 4 1Describe briefly the unit…Describe briefly the unit… 2If the sound intensity level…If the sound intensity level…

37. 37 13.3 Musical notes and noise Check-point 4 - Q1 Describe briefly the unit decibels. Decibel is the unit of _________________ and its symbol is ________. The value of the lowest sound value is ____ and it is called ___________________. sound intensity level dB 0 threshold of hearing

38. 38 13.3 Musical notes and noise Check-point 4 - Q2 If the sound intensity level of a noise is __________ dB, people will get permanent ear damage. In Hong Kong, it is illegal to work for __________ hours continually without ear protection in places where the sound intensity level is over __________ dB. 140 8 90

39. 39 13.3 Musical notes and noise The End

40. 40 13.3 Musical notes and noise Microphone picks up the sound of a tuning fork. The waveform is displayed on a suitably adjusted CRO. Sketch the waveforms observed when (a)tuning fork sounds a steady note, Waveforms of different notes Example 5 (b)the tuning fork is struck harder to give a louder note, (c)another tuning fork of higher frequency is sounded.

41. 41 13.3 Musical notes and noise (a)tuning fork sounds a steady note, The tuning fork gives a ‘pure’ note displayed on the CRO as a ‘sine wave’ Waveforms of different notes Example 5

42. 42 13.3 Musical notes and noise (b)the tuning fork is struck harder to give a louder note, louder note larger amplitude Waveforms of different notes Example 5

43. 43 13.3 Musical notes and noise (c)another tuning fork of higher frequency is sounded. higher frequency more waves are shown Waveforms of different notes Example 5

44. 44 13.3 Musical notes and noise Return