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Right option is (a) eustachian tube

Easiest explanation: The middle ear is exposed to atmospheric pressure only through the eustachian tube, which connects it to the pharynx and NOSE or MOUTH. The sound energy from the tympanic MEMBRANE is transmitted through the cavity of the middle ear, to the receptor cells in the inner ear, which are surrounded by fluid. The tympanic membrane SEPARATES the ear canal from the middle ear cavity.

Right option is (a) 300–3000 Hz

Easy 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.

The correct answer is (d) air-conduction and bone-conduction thresholds of hearing

The best EXPLANATION: A pure-tone AUDIOMETER is used PRIMARILY to obtain air-conduction and bone-conduction thresholds of hearing. Audiometers may be divided into two main groups on the BASIS of the TYPE of stimulus they provide to elicit an auditory response: pure-tone audiometers and speech audiometers. These thresholds are helpful in the diagnosis of hearing loss.

Right answer is (a) N = 10 log I1/I2

For explanation: If I1 and I2 are two intensities in watts per square centimetre, then the number of decibels with which they are related can be expressed as N = 10 log I1/I2. ATTENUATION is commonly expressed in negative dB numbers whereas amplification is given in POSITIVE dB numbers. Use of decibels as units for comparison of intensities help to avoid all mathematical calculations except algebraic addition or subtraction of small numbers. The transmission efficiency of any MEDIUM like air, a hearing aid or an AMPLIFIER is usually expressed in dB as a gain when the output is greater and as a loss, if LESS.

The correct answer is (a) True

For explanation I would say: It is FALSE. The hearing threshold is not an invariable FIXED intensity above which sound is always heard and below which sound is NEVER heard. In fact, the SENSITIVITY of the auditory mechanism is found to vary with interactions between certain physiological, psychological and physical factors. Therefore, the threshold may be regarded as an intensity range within which sound STIMULI at or near the statistically determined threshold may or may not be perceived.

Right answer is (d) notch filters

Best 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.

Right answer is (B) False

For EXPLANATION I would say: 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.

The CORRECT answer is (C) mm/mV

Best 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.

Right choice is (a) True

To elaborate: 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.

Correct CHOICE is (c) unit less

Best explanation: Since DB is merely a ratio, it is a dimensionless entity.Decibel expresses the logarithm of the ratio between two sound intensities, powers or sound pressures. Use of decibels as units for comparison of intensities help to avoid all mathematical calculations except ALGEBRAIC addition or subtraction of small numbers. The transmission efficiency of any medium like air, a HEARING aid or an amplifier is usually EXPRESSED in dB as a gain when the output is greater and as a loss, if less.

The correct option is (b) stapes

To elaborate: One of the BONES, called the stapes, rests upon the lower end of the cochlea and passes the vibrations directly into the FLUID within.A chain of THREE small, MIDDLE ear bones couple the tympanic membrane to a membrane COVERED opening, called the oval window. The total force on the oval window is the same as that on the tympanic membrane.

The CORRECT option is (d) Very high CMRR

The best 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.

Correct option is (a) 0-120 dB

The best I can explain: 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.

The correct choice is (C) 40-240

To explain I would say: 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.

Right choice is (a) True

For 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.

The correct choice is (b) False

The explanation is: 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.

Right answer is (c) –10 dB to +100 dB

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.

Correct answer is (d) audiometer

The best I can explain: An audiometer is specialized EQUIPMENT, which is used for the IDENTIFICATION of hearing the loss in individuals, and the quantitative DETERMINATION of the degree and nature of such a loss.Both frequency and output are adjustable over the audio range. The INSTRUMENT is also provided with a calibrated noise source and bone-conductor vibrator. It is essentially an oscillator driving a pair of headphones and is calibrated in terms of frequency and ACOUSTIC output.

Right answer is (b) WATT per sq. cm

For explanation: Sound INTENSITY MAY be defined as the amount of energy flow per unit time through a unit area PERPENDICULAR to the direction of energy flow. It is expressed as watts per square centimetre. However, the common receivers of sound are microphones, which do not measure sound intensity directly.

The correct ANSWER is (a) True

For explanation I would SAY: It is true. Air conduction, by DEFINITION, is the transmission of sound through the external and middle ear to the internal ear.Bone conduction, on the other hand, refers to the transmission of sound to the internal ear mediated by mechanical vibration of the cranial bones and soft tissues.Clinical observation has shown that hard-of-hearing PATIENTS with middle ear disease usually have normal hearing by bone conduction, whereas patients with INNER ear involvement have decreased or diminished bone-conduction.