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Types of Sound Waves • There Are 2 types of sound waves • Amplitude: Height of the Sound Wave • Frequency: Number of Sound Waves Per Second Amplitude • Large Amplitude: Means Big Sound Waves and loud sounds • Small Amplitude: Means small sound waves and soft sounds Loudness • Loudness: Is your subjective experience of a sounds intensity • The brain calculates the amplitude of sound waves Measuring Sound Waves • Loudness is measured in Decibels • 0 Decibles (Absolutely no sound) • 140 Decibles (Can produce pain and hearing loss) • 140-Jet Engine, Gun Muzzle Blast • • 120- Rock Concert, Human Yell (115db) • • 100-Chainsaw, Jackhammer, baby screaming, Firecracker • Expose for 2 hours can cause hearing loss • 80-Heavy City Traffic, Alarm Clock at 2 feet, Subway, Personal tape recorder • Constant Exposure for 8 hours can cause hearing loss • 60-Conversation, Air Conditioner at 20 feet, typewriter • 30- Whisper, Quiet Library, Car Idling in Neutral (45db) • 0- Threshold of Hearing Any Exposure is Painful and Dangerous Exposure for 15 minutes of less can cause hearing loss Hearing Range • Humans only hear sounds within certain frequencies This range decreases with age • As an Infant we hear frequencies from 2020,000 cycles per second. Frequency and Pitch • As the Frequency increases the pitch goes up (High Note) • As the Frequency decreases the pitch goes down (Low Note) Parts of the Ear • External Ear – Pinna: A sound collecting cone – Auditory Canal: Funnels sound to the eardrum – Tympanic Membrane: Passes Vibrations on to the middle ear • Middle Ear: Is a bony cavity that is sealed at each end by membranes. • The Two membranes are connected by three small bones called Ossicles (Hammer, Anvil and Stirrup) • The purpose of the middle ear is to amplify the vibrations and pass them on to the oval window The Inner Ear • Contains two main structures that are sealed in bony cavities • The Cochlea: Which is involved with hearing • Vestibular System: Which is involved with balance The Cochlea • Bony Coiled Exterior • Contains the hearing receptors (Transforming vibrations into nerve impulses) • Neural Tissue of the Brain The Cochlea • Divided into an upper and lower chambers • Each chamber is lined with a basilar membrane • The basilar membrane holds the auditory receptors called hair cells (cells that stick up from the basilar membrane) • Neural impulses are sent to the Thalamus (Relay Center) and then to the Primary Auditory Cortex (located in the Temporal Lobes) Pitch Perception • Frequency Theory: Applies only to low pitch sounds, says that the rate at which a nerve impulses reach the brain determines how low the pitch is. (Like a Drum) • Place Theory: says that the brain determines medium to higher pitch sounds on the basis of the place on the Basilar Membrane where maximum vibrations occurs. (Like strings on a Harp) • Just like the Two Color Vision theories experts believe that we use both theories to perceive pitch Vestibular System: Balance • Is located above the Cochlea in the inner ear • Includes 3 semicircular canals which are set at different angles filled with fluid • In the canals there are sensors (Hair Cells) that respond to the movement of the fluid • The function of the vestibular system include sensing the position of the head, keeping the head upright, and maintaining balance Motion Sickness, Meniere’s Disease and Vertigo • Motion sickness: results when information provided by the vestibular system doesn’t match information coming in from other senses. Symptoms include, dizziness, nausea, vomiting. • Meniere’s Disease: Symptoms are more severe than motion sickness and also include head splitting buzzing sounds, however, unlike motion sickness, this is caused from a malfunction of the semicircular canals. This is thought to be caused by a viral infection. • Vertigo: Shares the same symptoms of Meniere’s Disease and both have no known cures. The cause of Vertigo is unknown. Chemical Senses • Gustatory System: (Taste) Taste is called a chemical sense because the stimuli are various chemicals. On the surface of the tongue are taste buds. The function of taste buds is to perform transduction, which means transforming chemical reactions into nerve impulses. • Taste Buds: Sweet Salty Sour Bitter Umami (a meaty-cheese taste) • All Tongues are not equal • In rare cases people are born without taste buds • 25% of the population are supertasters, which means they have two to three times more taste buds than normal (More sensitive to bitter and sweet and spicy foods) • Flavor: (comes from combining our sense of taste with our sense of smell) • Obviously taste preference is heavily influenced by our environment Smell • Olfaction: is a chemical sense because its stimuli are various chemicals that are carried by the air • The upper part of the nose has a small area that contains receptor cells for olfaction. • The function of the olfactory receptors is transduction, or to transform chemical reactions into nerve impulses • Olfactory Cells are receptors for smell and are located in the uppermost part of the nasal passages • Theses cells are covered with mucus, a gluey film into which volatile molecules dissolve and stimulate the underlying olfactory cells • Helps us taste food, Warns us of potentially dangerous foods, Attracts a Mate Touch • The Somatosensory Cortex, which is located in the Parietal Lobe transforms nerve impulses into sensations of touch, temperature or pain • Pain: is an unpleasant sensory and emotional experience • Pain is essential for survival: it warns us to avoid or escape dangerous situations or stimuli and makes us take time to recover from injury • Mind over matter (pain): Gate Control Theory says that nonpainful nerve impulses (shifting attention) compete with pain impulses in trying to reach he brain. This competition creates a bottleneck, or neural gate, that limits the number of impulses that can be transmitted. The neural gate isn’t a physical structure but rather refers to the connection between nonpainful and painful impulses as they try to reach the brain. • Your body also produces pain-reducing chemicals called endorphins. What kind of drug mimics endorphins? (Opiates such as morphine, heroine, codeine)