Auditory Steady State Response (ASSR)
Auditory Steady-State Response (ASSR) is a quick and simple objective electrophysiological measure producing frequency-specific hearing thresholds in response to rapid auditory stimuli. It estimates the behavioral pure-tone audiogram from which questions regarding hearing, hearing loss, and aural rehabilitation can be answered. It is well-suited for testing infants, young children, and other individuals unable to provide reliable behavioural responses.
The steady-state pure tone signals(modulated in amplitude and frequency) are used in ASSR unlike, the transient signals of tone bursts or clicks used in ABR producing a frequency-specific audiogram.
Auditory stimulus is presented through either insert ear phones, headphones or through BC transducer if doing BC ASSR. An ASSR typically uses frequency specific stimuli which is usually 500, 1000, 2000 and 4000 Hz with the aim of creating an estimated audiogram. In other words, ASSR is used to perform threshold estimation objectively.
Unlike auditory brainstem response which measures amplitude and latency of the response in the time domain, ASSR measures amplitudes and phases in the frequency domain. Another major difference is that in ABR it is only possible to test one frequency in one ear at a time in frequency-specific threshold ABR. ASSR allows for binaural testing; four frequencies in each ear at the same time. Which saves time and gives us more accurate information.
- Hearing loss of more than 80 dB can be detected. It can help in the early detection of the children who need cochlear implantation.
- ASSR can be done in all ages, any mental state, any degree of hearing loss.
- Multiple frequencies can be assessed at the same time, as long as their carrier frequencies utilize different modulation rates.
- ASSR is an objective test that can be analysed and interpreted easily using statistical methods.
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Dr. Rahul Kumar Bagla
MS & Fellow Rhinoplasty & Facial Plastic Surgery.
Associate Professor & Head
GIMS, Greater Noida, India
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