Which tympanogram type suggests middle ear involvement from the presence of fluid, with no identifiable peak and normal ear canal volume?

Which tympanogram type suggests middle ear involvement from the presence of fluid, with no identifiable peak and normal ear canal volume?

• A. Type AS
• B. Type B
• C. Type A
• D. Type AD

Answer: (A)

The key idea is how tympanometry reflects middle ear status by showing how the eardrum moves across pressure changes. A fluid-filled middle ear dampens that movement so the trace does not form a peak at any pressure; you get a flat tracing. If the ear canal volume is normal, it means the eardrum isn’t perforated and there isn’t a large opening to the outside, so the flat pattern is due to fluid in the middle ear rather than a perforation or probe misplacement. So, a flat tympanogram with no identifiable peak and a normal ear canal volume points to middle ear effusion (fluid in the middle ear). By contrast, normal peak patterns with normal pressure (Type A) show normal tympanic membrane movement, a shallow peak (Type AS) indicates reduced mobility, and a high peak (Type AD) indicates hypermobility. A truly flat curve with a very large ear canal volume would suggest perforation or a tube, not fluid.

The key idea is how tympanometry reflects middle ear status by showing how the eardrum moves across pressure changes. A fluid-filled middle ear dampens that movement so the trace does not form a peak at any pressure; you get a flat tracing. If the ear canal volume is normal, it means the eardrum isn’t perforated and there isn’t a large opening to the outside, so the flat pattern is due to fluid in the middle ear rather than a perforation or probe misplacement.

So, a flat tympanogram with no identifiable peak and a normal ear canal volume points to middle ear effusion (fluid in the middle ear). By contrast, normal peak patterns with normal pressure (Type A) show normal tympanic membrane movement, a shallow peak (Type AS) indicates reduced mobility, and a high peak (Type AD) indicates hypermobility. A truly flat curve with a very large ear canal volume would suggest perforation or a tube, not fluid.