1 / 13

What do we hear?

What do we hear?. Sound is a compression wave - it only “looks” like a wave if we plot air pressure against time. Period - amount of time for one cycle. Frequency = number of cycles per second (1/Period). Air Pressure. time ->. Sensing Vibrations. Inside the cochlea is the basilar membrane

armand
Télécharger la présentation

What do we hear?

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. What do we hear? • Sound is a compression wave - it only “looks” like a wave if we plot air pressure against time Period - amount of time for one cycle Frequency = number of cycles per second (1/Period) Air Pressure time ->

  2. Sensing Vibrations • Inside the cochlea is the basilar membrane • Movement of the oval window causes ripples on the basilar membrane

  3. Hearing • Detection • Loudness • Localization • Scene Analysis • Music • Speech

  4. Detection and Loudness • Sound level is measured in decibels (dB) - a measure of the amplitude of air pressure fluctuations

  5. Detection and Loudness • Sound level is measured in decibels (dB) - a measure of the amplitude of air pressure fluctuations • dB is a log scale - small increases in dB mean large increases in sound energy

  6. Detection and Loudness • Sound level is measured in decibels (dB) - a measure of the amplitude of air pressure fluctuations • dB is a log scale - small increases in dB mean large increases in sound energy • We have a dynamic range that is a factor of 7.5 million!

  7. Detection and Loudness • minimum sound level necessary to be heard is the detection threshold

  8. Detection and Loudness • detection threshold depends on frequency of sound: • very high and very low frequencies must have more energy (higher dB) to be heard • greatest sensitivity (lowest detection threshold) is between 1000 hz to 5000hz

  9. Detection and Loudness • Detection can be compromised by a masking sound • even masking sounds that are not simultaneous with the target can cause masking (forward and backward masking)

  10. Detection and Loudness • Loudness is the subjective impression of sound level (and not identical to it!)

  11. Detection and Loudness • For example, tones of different frequencies that are judged to be equally loud have different SPLs (dB)

  12. Detection and Loudness • Hearing loss due to exposure to high-intensity sounds (greater than 100 dB) is frequency-specific and can last many hours

  13. Detection and Loudness • Incidence of noise-related hearing loss is increasing dramatically • iPods and other “earbud” music players are thought to be partly responsible • How loud is an iPod? • maximum volume is approximate but is somewhere between 100 dB (hearing damage in about 2 hours) to 115 dB (hearing damage in about 15 minutes) • Consequences: difficulty understanding speech, tinnitus, deafness • Your perception of loudness adapts so it’s hard to tell how loud your iPod is - LOCK THE VOLUME ON YOUR iPOD!

More Related