Skip to main content

Audiometry- Hearing Testing

Hearing Loss is a common symptom. 

Once patients come with a history of hearing impairment, the simplest and most common hearing test that is carried out is the Pure Tone Audiogram (PTA). 

It is so-called because an instrument (Audiometer) is used to produce Pure Tones at different frequencies - these are then presented to the subject at different sound levels (Volume) and the patient's hearing is recorded.

TEST METHOD

The test is carried out in a soundproof chamber to elicit an accurate response.

It is preferably carried out in a two-room setting with the Tester and the Tested in a different room.

Two different responses are tested 

  •  Air Conduction - tested with Headphones
  • Bone Conduction- tested with a Bone Vibrator

The Bone Vibrator and the Headphones are snuggly fitted and the test is started by producing sound - usually starting at 1000 Hz at 25 dB. The tested is instructed to press a button when a sound is heard. 

The frequencies are then tested one by one and a graph is plotted - Frequency on the X-axis and Volume on the Y-axis.

TEST RESULTS

Test results are interpreted on two criteria

  • Type of hearing loss
  • Degree of hearing loss

Type of Hearing Loss

There are Three Types of hearing loss

  1. Conductive Deafness - caused by abnormalities of the External ear and Middle ear, including perforation of the eardrum and middle ear infections.
  2. Sensorineural Deafness - caused by abnormalities of the Inner Ear (Sensory) or the Acoustic nerve (Neural)
  3. Mixed Deafness- caused by a combination of the two- as when a middle ear infection leaks into the inner ear to cause damage to the Cochlear hair cells, etc.

Degree of Hearing Loss

Based on the Decibel level (Volume) at which sound is heard

  • < 15 dB                                 Normal hearing
  • 16-25 dB                               Minimal hearing loss
  • 26-40 dB                               Mild 
  • 41-55 dB                               Moderate
  • 56-70 dB                               Moderately Severe
  • 71-90 dB                               Severe
  • >90 dB                                  Profound

There are other tough to test situations where a battery of tests would be ordered. Examples of these are

- Auditory Processing disorder - in which case some other tests would be offered

- Non Organic Hearing Loss- Feigning hearing loss in the presence of normal hearing - as in malingering (for compensation, avoidance of duty, etc) or Functional hearing loss. There are some elaborate tests that can be carried out for detection.

CROSS HEARING AND MASKING

In the presence of Asymmetrical Hearing Loss sound given to one ear may cross over to the other ear (Non-Test Ear) - this is Cross Hearing.

To get an accurate reading in these instances the non-test ear is given a sound of the same frequency at a lower volume to prevent cross hearing- a process called Masking.

To summarize, a Pure Tone Audiogram is a reliable method to diagnose the type and degree of hearing loss a patient has.

It should preferably be done in a soundproof room by an experienced Audiologist.

Pic- Courtesy MedFirst ENT Centre

Comments

Post a Comment

Popular posts from this blog

Navigating Winter Health: A Comprehensive Guide for the Elderly

Image
As the winter season descends upon us, the risk of winter-related illnesses, especially among the elderly, becomes more pronounced. Understanding the causes and adopting preventive measures is crucial to ensure a healthy winter. The onset of winter often brings an increase in Upper Respiratory and Lower Respiratory tract infections, attributed to factors such as poor air quality, seasonal transitions, the emergence of winter viruses, and the chilling temperatures. The current scenario highlights a significant prevalence of these respiratory infections, with the elderly population, particularly those with underlying health conditions, such as diabetes, being more susceptible. Safeguarding against winter illnesses involves a combination of proactive steps: Vaccination: Ensure you have received your flu vaccine, providing added protection against prevalent winter viruses. Layered Clothing: Dressing warmly with layered clothing is essential. Pay attention to warm innerw
Read more

Turbinoplasty Surgery - explained by Dr. Rajesh Bhardwaj

Image
Turbinoplasty Surgery Turbinoplasty is a surgical procedure aimed at addressing nasal congestion and breathing difficulties caused by enlarged turbinates. The turbinates are bony structures covered in soft tissue located inside the nose, responsible for filtering, warming, and humidifying the air we breathe. When the turbinates become swollen due to allergies, chronic sinusitis, or other nasal conditions, it can lead to nasal obstruction and reduced airflow. Turbinoplasty involves the reduction or repositioning of the turbinates to improve nasal airflow and alleviate breathing problems. MedFirst ENT Centre, located in Delhi, India, offers top-quality turbinoplasty surgery performed by highly skilled ENT surgeon and their professional medical team. Turbinoplasty - Benefits and Risks Benefits of Turbinoplasty Surgery: Improved Breathing: Turbinoplasty can significantly enhance nasal airflow, leading to better breathing and reduced nasal congestion. Relief from Nasal Obstruction: Patients
Read more

Enlarged Adenoids

Image
Enlarged adenoids are common in children. The adenoids can become enlarged due to an infection or allergy. The adenoids are glands that sit behind the nose above the roof of the mouth. When they grow large, they can cause snoring and breathing problems. They also press upon the Eustachian Tube and cause middle ear problems. For more information please visit our blog ENT Doctor If you are looking for a Sr. ENT Specialist then please visit our Centre. Address - D 3/14, Vasant Vihar, Lane opposite, Vasant Vihar Club, Opp Shri Ram School, New Delhi, Delhi 110057. For an appointment - Please call at +919871150032.
Read more