Diandra's Video

An earful by Dennis Hong and David McInerney

Definitions
Ear – 1. the organ of hearing and balance in humans 2. the faculty for discriminating sounds.
Hearing – the faculty of perceiving sounds. 2. the range within which sounds may be heard.
Decibel – a unit expressing the intensity of sound.
(Oxford Canadian Dictionary of Current English, Oxford University Press, 2005)

How the Ear works
1. There are three main areas: the outer, middle and inner ear.
2. The outer ear (the part we see), is located from the ear canal to the ear drum, and catches sound in a form of sound wave.
3. The middle ear then turns that wave into a vibration.
4. Vibrations are then passed to the small bones of the middle ear, which transmit the vibrations to the hearing nerve of the inner ear.
5. The vibrations become nerve impulses and go directly to the brain, which interprets the impulses as sound.
(http://www.entnet.org/healthinfo/ears/ear.cfm)


(Source - http://www.vestibular.org/images/ear_diagram_lg.gif)

What did you say? Could you please repeat - LOUDER?!?!

Our ears are very sensitive, complex organs that we must consider when designing for the human experience. Everyday tasks such as listening to an MP3 player, working in shops with loud machinery, crossing a busy street, going to a nightclub or concert, catching a plane or riding the subway; may all cause long-term damage to your ability to be able to hear.

A decibel (dB) is a unit of measurement that indicates the relative amplitude of a sound. The zero on the decibel scale is based on the lowest sound level that the healthy, unimpaired human ear can detect. Sound levels in decibels are calculated on a logarithmic basis. An increase of ten decibels represents a ten-fold increase in acoustic energy, while 20 decibels is 100 times more intense, 30 decibels is 1,000 times more intense etc. Below is a table that shows the intensity of various activities on our ears.


(Source www.ci.redwood-city.ca.us/cds/planning/precise/pdf/ISND/AppendixCNoiseReport.pdf)

The Nose and How We Smell

By Diandra, Patirica, Jennie and Julian



In order to smell, we first have to inhale molecules. These molecules can come from anything, but are usually from objects that have a high molecular volatility – that is they shed their outer molecules into the air inside of being bound. Inside your nose a patch of neurons that are exposed to air inside the nasal cavity, unlike other neuron endings in your body. They have small cilia covering them, which then capture the drifting molecules that you inhale and cause the smell sensation.

Each receptor and cilia is designed to react to a specific molecular and chemical composition. There are several conflicting theories about how exactly the olfactory (smell) sense works. Some posit that neurons and receptors are keyed to acknowledge a specific feature in the chemical compound they absorb, however Vibration theory operates under the assumption that the receptors can actually tell the oscillation of the electrons inside the molecular structure.

Humans tend to have a relatively weak sense of smell compared to similarly sized mammals, and have the least sensitive sense of smell out of all primates.

Gilad Y, Man O, Pääbo S, Lancet D (2003) Human specific loss of olfactory receptor genes. Proc Natl Acad Sci U S A 100:3324–3327.
Turin, Luca. (1996). A spectroscopic mechanism for primary olfactory reception. Chemical Senses, 21, 773-791.

Buck, Linda and Richard Axel. (1991). A Novel Multigene Family May Encode Odorant Receptors: A Molecular Basis for Odor Recognition. Cell 65:175-183.

Touch- by Joanne and Shona

Here is what our crack team of researchers discovered about how the sense of touch works:

Stimulus is sensed through the skin by a nerve ending located in the 2nd layer of our skin, callled the dermis. The stimulation of the nerve creates an electrical impulse that runs down the nerve to the central nervous system located in the spinal cord (missing from the mental model we drew on the board last week). From there the signal travels up the spinal cord to the cerebral cortex in the brain where it is interpreted.
The electrical impulse created from touching something rough is different from the electrical impulse created by something smooth, and hence the brain can distinguish between the two. There are different kinds of receptors to sense different sorts of stimuli. Heat, cold, heavy pressure and light pressure, are all sensed by different types of nerve endings. An overstimulation of any one of these nerve receptors will be registered as something between tickle, itch or pain.
Other fun facts:
-the parts of the body with the most nerve endings are: tongue, lips, face, neck, fingertips, hands and feet.
-the least amount of nerve endings are found in the middle of the back.
-somatic sense: more complete term used in medicine that describes the sense of touch described above, but also includes the sensations we have of the inside of our bodies, such as muscle movement, joint position and stomachaches.

Sources:
"mechanoreception." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 13 Jan. 2008 <http://search.eb.com/eb/article-64717>.
http://library.thinkquest.org/3750/touch/touch.html

Hearing for Dummies Gillian, Gio & Kaylyn

The Ear

 

To understand the ear we must comprehend what sound is. Let’s mentally picture an object in a room on one side, and a big giant ear on the opposing side. When this object produces ‘sound’ it in fact vibrates.

 

There are three basic steps for your ear to hear sound.

 

1)    Sound waves must be directed towards the ear.

2)    The ear senses fluctuations in air pressure.

3)    These fluctuations are then turned into an electrical signal that the brain comprehends.

 

The ear is considered an extraordinary organ. This organ is able to pick up sounds in a surrounding area and translate them into information your brain understands. Sound reaches our ears as waves. Hearing is totally mechanical, where as taste, touch, and vision all involve chemical reactions. 

Extra facts:

 

-       hearing is the second sense developed in the womb after touch.

-       Music activates every region of the brain that we’ve so far mapped.

-       Sense of hearing is a product of evolution (developed to help us survive) it orients and informs of events behind, around corners and any other places we can’t see.

-       These days we shut out nose with our own audio environment (MP3 players, iPods)

-       A healthy cochlea is lined with 3000 tiny hairs which act as sounds receptors whereas a cochlea implant takes sound and digitizes it with only 9-12 nodes.

-       our human speech acts as a sound source, which our brain recognizes as our ears get atuned to the harmonic structure or music an pitch trajectory

Collective Mental Model of the Senses

Here's your collective mental model of the senses, for reference in Exercise Zero.

Exercise One

In the first class, your Project One group developed a mental model for one of the senses, to the best of your knowledge. Expand your knowledge by researching the sense in question, and post the results of your research to the blog.

Make your post succinct. It should no more than three paragraphs, and should make use of images where appropriate. Specifically identify any misconceptions in the mental model developed in class and correct them.

This post must be made by the end of the day on Tuesday, January 15th. Please include the name of all of your group members in your post.

Exercise One: Sight

SIGHT
Miriam , Kristen and Iliana

The eye works in a similar procedure as a camera. Light bounces off objects and into our eyes. Light goes through a
CORNEA
The transparent part at the front of the eye through which light passes, called the cornea.
IRIS
Behind the cornea is a round barrier, called the iris. It is different colours depending on the person.
PUPIL
A hole in the centre of the iris, called the pupil. Light passes through the hole to get into the eye. The pupil size changes according to the amount of light.
FOCUS
When an object is viewed in focus it will cause a clear, sharp image. While an object which is out of focus is blurry and is not seen in detail.
LENS
It is a transparent disk located behind the pupil, called the lens. The lens is connected to the eye with muscles, which causes it to change shape vaguely. Therefore it can change according to the distance between the eye and the object to keep the image in focus.
RETINA
Light beams reach the lining at the back of the eye, which is the retina. It acts just like film in a camera.
OPTIC NERVE
The light beams which have fallen on the retina are turned into electrical nerve signals, which travel down the optic nerve towards the brain.


RESOURCES
Text: http://jim.leeder.users.btopenworld.com/LHON/eye.htm
Image: http://www.spec2000.net/images/eyeball.jpg