What is the Alternate Binaural Loudness Balance test?
The Alternate Binaural Loudness Balance (ABLB) test is a diagnostic tool used to assess subjects with unilateral hearing loss. It’s a subjective test that relies on the patient's ability to compare the loudness of sounds presented to each ear to indicate where they are equal. It is commonly used to identify recruitment/hyperacusis in the poorer ear of asymmetrical hearing losses.1
What's involved in an ABLB test?
During the ABLB test, the patient wears headphones that present different intensity tones to each ear. They are then asked to adjust the volume of the tone in the test ear until it matches the volume of the tone in the reference ear.
The intensity is fixed in the reference (less-impaired) ear (initially beginning at 20dB above the pure tone threshold). This process is repeated several times at different intensities and frequencies to obtain a comprehensive assessment of the patient's hearing ability and to identify recruitment in the impaired ear.
Why perform an ABLB test?
The ABLB test is useful in diagnosing recruitment or reduced dynamic range in asymmetrical hearing losses. Overall, the ABLB test is a valuable tool in diagnosing hearing issues, and it can provide critical information that can aid in developing an effective treatment plan.
However, it should be used in conjunction with other diagnostic tests and assessments to obtain a complete picture of the patient's condition.
How to perform an ABLB test
Here are the basic steps involved in conducting an ABLB test:
- Explain the procedure to the patient: before starting the test, ensure the patient understands what’s expected of them.
- Position the patient: the patient should be seated comfortably in an audiology booth or soundproof room, wearing headphones that are connected to the audiometer.
- Present the tones: the audiologist will present different tones to each ear at varying frequencies, starting at a low volume and gradually increasing intensity until the patient can hear the tone clearly. The reference for the better ear stimulus should initially be set to 20dB above the threshold level.
- Adjust the volume: the patient is asked to adjust the volume of the tone in one ear (increased or decreased) until it matches the volume of the tone in the reference ear. The process is repeated several times at different frequencies (5dB increments) to obtain a comprehensive assessment of the patient's hearing ability – this can be plotted on a laddergram to display and compare the intensity levels that result in equivalent loudness between both ears.
- Record the results: the audiologist records the patient's responses to each tone and frequency (in 10 dB SL increments) and uses this information to evaluate their hearing ability and identify any asymmetrical hearing loss or balance issues.
It's important to note that the ABLB test should be performed by a trained audiologist or hearing healthcare professional using calibrated equipment to ensure accurate results. It should also be used in conjunction with other diagnostic tests and assessments to obtain a complete picture of the patient's hearing and balance health.
ABLB test results
The ABLB results are interpreted based on a laddergram, which displays the difference between the intensities for the right and left ear. The good ear is used as reference and displays the normal dynamic range where no recruitment is present.
A positive indication of recruitment is when equal loudness is perceived with a reduced dynamic range in the poorer ear. For example, when a smaller increment is added in relation to the threshold, such as 20 dB above the better ear, the threshold is perceived to be equally as loud as 10 dB above the poorer ear threshold.
A negative indication of recruitment is when the dynamic range of both the poorer and better ear is equal. For example, equal increments of stimulus above threshold (20db) are perceived to be equally as loud.
We offer a range of diagnostic audiometers with special test functionality:
The Model 260 is a cost-effective and portable diagnostic audiometer. With no configuration or set-up required and an intuitive design, this model requires minimal training.
The Model 270 is a two-channel diagnostic audiometer which provides an extensive range of measurements for diagnostic audiology and hearing aid fitting quickly and efficiently.
The Model 270+ is a powerful two-channel diagnostic audiometer with enhanced technology for a more accurate and efficient testing experience.
For more information on our range of diagnostic audiometers, please visit our audiometers webpage, contact our customer support team on +44 (0)1865 880 846 or email us.
1Stach A.A., 1998. Clinical Audiology: An Introduction. Cengage Learning