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Sound and Hearing

This article explores the concept of decibels (dB) and their role in measuring sound pressure levels, compressing a wide range of pressures into manageable units. It explains the decibel scale, ranging from barely audible sounds at 0 dB to the intensity of a jet engine at 140 dB. The piece also delves into the three primary dimensions of sound sensations—pitch, loudness, and timbre—and their associated physical dimensions, such as frequency and amplitude. Key auditory structures and pathways in the ear are also discussed, highlighting their importance in sound perception.

stephanie-ellison
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Sound and Hearing

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  1. Sound and Hearing

  2. Decibels dB = 20log(P1/Po) P = amplitude of the sound wave Po = reference pressure = 0.0002 dynes/cm2 Decibels compress the large range of possible pressures into more manageable units Converts a range of 0.0002 (threshold pressure) to 2,000 (jet at take off) to a range ofr 0 to 140 dB

  3. _____________________________________________________ Sound SPL (dB) _____________________________________________________ Barely audible sound (threshold) 0 Leaves rustling 20 Quiet residential community 40 Average speaking voice 60 Loud music from radio/heavy traffic 80 Subway 100 The Rolling Stones 120 Jet engine at takeoff 140 _____________________________________________________

  4. Sine Wave

  5. 90° out of phase

  6. 180° out of phase

  7. Three primary dimensions of sensations associated with sounds with periodic waveforms Pitch, loudness and timbre. Pitch - sensation of "altitude" or "height" of a tone. Loudness - sensation of "intensity" of a tone. Timbre - quality of a sound.

  8. Psychological Dimension Associated Physical Dimension Pitch Frequency Loudness Amplitude Timbre Spectrum

  9. Middle Ear

  10. Inner Ear

  11. Organ of Corti

  12. When sound causes the basilar membrane to deflect upward, the reticular membrane moves up and inward causing the stereocilla to bend outward

  13. Auditory Pathways

  14. Primary and secondary auditory cortex Tonontopic organization - numbers are characteristic frequencies

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