sensation and perception – part ii:
DESCRIPTION
Sensation and Perception – Part II:. Hearing. Amplitude. Frequency. Dude, you’re so sensitive…. Amplitude : “loudness” - determined by the amplitude of sound waves (how tall the waves are) High amplitude, loud sounds. - PowerPoint PPT PresentationTRANSCRIPT
Sensation and Perception – Part II:
Hearing
FrequencyAmplitude
Dude, you’re so sensitive…
• Amplitude:– “loudness” - determined by the amplitude of
sound waves (how tall the waves are)– High amplitude, loud sounds. – “Loudness” is subjective based on how sensitive
your ears are to the amplitude of sound.
Like nails on a chalkboard…
• Frequency:– Refers to how many sound waves occur within one
second.– High frequency, high pitch (sound waves close
together)– Low frequency, low pitch (sound waves far apart)
If you want to instantly improve your hearing, do what your mother tells you and clean out your ears of ear
wax!
True or False?
The wax does not affect your hearing at all! Your ear is literally a hole in your head, and just like boogies in your nose, you need wax to keep it protected from the outside world.
Btw, you don’t ever need to clean out your ears, but sometimes it is
necessary, like before a hot date!
False!
Headphones are only dangerous to your ear health if the volume is too
loud.
True or False?
Yes, loud music causes permanent damage to hearing. But not only
that, using ear buds or noise-cancelling headphones increases the bacteria in your ear by 700x in just
one hour! Yay ear infections!
False!
Measuring Sound
• Amplitude is measured in decibels (dB).– Decibels: scientific units that measure “loudness”
• Humans carry a threshold of 0 dB (absolutely no sound) to 140 dB (pain and permanent hearing loss)
Slide 10
Decibel Level of Some Common Sounds
Decibels Source Exposure Danger180 Space shuttle launch Hearing loss certain within 150
feet of launch pad140 Jet aircraft motor Any exposure dangerous120 Sandblaster, thunderclap,
average Freshmen class in a hallway.
Immediate danger
100 Heavy auto traffic, lawn mower
2 hours
80 Alarm clock, average mp3 player volume
1 hour
60 Normal conversation No danger30 Quiet library No danger20 Soft whisper No danger0 Minimal detectable sound No danger
Babies cry so loud because their hearing is terrible when they are
born.
True or False?
Babies cry for numerous reasons, but definitely not to hear themselves better. Their hearing is actually
much, much better than adolescents or even toddlers. Their hearing
ability decreases over time as other senses improve with normal
child development.
False!
13
The Ear
14
The EarOuter Ear: Collects and sends sounds to the eardrum.
15
The EarMiddle Ear: Chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window.
16
The EarInner Ear: Innermost part of the ear, containing the cochlea and semicircular canals.
17
Inner Ear
• Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory signals.• Semicircular canals: look like little loops; contain fluid that tell your parietal lobe where your head is in relation to gravity.
–This controls your balance and keeping your head upright.–So what’s up with motion sickness and dizziness?
18
Localization of SoundsBecause we have two ears, sounds that reach one ear faster than the other ear
cause us to localize the sound.
19
Localization of Sound1. Intensity differences
2. Time differences
Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as a “shadow” or partial sound
barrier.
Elephants can “predict” an earthquake because they can hear
with their feet.
True or False?
…kind of. Elephants can feel seismic vibrations in their feet over very long distances, which is why they
“trumpet blast” so close to the ground. They can feel an earthquake
way below ground before we humans can!
True!...
You never stop hearing, not even in your sleep.
True or False?
So there’s no reason to miss your wake up alarm! Your ears are
constantly picking up sound, except during sleep your temporal lobe is not actively analyzing the sound.
(“What was that?!”)
True!
Slide 24
Hearing Loss
• There are two types of hearing loss: – Conduction hearing loss– Sensorineural hearing loss
Slide 25
Conduction Hearing Loss
• Occurs when there are physical problems sending sound waves through the outer or middle ear
• Often involves a punctured eardrum or damage to any of the bones in the middle ear
• Hearing aids – Common treatment for conduction hearing– Tiny instruments worn just inside the outer ear– Change sound waves into amplified vibrations and send
them to the inner ear
Slide 26
Sensorineural Hearing Loss • More common than conductive hearing loss• Involves nerve problems in the inner ear• Often occurs because hair cells in the cochlea are
damaged either by disease, injury, or aging• Cochlear implant
– Only means of restoring hearing– Miniature electronic device surgically placed into cochlea– Changes sound waves into electrical signals– Best candidates—young children born with hearing loss