Biomedical Instrumentation Questions and Answers – Measurement of Hearing

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This set of Biomedical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “Measurement of Hearing”.

1. Pure-tone audiometers usually generate test tones in octave steps from ___________
a) 125 to 800 Hz
b) 125 to 8000 Hz
c) 25 to 8000 Hz
d) 15 to 800 Hz
View Answer

Answer: b
Explanation: Pure-tone audiometers usually generate test tones in octave steps from 125 to 8000 Hz, the signal intensity ranging from –10 dB to +100 dB. Pure-tone audiometry is used in routine tests and, therefore, it is the most widely used technique for determining hearing loss. Pure-tone audiometry has several advantages, which makes it specifically suitable for making threshold sensitivity measurements. A pure-tone is the simplest type of auditory stimulus. It can be specified accurately in terms of frequency and intensity.
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2. Speech audiometry normally allows measurements to be made within the frequency range of _____
a) 300–3000 Hz
b) 30–300 Hz
c) 300–3000 KHz
d) 3–30K Hz
View Answer

Answer: a
Explanation: Speech audiometry normally allows measurements to be made within the frequency range of 300–3000 Hz. Pure-tone audiometers usually generate test tones in octave steps from 125 to 8000 Hz, the signal intensity ranging from –10 dB to +100 dB. Some patients may have impaired high frequency response due to high intensity level occupational noise at 4000 or 6000 Hz.

3. The signal intensity of Pure-tone audiometers ranging from ______
a) 10 dB to +100 dB
b) –10 dB to -100 dB
c) –10 dB to +100 dB
d) –10 dB to +10 dB
View Answer

Answer: c
Explanation: Pure-tone audiometers usually generate test tones in octave steps from 125 to 8000 Hz, the signal intensity ranging from –10 dB to +100 dB. A wave in the air, which involves only one frequency of vibration, is known as pure-tone. Pure-tone audiometry is used in routine tests and, therefore, it is the most widely used technique for determining hearing loss. Pure-tone audiometry has several advantages, which makes it specifically suitable for making threshold sensitivity measurements.
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4. The frequency range of pure-tone audiometer is more than that of speech audiometer.
a) True
b) False
View Answer

Answer: a
Explanation: It is True. The frequency range of pure-tone audiometer is more than that of speech audiometer. Pure-tone audiometers usually generate test tones in octave steps from 125 to 8000 Hz, the signal intensity ranging from –10 dB to +100 dB. Speech audiometry normally allows measurements to be made within the frequency range of 300–3000 Hz. Pure-tone audiometry has several advantages, which makes it specifically suitable for making threshold sensitivity measurements.

5. ___________ amplifier circulatory is employed to reduce the hum noise generated by the power supply in the ECG circuit.
a) low pass filters
b) high pass filters
c) band pass filters
d) notch filters
View Answer

Answer: d
Explanation: CMRR of the order of 100–120 dB with 5 kW unbalance in the leads is a desirable feature of ECG machines. A notch filter is employed to suppress the hum noise generated by the power supply in the ECG circuit.The instability of the baseline, originating from the changes of the contact impedance, demands the application of the automatic baseline stabilizing circuit.
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6. The unit of sensitivity of an electrocardiograph is ________
a) m/mV
b) mm/V
c) mm/mV
d) m/V
View Answer

Answer: c
Explanation: The unit of the sensitivity of an electrocardiograph is mm/mV. The sensitivity of an electrocardiograph is typically set at 10 mm/mV. Time measurements and heart rate measurements are made horizontally on the electrocardiogram. For routine work, the paper recording speed is 25 mm/s.

7. The volume of blood outside the dialyzer is known as priming volume.
a) True
b) False
View Answer

Answer: b
Explanation: False, The volume of blood within the dialyzer is known as priming volume. It is desirable that this should be minimal. Priming volume of present day dialyzers ranges from 75 to 200 ml, depending on the membrane area geometry and operating conditions.
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8. The range of CMRR of Foetal electrocardiogram is ______________
a) 0-120 dB
b) 0-200 dB
c) 0-150 dB
d) 0- 130 dB
View Answer

Answer: a
Explanation: The range of CMRR of Foetal electrocardiogram is 0-120 dB. After proper placement of the electrodes, the signals are amplified in a preamplifier which provides a very high input impedance (100 MW) and a high sensitivity and good common mode rejection ratio (up to 120 dB). Abdominal FECG processing circuit is used for computing foetal heart rate.

9. Power Line Hum is responsible for most of common-mode interfering signal.
a) True
b) False
View Answer

Answer: a
Explanation: It is True. Power Line Hum is responsible for most of common-mode interfering signal. This is suppressed by a notch filter following the input amplifier. A sizable common-mode signal manages to pass through the input amplifier, a circumstance to be expected whenever electrodes spaced a few centimetres apart are attached to the human body in a hospital environment.
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10. What is the role of Cupraphan in haemodialysis?
a) used to check conductivity of dialyzer
b) used as membrane
c) used to check blood leakage
d) not at all used
View Answer

Answer: b
Explanation: Cupraphan is the commonly used membrane for haemodialysis. During haemodialysis, different substances of varying molecular weight are to be removed. It is a membrane consisting of natural cellulose and is considered puncture-proof, and of high tenacity and elasticity.

11. Which of the following is the property of instrumentational amplifier?
a) Extremely low input impedance
b) High bias and offset currents
c) Low slew rate
d) Very high CMRR
View Answer

Answer: d
Explanation: Instrumentational amplifiers have very high CMRR. Instrumentational amplifiers have extremely high input impedance. Instrumentational amplifiers have low bias and offset currents. Instrumentational amplifiers have high slew rate.

12. Foetal ECG signal detected via electrodes placed on mother’s abdomen is complex and requires attenuation of maternal signals for obtaining FHR.
a) True
b) False
View Answer

Answer: a
Explanation: It is True. Foetal ECG signal detected via electrodes placed on the mother’s abdomen is complex and requires attenuation of maternal signals for obtaining FHR. Also, due to the overlapping of the foetal ECG with the maternal ECG, about 20% to 50% of the expected pulses may be missing.

13. The blood is a good conductor of electricity.
a) True
b) False
View Answer

Answer: b
Explanation: It is False. The blood is not a good conductor of electricity. Blood is a poor conductor of electricity. This principle is used in Coulter counters to count the number of RBCs in the blood.

14. The range of FHR measurement due to substitution logic is between __________ bpm.
a) 20-220
b) 60-260
c) 40-240
d) 0-200
View Answer

Answer: c
Explanation: The range of FHR measurement due to substitution logic is between 40-240 bpm. The range of FHR measurement is limited to 40–240 bpm because of the substitution logic. Thereafter, the output of logic circuits go to standard heart rate computing circuits. The substitution logic requires a delay time to establish a missing foetal trigger pulse. It is thus kept as 270 ms.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter