The Profession of Audiology (1) and Hearing Science Review (2)

What is audiology?

a field of research and clinical practice devoted tot he study of hearing disorders, assessment or hearing, hearing conservation, and aural rehabilitation

audiologist

• -a health professional with graduate education who identifies, assesses, diagnoses and treats persons with impaired auditory or vestibular (balance) systems and works to prevent impairments or these systems

  • -we study, diagnose, and treat persons with impaired auditory or balance systems, and work to prevent impairments of these systems

where did audiology begin?

concentrated affor to assists hearing-injured WWII veterans reentering civilian life

scope of practice

-audiometric evaluations and treatment or management of hearing impairment, disability and handicap

-fitting hearing aids, assistive listening devices, etc.

-auditory-verbal therapy

compression (of sound wave)

the portion of a sound wave where the molecules of the medium are compressed together (a.k.a. condensation)

rarefaction

the portion of a sound wave where the molecules become less densely packed

frequency

the number of complete oscillations of a vibrating body per unit of time (cycles per second)

expressed in Hz (Hertz) after Heinrich Hertz (German physicist made contributions to electromagnetism)

cycle

once cycle of a sin wave is one compression (peak) and one rarefaction (trough)

period

the time in seconds it takes to compete 1 cycle of vibration (1/frequency)

frequency/period

higher frequency = shorter period

lower frequency = longer period

wavelength (lamda)

the length of a wave from any point on the sinusoid to the same point on the next cycle of the wave (must include one peak and one trough)

velocity/frequency (in Hz)

velocity (V) = speed of sound

amplitude

the magnitude of an air particle’s displacement (more power=bigger amplitude)p

phase

the description of your location at any point in time in your particle displacement

also used to describe the relationship in time between two or more waves

starting phase

the starting point of a waveform

out of phase

if an oscillation begins at 0 degrees or 360 degrees, it is said to be ‘in phase’

complex wave

a sound wave made up of a number of different sinusoids, each with a different frequency

interactions

when more than one tone is introduced, there are interactions among sound waves:

-frequency

-intensity

-phase relationship

same frequency/phase

will add together

will increase amplitude

same frequency/out of phase

same frequency BUT 180 degrees out of phase

-will cancel each other out

-zero amplitude

physical properties of sound

sound is a series of disturbances of molecules within a medium (objective event)

psychological properties of sound

-an auditory experience

-requires that an organism process the acoustic energy: the act of “hearing” something

-subjective event

physical properties of sound

-frequency

-intensity

-complexity

psychological properties of sound

-pitch

-loudness

-timbre

frequency measured in:

-Hertz (Hz) or cycles per second

pitch is measured in:

Mels

-the relationship between Hz and Mels is ONLY 1:1 at 100Hz (not constant across all frequencies)

humans respond to frequencies between:

20 Hz to 20,000 Hz

most energy in speech is located between

250 Hz and 8000 Hz

intensity (loudness)

amplitude of vibration

-amount of sound energy per unit of area

-indication of power of a sound

intensity measured in:

decibels or dB

loudness measured in:

Sones or Phons

loudness

the sensation we experience as a result of intensity

the loudest sound the human ear responds to is _____ times more intense than the softest sound

10,000,000 times

complexity

pertains to sounds containing energy at several different frequencies, intensities, and phase relationships

timbre

the perceived sound quality of complexity (frequencies, intensities, and phase relationships)

Decibel (dB)

a unit for expressing the ratio between two sound pressures or two sound powers

-a measure of intensity

-scale is in logarithms (10¹, 10², etc)

-we CAN’T add decibels

types of dBs

-dB SPL

-dB HL

-dB SL

dB SPL

-Sound Pressure Level

-the actual, physical measurement of the pressure of a sound at a given frequency

-measured using a sound level meter

-not used clinically

dB HL

-Hearing Level

-needed to develop a scale that was more clinic-friendly

-American National Standards Institute (ANSI) developed

-the number of dB above an average normal threshold for a given signal

the hearing level dial on the audiometer is calibrated in dB ___

dB HL

using dB HL allows us to….

easily plot how far outside the range of normal a person’s hearing is across frequencies

dB SL

-Sensation Level

-the number of decibels above the hearing threshold of a given subject for a given signal

-completely relative to individual being tested

-subtract the threshold dB HL form the dB HL of the presented signal