Speech and Hearing Science- Chpt. 1, 8, & 9

Science

a system of knowledge covering the operation of general laws obtained and tested through the scientific method

PPhysics

science that deals with matter, energy, motion, and force

Acoustics is a branch of _______

physics

acoustics deals with the…

production, control, transmission, reception, and effects of sound

Bioacoustics

combo of biology and acoustics

• sound production and perception in animals and humans

Mass (m)

amount of matter in an object

• kg

Force (F)

an influence which causes an object to change speed, direction, or shape

• newtons

Weight

the force of gravity on an object as it relates to the mass

• newtons

volume

quantity of a 3D space occupied by a liquid, solid, gas

• liter

density

mass of a substance, material, or object per unit of volume or mass divided by the volume

• cm³, kg/m³, g/mL

speed

distance an object travels in a given time

• specifies the direction of the movement

momentum

mass times velocity of an object during motion.

• greater mass = greater momentum

• change in mass/velocity = momentum

acceleration

occurs when velocity changes as a function of time

• with constant force

• greater mass = smaller acceleration

inertia

resistance of any physical object to change in its state of motion or rest

• force must be applied

Elasticity

property of a material that returns it to its original shape after it has been deformed by an external force

• influenced by stiffness as this serves as a resistance to the elastic body

pressure

the force acting perpendicular on a specific surface are

• measured in pascal (Pa) or units of cm H2O

Brownian motion

the random movement of molecules of air

air pressure

a force that acts perpendicularly on a surface

• P

airflow

the movement of air through a particular area in a certain interval of time

• measured in L or mL per sec/min

• rate of flow is volume velocity

two types of air flow and example

laminar and turbulent

• ex) river with rocks

Boyle’s law

increase volume = decrease pressure and vice versa

• how air enters lungs

Hooke’s law

The restoring force is proportional to the distance displacement and acts in the opposite direction

friction

a force that opposes motion

wavelength

• Measurement of the distance traveled by a sound wave

• the distance in meters or centimeters covered by one complete cycle of pressure change

higher frequency of a sound means…

the more cycles per second

• vice versa

pure tones

a sound of a single frequency

• has a thin quality

  • tuning fork

complex sounds

waves that consist of two or more frequencies and occur when waves of different frequencies combine with each other

Frequency

one back-and-forth movement. The number of cycles per second is termed frequency

• measured in hertz

Lowest frequency of the sound called?

fundamental frequency (F0)

The frequencies above the fundamental frequency called?

harmonic frequency

complex periodic waves

• has a musical tone and specific pitch

• sounds richer and more resonant than a pure tine wave

aperiodic complex wave

consists of two or more frequencies (frequencies are not systemically related to each other) Noise without pitch

• ex) steam, applause

frequency and pitch

the perception of the frequency of sound is reffered to as the pitch

Amplitude, intensity, and loudness

the distance air molecules are displaced from their rest positions during vibrations

• Amp is like in math and the higher the amp the louder the sound

• measured in decibels

Hearing range for humans (Hz)

20-20,000

subsonic frequencies

frequencies below what humans can hear

super-sonic frequencies

frequencies above what humans can hear

How decibels work and our perception of them

for every 10 dB increase, the sound seems to double in volume

• 70 dB is twice as loud as 60 dB

• dB do not have a 1:1 ratio with amplitude.

  • every increase of 6 dB is a doubling of amp physically, but or humans to perceive it as doubling it needs to be a 10 dB increase

dB humans can hear

0-140

Threshhold of hearing

softest sound a patient can hear at a specific frequency 50% of the time

threshold of pain

about 130 dB at any frequency will cause pain

What does an audiogram measure

a patient’s hearing by their threshold at selected frequency levels

what are on the x and y-axis of an audiogram

x = frequency

y = intensity

incident wave

a sound wave generated by a vibrating source

• may be transmitted, absorbed, refracted, or diffracted

abosrbtion

the dampening of a sound wave with diminishing changes in air pressure.

reflection

some portion of the sound that is not transmitted or absorbed bounces back from the surface and travels back in the opposite direction

Refractions

when sound waves chance direction because of a local difference in air temperature

• temperature differences will cause the wave to refract (bend) towards the cooler air

Defraction

a change in direction as a wave passes through an opening or travels around an obsticle.

• longer wavelengths = easier to pass around objects (elephants using lower frequencies to comunicate)

The type of energy each part of the ear uses

• outer: acoustic

• middle: mechanical

• inner: fluid

The ear acts as a…

transductor

• converts energy from one form to another

What is the outer ear made of

• pinna

• external auditory meatus (ear canal)

What does the pinna do?

• channel sound waves

  • especially high frequency sounds

• protects entrance

• direction of sound

external auditory meatus

• from pinna to ear drum

• lined with epidermis

• contains cerumen (lubricates ear canal & protect against insects)

• boosts amplitudes of high-frequency sounds

How long is external auditory canal?

• 1 in long

• 9mm in height

• 6.5 mm wide in adults

outer portion of external auditory canal

• passes through cartilage

• produces wax

• contains hair cells

inner portion of external auditory canal

• passes through temporal bone

• no glands or hair

• outer and inner portion meet at the osseocartilaginous junction

umbo

tip of the cone (ear durm) which faces the middle ear

ossicles

malleus, incus, and stapes

• attached at umbo and eventually oval window

Eustachian tube (know all)

• connects middle ear to the back of the throat and nose

• function: keeps middle ear ventilated and drained

• equalizes air pressure

• helps clear mucous by draining the mucus from the pharynx

What happens if Eustachian tube can’t drain/open?

pressure becomes unbalanced and negative (blocked hearing)

• can lead to middle ear infection

slide 18 of chapter