1. Elements of Acoustic Phonetics
Chapter 1: Sound Waves

2. What is sound?

3. What is sound?
Vibrations

4. Vibrations So what are vibrations? Movement of particles.
What is sound?
Vibrations
So what are vibrations?
Movement of particles.

5. What is sound?

6. What is sound?

7. What is sound?

8. How fast does sound travel?
In the air about 780 mph.
In more dense materials it travels faster.
Example: Someone taps on rail and yells at the same time.
Speed of Sound
Lightning and Thunder

9. How fast does sound travel?
Does temperature affect speed of sound?
Speed of Sound and Temperature
Why does this happen?

10. Frequency Amplitude Quality
3 Ways a Sound Differs
Frequency
Amplitude
Quality

11. How often the wave (air pressure variations) repeats
Frequency
How often the wave (air pressure variations) repeats

12. Frequency Frequency is measured in Hertz (cycles per second)‏
Pitch is the audible impression of frequency.

13. Frequency
If we double the freq. people perceive the pitch to be twice as high, but tripling it doesn't make it 3 times as high.
The note A four octaves higher has a frequency 8 times greater not 4.

14. Frequency Human hearing is logarithmic.
Small changes at lower frequencies are perceptible.
The same small changes are not perceptible at higher frequencies.
Larger changes are required at higher frequencies to be perceptible.

15. Frequency Humans can hear about 20-20,000 Hz
Speech occurs between 20 and 8,000 Hz
Dogs hear 40-60,000 Hz
Mice hear 1,000-80,000 Hz

16. Frequency How do you change the frequency that something vibrates?
Factors that affect frequency

17. What if you really make the strings long? The Long Stringed Instrument
Frequency
What if you really make the strings long?
The Long Stringed Instrument

18. How do we hear sounds?

19. Amplitude
How much air is displaced or how large the differences in pressure are.

20. Amplitude Amplitude is measured in decibels.
Volume is the audible impression of amplitude.
Doubling amplitude makes people feel the volume has doubled, but tripling it does not sound three times louder.

21. Amplitude Human hearing is logarithmic.
Small changes at lower amplitudes are perceptible.
The same small changes are not perceptible at higher amplitudes.
Larger changes are required at higher amplitudes to be perceptible.

22. Relationship between frequency and amplitude
What happens if there are more molecules in the compression, and fewer in the rarefaction areas?

23. Relationship between frequency and amplitude
What happens if there space between the areas of condensation is larger, but the number of molecules stays the same?

24. Relationship between frequency and amplitude
Imagine dropping the bob of a pendulum from a low point and from a high point. Which will result in more swings per second?

25. Relationship between frequency and amplitude
Imagine dropping the bob of a pendulum from a low point and from a high point. Which will result in more swings per second?
How would you change the frequency?

26. Review videos

27. What varies in this wave?

28. What varies in this wave?

29. What varies in this wave?
AM=amplitude modulated
FM=Frequency modulated

30. What varies in this wave?

31. What varies in this wave?
Quality/Timbre

32. Amplitude, Frequency, Wavelength Timbre (Quality)

33. What is the amplitude and frequency of a voiceless stop?
Waveforms
What is the amplitude and frequency of a voiceless stop?

34. What is the amplitude and frequency of a voiceless aspirated stop?
Waveforms
What is the amplitude and frequency of a voiceless aspirated stop?

35. What is the amplitude and frequency of a voiced stop?
Waveforms
What is the amplitude and frequency of a voiced stop?

36. What is the amplitude and frequency of a voiceless fricative?
Waveforms
What is the amplitude and frequency of a voiceless fricative?

37. What is the amplitude and frequency of a voiced fricative?
Waveforms
What is the amplitude and frequency of a voiced fricative?

38. What is the amplitude and frequency of an affricate?
Waveforms
What is the amplitude and frequency of an affricate?

39. What is the amplitude and frequency of a nasal?
Waveforms
What is the amplitude and frequency of a nasal?

40. What is the amplitude and frequency of liquids?
Waveforms
What is the amplitude and frequency of liquids?

41. What is the amplitude and frequency of a vowel?
Waveforms
What is the amplitude and frequency of a vowel?

42. Waveforms
What is this word?

43. Waveforms
What is this word?

44. Waveforms
What is this word?

45. Waveforms
What is this word?