Sound audiometry & speech audiometry

An audiogram is a graphical representation of a person's hearing ability, which is determined by the results of the audiometry test. During the test, the patient's hearing threshold is established, which is the minimum intensity at which they can perceive auditory stimuli in different frequency ranges.

Some advanced applications use the Doppler effect to understand how blood flow works in the inner ear and how it affects hearing. 

The audiogram is created using standard forms that record various frequencies, or pitches, and their respective intensities, measured in decibels. A measurement of zero on the chart indicates normal hearing.

The audiogram includes two values that describe the two ways in which sound can enter the inner ear. The first value refers to air conduction, the most common method of hearing, in which sound waves travel from the outer ear to the inner ear. The second value refers to bone conduction, in which sound vibrations reach the inner ear through the bones of the skull.

The aim of speech audiometry is to assess the patient's ability to comprehend speech spoken at a specific volume. This non-invasive hearing test is suitable for individuals of all age groups, including children and the elderly.

A speech audiometry is done as follows: 

• The hearing test is conducted in a soundproof booth and takes roughly 15 minutes. 
• The patient wears headphones through which words spoken at varying volumes are presented.
• The patient t is then required to repeat the words back to the doctor or audiometrist.
• The outcomes of the test are shown on a graph, known as a speech audiogram.

Are you interested in learning how to correctly read and interpret a speech audiogram? The speech audiogram is evaluated in a similar manner to the sound audiogram, with the examiner recording the percentage of correct responses provided by the individual during the hearing test. The speech audiogram is categorized into three different comprehension thresholds.

• Threshold 1 represents a comprehension rate of 0%, meaning that the spoken word is perceived as an indistinguishable noise. 
• Threshold 2 corresponds to a comprehension rate of 50%. 
• Threshold 3 symbolises a high level of comprehension, in which speech messages are fully understood at 100%.

In the speech audiogram, these three comprehension thresholds are connected by the auditory threshold curve, an S-shaped curve that indicates a person with normal hearing in the speech audiogram. Responses are assessed by determining how far the hearing threshold deviates from the 100% threshold.