Impedance is a measure of the opposition to the flow of energy through a medium. It is a complex number that has both magnitude and phase. The magnitude of the impedance is called the admittance.
What is acoustic impedance in audiology?
Acoustic impedance is the impedance of sound waves traveling through the ear. It is determined by the properties of the ear canal, eardrum, middle ear ossicles, and cochlea.
What is impedance audiometry used for?
Impedance audiometry is a type of hearing test that measures the acoustic impedance of the ear. It is used to diagnose a variety of ear conditions, such as:
- Ear infections
- Middle ear effusions
- Acoustic neuromas
What is the difference between admittance and impedance audiometry?
Admittance audiometry is a type of hearing test that measures the admittance of the ear. Admittance is the reciprocal of impedance. In other words, admittance is a measure of how easy it is for sound to flow through the ear, while impedance is a measure of how difficult it is for sound to flow through the ear.
How is impedance audiometry performed?
Impedance audiometry is performed using an immittance meter. An immittance meter is a device that measures the acoustic impedance of the ear. The immittance meter has a probe that is inserted into the ear canal. The probe has a speaker and a microphone. The speaker produces a sound at a specific frequency, and the microphone measures the sound pressure in the ear canal.
What does a normal impedance audiogram look like?
A normal impedance audiogram shows a peak in the admittance curve at around 220 Hz. This peak is caused by the compliance of the middle ear. The admittance curve should be symmetrical on both sides.
What does an abnormal impedance audiogram look like?
An abnormal impedance audiogram can show a variety of patterns, depending on the underlying ear condition. Some common abnormal patterns include:
- A flat admittance curve: This can be caused by a middle ear effusion or otosclerosis.
- A decreased peak in the admittance curve: This can be caused by a perforation in the eardrum.
- A peak in the admittance curve at a different frequency than 220 Hz: This can be caused by a problem with the ossicles.
Why is impedance audiometry important?
Impedance audiometry is an important tool for diagnosing ear conditions. It is also used to monitor the progression of ear conditions and to evaluate the effectiveness of treatment.
If you are concerned about your hearing, it is important to see an audiologist for a hearing test. An audiologist can perform impedance audiometry and other hearing tests to diagnose any ear conditions that you may have.