What is an Audiogram and what information does it provide us with (Audiogram Analysis)?

First, before we explain the audiogram, it is necessary to familiarize ourselves with the process of performing audiometry. Pure tone audiometry, also called pure tone audiometry, is one of the most basic and fundamental diagnostic tests.

In this test, the test subject is placed in an acoustic chamber and a headphone or bone vibrator is placed on the ear or behind the earlobe and on the mastoid bone. Then, the audiologist presents sounds at different frequencies and intensities to the test subject’s ears through a device called an audiometer. When the test subject hears each tone, he or she must respond, often by pressing a button. This response (pressing a button or raising a hand) indicates that the sound has been heard. (Link for more information)

The pure tones evaluated in audiometry include frequencies of 250, 500, 1000, 2000, 4000, and 8000 Hz, which are sounds similar to a car horn or whistle. Based on the responses received from the test subject to the presented sounds, the audiologist changes the intensity of the sound, increasing or decreasing it, in order to determine the weakest intensity that the test subject can hear at each frequency.

Hearing Threshold

The weakest sound that the test subject can hear at any frequency is called the hearing threshold.
As you know, the unit of measurement for sound is decibels (dB), so hearing thresholds are also measured and recorded in terms of dB HL.

Hearing loss diagnosis is fundamentally based on measuring a patient’s hearing thresholds across a range of frequencies, which creates their unique audiogram. This diagnostic profile precisely quantifies the degree and type of hearing impairment. The resulting audiogram data is then the essential blueprint for a successful hearing aid fitting. Consequently, an accurate diagnosis directly informs the programming and customization of the hearing aids, ensuring the amplification targets the individual’s specific auditory gaps.

What is an Audiogram?

The hearing thresholds obtained in the audiometric test are recorded separately for each ear in the form of a graph on a sheet of paper and are called audiograms or ear tapes. The thresholds of the left ear are displayed as blue symbols and the thresholds of the right ear are displayed as red symbols. The audiogram consists of two horizontal and vertical axes. The horizontal axis shows frequencies and the vertical axis shows sound intensity.

If the hearing thresholds obtained at all frequencies are within the range of 0-15 dB HL, the individual’s hearing status is normal, and if it exceeds 15 dB HL, the individual enters the hearing loss range and is divided into different degrees based on how far away from the normal range it is.

As mentioned, pure tones are presented to the test subject’s ears in two ways:
1) Through headphones, in which case the thresholds obtained are called airway thresholds
2) Through a bone vibrator, in which case the thresholds obtained are called bone conduction thresholds.

An audiogram is the essential tool for mapping a hearing loss diagnosis. Precise audiogram interpretation begins by analyzing how the air and bone conduction thresholds shift away from the normal range. This audiogram analysis, known as audiogram interpretation, directly reveals which part of the ear is damaged, as well as the extent of that damage. Ultimately, this critical analysis informs the fitting of hearing aids, as the specific hearing loss pattern dictates the exact programming and approach needed. For a detailed breakdown of what different threshold patterns mean, the specific mechanics are explained in the section on types of hearing loss.

Degree of hearing loss

Depending on how far the hearing thresholds recorded in the audiogram are from the normal range (15 dB HL), the degree of hearing loss is classified as follows:
(Usually, in determining the degree of hearing loss, the average of three frequencies of 500, 1000, and 2000 Hz is considered.
Α) 0-15 dB HL (Normal hearing status)
Β) 15-25 dB HL (light hearing loss)
Γ) 25-40 dB HL (Mild hearing loss)
Δ) 40-55 dB HL (Moderate hearing loss)
Ε) 55-70 dB HL (Severe hearing loss)
Ϝ) 70-90 dB HL (Severe to profound hearing loss)
Ζ)  >90 dB HL(Profound hearing loss)
Η) Hearing loss