Alternate binaural loudness balancing plots recruitment as non-parallel laddergram rungs

Evidence

The ABLB is very straightforward — a tone is presented at a specific dB HL to the patient’s healthy ear. The audiologist presents a tone at the same frequency to the patient’s impaired ear. The tones are always presented sequentially (e.g., alternating). In one approach, the patient hears the reference tone in this good ear and tells the audiologist to increase or decrease the level of the sound in his impaired ear until it is equally loud to the tone in his healthy ear. Another approach is to present the fixed tone to the impaired ear. Whatever the approach, the audiologist repeats the measurement at another level (usually in 10 or 20 dB steps, depending on the degree of hearing loss). The audiologist then plots a laddergram, in which one rung of the ladder plots the dB HL levels in the healthy ear and the other rung of the ladder shows the loudness-matched levels (in dB HL) in the impaired ear. Figure 8–1 illustrates that a laddergram from a patient with recruitment in the right ear will show non-parallel rungs (loudness will grow faster in the impaired ear than in the healthy one; see the right panel of Figure 8–1). An ear that does not exhibit recruitment will show parallel rungs (see the left panel of Figure 8–1). This type of laddergram might be indicative of retrocochlear pathology. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1752

Categorization

• DEFINE: Explains the ABLB method and laddergram reading, core to understanding how recruitment is clinically measured.