How to perform the Alternate Binaural Loudness Balance (ABLB) test with Equinox Evo
Required equipment
- Equinox Evo
- Patient response button
- Headphones or insert phones
Test procedure
First, set up the protocol to do ABLB as this is not a separate test screen.
Go to Menu | Setup | AC440 setup.
Create new protocol.
Under Tone | Common, select ‘Reverse’ for channel 1 and ‘Alternate’ for channel 2. Click apply.
Figure 1: ABLB protocol setup.
Clarify the test procedure for the patient. Explain that they will now hear tones in both ears, which will be presented alternatively in each ear. The patient should then inform you when the two tones sound equal in intensity/loudness.
Perform the ABLB at frequencies where you assume recruitment. Set the intensity level on the impaired ear to 20 dB above the pure tone threshold using channel 2.
Present tones for both channels by holding in the tone switch for channel 1. Adjust the intensity level in the better ear until the perceived loudness is identical to the impaired ear using channel 1.
It is not possible to have any visible graphs shown on the audiogram. If written down on an audiogram, a laddergram will be made for interpretation.
ABLB results
The ABLB results are interpreted based on the laddergram, which displays the difference between the intensities for the right and left ear.
The good ear is used as a reference and displays the normal dynamic range where no recruitment is present. The poorer ear will display a narrowed dynamic range which indicates a degree of recruitment.
