What is the frequency cutoff for HiLo CE-Chirp®?

The HiLo CE-Chirp® is a stimulus which is used in automated ABR or ABRIS (auditory brainstem response infant screening).  Hearing screening programs typically recommend to screen hearing initially using a broadband stimulus such as a click or a CE-Chirp®. A problem with such stimuli is that although they are effective for eliciting an evoked response they are limited with respect to their frequency specificity. 

The HiLo CE-Chirp® provides clinicians with a more frequency specific stimulus which can be used in new born hearing screening. Its design is based on the CE-Chirp® which has a frequency range of 200 – 11,000 Hz. However the HiLo CE-Chirp® is actually two separate stimuli; a low frequency dominated stimulus and a high frequency dominated stimulus. 

The lower stimulus (Lo) covers the frequency range from 200 Hz - 1.5 kHz. Whereas the higher stimulus (Hi) covers the frequency range 1.5 kHz – 11,000 Hz.  In the software the screener will see two graphs which are generated for each ear. One for the Hi stimulus and one for the Lo. 

The above graph shows the display of the HiLo Stimulus in the Titan Suite. The Hi stimulus is shown in the column labelled high and the Lo stimulus is shown in the column labelled low. 

Typically when using the HiLo CE-Chirp® the Hi stimulus will pass quicker than the Lo because it less vulnerable to the effects of ambient noise.