Study guide for Exam 1
Know the characteristics of a sine wave:
frequency- cycles per second, Hz. Perceptual correlate is pitch. Human range from
period- P= 1/frequency (Hz), amount of time for one cycle to be completed.
amplitude- measured in dB, perceptual correlate is loudness. Human range is from
0-120 dB SPL
phase- where the cycle starts, no perceptual correlate, important for complex sounds.
wavelength- amount of space cycle takes up, (speed of sound)/ frequency (Hz)
Know the properties a medium must have to transmit sound -
Must have mass and is compressible (elastic)
Know the meaning of:
spectrum - The interaction of intensity and frequency in complex sounds.
RMS pressure - The root-mean-square pressure (abbreviated as rms pressure) is the
square root of the average of the square of the pressure of the sound signal over a
decibel- describes intensity (correlate of loudness) as a logarithm of a pressure
and a reference pressure.
Know the components of impedance (there are 3)-
Resistance - independent of frequency
Mass Reactance- reactivity goes up as frequency goes up
Stiffness Reactance reactivity goes down as frequency goes up
Stiffness and Mass Reactance are 180 degrees out of phase
what component dominates at low frequencies (below the resonant frequency) what
component dominates at high frequencies (above the resonant frequency)-
Know why the outer ear resonates at the frequency that it does-
Our auricle is shaped in a way that helps us with sound localization and amplifies
frequencies near 4500 Hz. A resonator is a system which is set into vibration by another
system. Auricle being vibrated by sound.
Know the following for dB SPL, dB HL:
Reference of dB SPL: dynes/cm or micropascals (µPa)
Reference of dB HL: average normal hearing (audiometric zero)
What each is useful for?
dB SPL: Used to determine
dB HL: represents decibels according to average normal hearing.
What do average normal human thresholds look like on a plot of:
dB SPL v. frequency-
dB HL v. frequency-
You will not have to calculate dB for this exam!!!
Anatomy and physiology
Know the structure of the outer, middle, and inner ear to the degree discussed in class-
What is the impedance mismatch between the outer and inner ears, and what is the
main way in which the middle ear overcomes it?-
energy towards smaller area of stapes foot plate which increases pressure delivered to
Lever Ratio between manubrium of malleus and incus
What is tonotopic coding?
What are the functions of the IHCs, OHCs, basilar membrane and tectorial membrane in
the inner ear? There will definitely be a question on the role of the IHCs vs the OHCs!!!
▯ OHC’s- elongated, and have cilia at top. cilia embedded in tectorial membrane.
innervated by efferent (motor, going from brain to body). Produce force at the present of
low intensities and displaces the tectorial membrane so that it increases IHC sensitivity.
IHC’s- innervated by afferent fibers (to brain) , sensory
Know some sounds that you normally hear partly through bone conduction-
Any noise we make with our own vocal tract
Know what the method of limits and the method of constant stimuli are. Which one is
Method of Limits - Task: Detect a Tone. Person must respond when they hear sound.
Adjust level un