Audiogram and Applications in Medicine

10 Questions

What does the lower curve of an audiogram indicate?

Faintest sound that can be heard

What is the purpose of using percussion in medicine?

To detect underlying structures by sound

What is the primary component of a stethoscope that acts as an impedance matcher?

Bell

On what factors does the natural frequency (F_res) of the stethoscope's bell depend?

Diameter and tension of the diaphragm

Which types of percussion sounds can be produced by striking the body surface?

Resonant, hyper-resonant, and dull

What is the function of the diaphragm in a stethoscope?

To resonate with the frequency of the body sounds

What does the upper curve on an audiogram represent?

Pain threshold

Which frequency range do heart sounds typically fall into?

Lower frequency range

What components are found in modern stethoscopes?

Bell, tubing, and earpieces

At what frequency is a sound barely audible according to the audiogram?

1000 Hz

Study Notes

Audiogram

An audiogram displays the faintest sounds that can be heard (hearing threshold) and the loudest sounds that can be heard without pain (pain threshold)
At 1000Hz, a sound is barely audible

Applications of Audible Sound in Medicine

Percussion

Percussion involves producing sounds by striking the body surface to detect underlying structures
There are three types of percussion sounds: resonant, hyper-resonant, and dull

Stethoscope

A stethoscope is a diagnostic instrument that amplifies sounds made by the body
Modern stethoscopes consist of a bell, tubing, and earpieces
The bell serves as an impedance matcher between the body and the air in the tube
The natural frequency of the bell (Fres) depends on the diameter (d) and tension (T) of the diaphragm: Fres ∝ √(T/d)
The appropriate bell size and diaphragm tension must be chosen to selectively pick up certain frequency ranges (e.g., low-frequency heart murmurs or high-frequency lung sounds)

Image Descriptions

Image 1: An audiogram showing the relationship between loudness in dB and frequency in Hz, with three regions: threshold of audibility, threshold of pain, and normal hearing range
Image 2: A diagram of a doctor using percussion to examine a patient
Image 3: A stethoscope diagram showing a bell, tubing, and earpieces, with the bell serving as an impedance matcher
Image 4: A graph showing the relationship between sound intensity (dB) and frequency (Hz), divided into heart sounds and lung sounds, with heart sounds typically lower in frequency than lung sounds