true and false - 11
The acoustical function of the pinna is to concentrate more sound energy into the auditory canal since the sound energy received is inversely proportional to the area of the sound
wave front intercepted.
F
since the eardrum is 15 to 30 times larger than the oval window, it increases 15 to 30 times the effectiveness of reception in comparison with the oval window alone.
T
The three amplification mechanisms in the ear produce an effective amplification of about 280
F
A low frequency wave will peak near the oval window and excite the basilar membrane in that area.
F
The threshold of human hearing occurs at a sound intensity of about 10^-16W/cm2 (10^-14 W/cm2) at 10^3 Hz.
F
Since the sound intensity is proportional to the square of the amplitude of pressure variation above and below Patm, an intensity level 10^12times the threshold intensity would correspond to 10^9 times the pressure variation at threshold.
F
The frequency range for human hearing varies from 20 to 20 000 Hz.
T
At 10^3 Hz a frequency change of 3 Hz can be heard by most people.
F
The ear is sensitive to absolute frequency changes rather than to frequency ratios.
F
Besides the ability to distinguish between sounds of different pitch and intensity, the ear can distinguish between sounds of different quality only if they have the same pitch and intensity.
T
The logarithm to the base 10 is defined as power to which you must raise 10 to get the number.
T
If the sound intensity is 10^4 W/m2, then the relative intensity is 100 dB.
F
Sound intensity is defined as the acoustic power per unit area per unit time. It is an objective physical characteristic which does not depend on the frequency of the sound.
T
For a 100 Hz sound the loudness in phons and the intensity in decibels are always numerically equal, since 100 Hz is selected as the international standard frequency.
T
According to the equal loudness curves, the threshold of hearing is zero phons, regardless of frequency
T
At a constant frequency, an increase in intensity will decrease the perceived loudness
F
The sensitivity of human ear varies less with frequency for very loud sounds.
T
Pure tone audiometry has some advantages in comparison with speech audiometry since pure tones are the most important sounds which we must understand
F
The usual devise used to measure environmental sound is a sound-level meter with a standard contour filter which discriminates against low and high frequency sounds.
T
The energy of sound waves transmitted to the cochlea fluid activates nerve endings along the basilar membrane, and the perceived pitch is determined by the area of maximum
excitation along this membrane.
T
Sounds of equal intensity but different frequencies may be perceived to have different loudness.
T
The decibel scale actually represents the product of a sound intensity and standard threshold intensity.
T
Sound quality is mainly determined by the number and intensity of higher frequencies present in the sound.
T
Testing for hearing loss is referred to as relative intensity.
F
When comparing two sound intensities, the range of differences is so great that a logarithmic comparison scale is used.
T
The human ear is more sensitive to sounds in the frequency range 1 kHz to 4 kHz than to very low or high frequency sounds.
T
The frequency range from 2000 to 6000 Hz is the most important for speech understanding.
T
Sound waves in fluids are longitudinal waves, i.e. fluid molecules vibrate along the axis of sound propagation.
T
Loudness is an objective sound characteristic.
F
Beats occur as the result of a superposition of two sound waves of slightly different frequency.
T