Auditory Steady-State Responses (ASSR), known in Spanish as Potenciales Evocados Auditivos de Estado Estable (PEAee), are one of the most recent objective methods for evaluating hearing.
ASSRs are brain responses obtained through repetitive acoustic stimulation. They are called “steady-state” because the response is maintained for as long as the stimulus is present. This technique differs from the widely used Brainstem Auditory Evoked Potentials (BAEP or ABR) in that it can determine auditory thresholds across a wider range and specifically by frequency.
ASSRs are not exactly a hearing test in themselves, but they make it possible to identify and quantify hearing loss in children and adults who cannot or do not wish to participate in a subjective test such as audiometry.
The patient’s direct collaboration is not necessary, but they must be calm and relaxed, and may even be asleep or sedated. The test does not involve any kind of risk.
To deliver the stimulus, we use insert earphones with disposable tips adapted to the patient’s age and the size of their ear canal. They are comfortable and minimize artifacts and background noise. Repetitive multi-frequency tonal acoustic stimuli modulated in amplitude are used—that is, sounds of different frequencies that vary in intensity.
To record the potentials produced in response to these stimuli, we use disposable self-adhesive electrodes of a size appropriate for the patient’s age. The response to the stimulus occurs when the threshold of the cochlear hair cells is reached in the region corresponding to the frequency of each tone. The resulting response is a quasi-sinusoidal wave whose frequency is exactly the same as the modulation frequency of the stimulus. Therefore, it can be distinguished from other frequencies and from the rest of the brain’s electrical activity.
This response is automatically analyzed statistically and displayed on a graph very similar to a pure-tone audiogram.
Advantages of Auditory Steady-State Responses (ASSR)
ASSRs offer several advantages compared with other electroaudiometric techniques:
- They allow the use of acoustic stimuli similar to those used in conventional audiometry.
- They enable the simultaneous evaluation of several audiometric frequencies and even both ears at the same time, which reduces test duration.
- It is a doubly objective technique, as it is not affected by the subjectivity of the person being tested or by the examiner’s subjectivity when interpreting the response, thanks to the automatic detection using statistical indicators.
The main clinical application of ASSR is determining auditory thresholds. The audiograms obtained with this technique allow us to establish the threshold for each frequency with a small margin of error, which is especially useful for:
- Determining hearing levels in young children who have not passed neonatal hearing screening or who were not screened and are still unable to undergo pure-tone audiometry. Results obtained with ASSR allow us to determine the child’s threshold more reliably than with brainstem auditory evoked potentials (ABR/BAEP), and therefore to decide the appropriate course of action with less margin of error (discharge, follow-up, hearing aid, cochlear implant, etc.).
- Determining hearing levels in uncooperative children or adults, whether due to intellectual disability or in cases of simulation for various reasons.
If you wish to undergo this test, you may contact us to schedule it at our otolaryngology clinic.
If you would like to undergo this test, you may contact us to schedule it at our otolaryngology clinic.