1 / 49

The Philosophy and Physics of Sound: Exploring the Nature of Sound Waves

Dive into the philosophical and physical aspects of sound waves. Explore the causes and effects of sound, measurement of pressure, air movement, the forces involved in sound, components of sound waves, and more.

mbriley
Download Presentation

The Philosophy and Physics of Sound: Exploring the Nature of Sound Waves

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Perry C. Hanavan, Au.D. Audiologist Civic Choir Parody

  2. If a tree falls in the forest, and no one hears it, will there be a sound?...

  3. If a tree falls in the forest, and no one hears it, will there be a sound?... This is an old philosophical dilemma which relies on using the word "sound" for two different purposes. One use is as a description of a particular type of physical disturbance: "Sound is an organized movement of molecules caused by a vibrating body in some medium - water, gas, solid or whatever." The other is as a description of a sensation: "Sound is the auditory sensation produced through the ear by the alteration ... in pressure, particle displacement, or particle velocity which is propagated in an elastic medium." Both definitions are correct, they differ only in the first being a cause and the second being an effect.

  4. Sound saturates the environment

  5. Nasty Noises • Nasty noises: Why do we recoil at unpleasant sounds? • MOST UNPLEASANT SOUNDSRating 74 sounds, people found the most unpleasant noises to be:1. Knife on a bottle2. Fork on a glass3. Chalk on a blackboard  4. Ruler on a bottle5. Nails on a blackboard6. Female scream7. Anglegrinder8. Brakes on a cycle squealing9. Baby crying10. Electric drill • LEAST UNPLEASANT SOUNDS1. Applause2. Baby laughing3. Thunder4. Water flowing

  6. Sound • vibration (movement) • variation in sound pressure • transmission through a medium (gas, liquid, solid) • perceived by listener

  7. How Do We Measure Pressure

  8. Measurement: Pressure • Dynes dyne/cm2 • Pounds per square inch psi • microbar bar • Pascal Pa • centimeters of water cm H2O • millimeters of mercury mm Hg

  9. Old vs. New Units of Measure Old New ------------------------------------------- dynes/cm2 Pascal psi microbar

  10. Metric System • MKS • cgs • http://www.unc.edu/~rowlett/units/cgsmks.html • http://www.bipm.org/en/home/ • Metric System Rap

  11. Pressure at different locations may vary • P atmos • P pos • P neg • P oral • P trach • P alveolar

  12. Air (gas) • consists of molecules • Brownian motion • governed by predictable laws • equal dispersion throughout area

  13. Air Movement • driving pressure: (difference in pressure) high pressure FLOWS to low pressure and low pressure FLOWS to high pressure areas • volume velocity: rate of flow • laminar flow: flow in a parallel manner • turbulent flow: non-parallel manner (flows around an object)

  14. Question Boyle’s Law deals with? • Gravity • Force • Pressure changes with volume • Temperature • I don’t know

  15. Air Pressure, Volume, Density • Volume: amount of space in three dimensions • Density: amount of mass per unit of volume • Boyle’s laws: as volume decreases, pressure increases

  16. Question A condensation is? • Positive air pressure area • Negative air pressure area • Less molecules than other areas • “Rain Drops Keep Falling on My Head” • Speaking down to people

  17. Air Pressure Changes from Sound • Condensation • Rarefaction Soundry Sound wave applet Amplitude Peak amplitude Wavelength Period

  18. Propagation of Sound • Condensations • Rarefactions • Example of molecular motion • Components of sinusoid • Parts of a wave • Transverse wave simulation • Applet: Square, triangle, simulation • Various Sound applets

  19. Forces of Sound • Inertia – body in motion • Elasticity – restoring force Newton’s Cradle

  20. Hooke’s Law • Law of elasticity is an approximation that states that the extension of a spring is in direct proportion with the load applied to it. • Many materials obey this law as long as load does not exceed material's elastic limit called "Hookean" materials • Hookean materials: broad term including mechanics of vocalis muscles. • Hooke's law in simple terms says that stress is directly proportional to strain. • Mathematically, Hooke's law states that: F= -kx • YouTube video of Hooke’s Law • YouTube video of vibrating vocalis muscles

  21. Components of Sound Wave • Amplitude • Frequency – number of cycles per second • Period – time to complete one cycle • Wavelength – distance traveled in one cycle Pendulum Simulation Sounds in Air Sims

  22. Examples • Piano Note • Timbre • Physics of Sound • The Missing Fundamental Effect • Pitch as a linear scale • Octave effect • Piano Octaves • Pitch as a helix • Pitch chroma circle • Shepard tone • Endless staircase - visual illusion • Endless staircase - Shepard illusion • Shepard discrete steps [wav] [mp3] • Risset continuous change [wav] [mp3]

  23. Pure Tone/Sine Wave/Sinusoidal

  24. Waveforms & Line Spectrums

  25. Waveforms & Envelopes

  26. Length/Mass/Tension and Frequency • Length • Mass • Tension

  27. Phase

  28. Interference • Interference • Constructive • Destructive • Fourier analysis

  29. Sound Waves • Simple • Complex Periodic • Fundamental • Harmonics • Complex Aperiodic • Aperiodic

  30. Waveforms and Spectra • Fourier Analysis of waveforms

  31. Damped Waveforms

  32. Psychoacoustics • Intensity (dB) Loudness (phons) • Frequency (Hz) Pitch (mels) • Time Duration

  33. Resonance • Natural frequency • Resonant frequency • Mechanical • Acoustic

  34. Resonate a Wine Goblet • YouTube 1 • YouTube (Mythbusters)

  35. Resonators as Filters • Bandwidth • Regularly shaped acoustic resonator • Narrowly tuned and lightly damped • Irregularly shaped acoustic resonator • Broadly tuned and heavily damped • Cutoff frequencies • Resonance curves • Center frequency • Types of filters • Low pass • High pass • Band pass • Low/High Pass Filter Example (on computer)

  36. Resonators

  37. Acoustic Resonators/Bandwidth

  38. Question Is the human vocal tract: • A regularly shaped tube • An irregularly shaped tube

  39. Question Which instrument would be more finely tuned? • Flute • Tuba • Saxophone • French horn

  40. Narrow vs. Broad Filter

  41. Question What do we consider the upper and lower cutoff frequency? • 6 dB down from center frequency • 3 dB down from center frequency • 5 dB down from center frequency • 9 dB down from center frequency

  42. Filters - Bandpass

  43. Filters • Low pass filters (cut the high frequencies) • High pass filters (cut the low frequencies) • Band pass filters (cut high and low) • YouTube filters

  44. Passband Resonator

  45. Bandpass Filter • Filter Simulation

  46. High Bandpass earmold tubing Low Bandpass earmold tubing Bandpass Tubing/Hearing Aids

  47. Bandpass/Earhooks • High and Low Pass Filters

  48. Bandpass/Speech Mechanism • Modeling Speech

  49. Question600, 900, 1200 Hz What is the missing fundamental in this example? • 30 Hz • 60 Hz • 100 Hz • 200 Hz • 300 Hz

More Related