A doctor listens to a patient's chest using the stethoscope in Fig. 1. The chest piece is placed on the skin and is joined to the doctor's earpieces by two ...
Question 1 Report
A doctor listens to a patient's chest using the stethoscope in Fig. 1. The chest piece is placed on the skin and is joined to the doctor's earpieces by two flexible tubes. The doctor compares the sound of breathing at several points. The chest piece is pressed gently so that it makes good contact with the skin. Sound vibrations from the chest cause the diaphragm in the chest piece to vibrate. The enclosed air in each tube carries the sound towards the doctor's ears. The diagram shows a simplified route of the sound.
(a) What vibrates first in the chest piece when it is placed on the patient? [1]
(b) Describe how sound travels through the air in a tube. [2]
(c) Explain why good contact between the chest piece and skin is important. [2]
Fig. 1 shows an audiology technician testing a musician's hearing with headphones. A pure tone is played first at 1000 Hz and then at 8000 Hz. For each frequency, the technician reduces the sound level until the musician can just hear it. The room has padded walls to reduce reflected sound. The technician asks the musician to press a button whenever a tone is heard. The result is used to advise the musician about protecting their ears during amplified performances. The diagram shows the ear and the route followed by a sound wave.
(a) Name the structure that vibrates when sound reaches the end of the ear canal. [1]
(b) What does a result at 8000 Hz test? [1]
(c) Explain why padded walls improve this hearing test. [2]
(d) Give one way the musician can reduce the risk of hearing damage. [1]
Answer Details
Stethoscope
(a) The diaphragm of the chest piece vibrates first when the chest piece is on the patient. [1]
(b) Air particles vibrate back and forth. [1] This produces travelling compressions and rarefactions along the tube. [1] The disturbance travels to the earpieces, but the individual air particles only oscillate about their positions.
(c) Good contact reduces any air gap between the skin and chest piece. [1] This allows more vibration, and therefore more sound energy, to be transferred into the diaphragm. [1]
Hearing test
(a) The structure at the end of the ear canal that vibrates is the eardrum. [1]
(b) A result at 8000 Hz tests hearing sensitivity to a high-frequency, high-pitched sound. [1]
(c) The padded walls absorb sound and reduce reflections. [1] Consequently, echoes and background sound are less likely to affect whether the musician hears the test tone. [1]
(d) The musician can wear ear defenders to reduce the risk of hearing damage. [1] Reducing volume, taking breaks from loud sound, or moving farther from loudspeakers are also accepted.
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