Ch 2 (MIDTERM) Flashcards
Amplitude
uPA
Pressure change generated
Std reference: 20uPA
INtensity
W/m^2
Power of sound over an area
Representation of amplitude
std. reference: 10^-12 W/m^2
Loudness
Psychological construct of intensity
Greater amplitude, greater intensity, greater loudness
dB scale
Logarithmic ratio scale
Compresses large range of decibels into a scale with fewer levels (logarithmic exponential)
Compares the amplitude of any sound to its standard reference
Standard Reference
Softest a typical majority can hear 50% of the time under ideal conditions (i.e. threshold)
Threshold of hearing
What somebody can hear 50% of the time under ideal conditions is their threshold
0dBSPL = 20uPA, not zero sound since the reference is the starting point
Important aspects of dB
Ratio, not straight metric
Logarithmic increase, not linear
Various reference points
dB IL
Intensity level
Measurement of power with reference of 10^-12W/m^2
Std. ref: 10^-12W/m^2
dbIL= 10log(I1/10^-12W/m^2)
Special:
When intensity doubles, decibels increase by 2dB
dB SPL
Sound pressure level
Measurement of pressure with std. reference of 20uPA
More often used by audiologists
std. ref: 20uPA
dBSPL= 20log(P1/20Upa)
Special: When SPL doubles, increase by 6dBSPL
dB HL
Hearing level
Human ear does not respond to all frequencies equally sensitive
needs different uPA to hear different frequencies at the typical threshold
Different frequencies need different intensity to reach typical threshold for that frequency
Lowest intensity the typical majority can hear at a certain frequency
Std. ref: depends on frequency
Audiometric zero, zero on audiogram is dBHL threshold
Speech frequency
250-8000Hz
Has the lowest dB HL
dB SL
Sensation level
Threshold is the specific patient’s threshold and what they can hear at different intensities
zeroes out on where individual can hear 50% of the time
Sound damaging to ear
10^2W/m^2 or 2x10^8uPA
