Exam 1- Lectures 1-4 Flashcards
Speed
- Distance traveled by an object in a given unit of time
- -Velocity- specifies direction of movement
Acceleration
- Velocity changes as a fxn of time
- Directly proportional to the force applied
- Inversely proportional to the object’s mass
Elasticity
-The degree to which a material returns to its original shape after it has been deformed by an external force
Pressure
- Force acting perpendicularly on a specific surface area
- Measured in pascal (Pa)
- Patmos= 101.325 kPa
- Pressure in diff locations can be higher or lower than Patmos
- —Increase in air molecules= increase in P
- —Decrease in air molecules= decrease in P
- Volume= inversely proportional to pressure
Acoustics
- Study of sound
- –Propagation of a pressure wave in space and time
- Pressure waves move from states of high to low pressure
- Audible disturbance in a medium such as air, water, metal
- —Medium contains molecules that share characteristics of elasticity and mass
Air Molecules
- Conducting medium of interest for speech
- Number of molecules in a cubic inch of air= density of air (p)
- Average number of air molecules per cubic meter of air= 3x10^23
Force
-Influence that causes an object to undergo a change in speech, a change in direction, or a change in shape
Displacement
- Movement away from resting position
- The generation of a recoiling force
Restoring (Recoil) force
- An opposition to an increase in displacement
- Variable force that gives rise to an equilibrium in a physical state; tends to bring system back toward equilibrium
Inertia
- Resistance to change in its state of motion or rest
- Tendency of objects to move in a straight line at constant velocity
Sound Waves in Air
- All particles go through the same back and forth motion, but the movement of each particle lags slightly behind the movement of the proceeding particle
- The disturbance itself moves along the line of particles
- Air particles move back and forth around their fixed resting position
Sound Wave Definition
-Movement (propagation) of a disturbance through a material medium such as air, w/o permanent displacement of the particles themselves
Simple Harmonic Motion
- A periodic motion where the restoring force is directly proportional to the displacement
- –Restoring force pulls towards resting position; overshoot occurs due to inertia
- Pure tones= SHM
Inertia and Restoring Force within a Cycle
- RF is strong when inertia is weak (when swing is displaced)
- Inertia is strong when RF is weak (around rest position)
- Interplay btwn the two leads to vibration that persists
Pure Tone
- Pattern of vibration= periodic
- Graphic represents a sine wave
- Ex: Tuning forks and pendulums, swings
Periodic
- Each cycle takes the same amount of time
- Frequency and period are constant
Compression
-Area of positive pressure from when molecules approach and collide
Rarefaction
- Area of lower pressure
- Decreased density of air
Propagation
-Changes in pressure continue in a wavelike motion that travels from source of a sound
How does the tympanic membrane vibrate?
-Through changes in air pressure arriving at the ear
Period
- T
- The time it takes to complete one cycle of motion of the molecule throughout the vibratory cycle
Frequency
- Number of cycles per second
- Hz
- Inverse of period; f= 1/T
- –As frequency increases, period decreases
- Pitch= subjective quality related to frequency
Wavelengths
- Measurement of spatial variation of a pressure wave
- Distance covered by one complete cycle
- Inverse relationship to frequency
Damping (Energy Loss)
- As a sound wave travels across a medium, its energy is spread over a larger and larger area, its sound intensity gradually decreases
- Each time molecule moves back and forth, it does so w/ diff amplification
- Ex: friction, absorption