Audiogram and Applications in Medicine

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

This quiz covers the concept of an audiogram, including the hearing threshold and pain threshold, as well as the applications of audible sound in medicine, such as percussion.