Influence of Pump Speed and Pressure Sweep Direction on Wideband Absorbance in Clinically Normal Hearing Individuals

Abstract

Aim and Objectives: The present study aimed to investigate the influence of procedural variables—namely pump speed and pressure sweep direction—on wideband absorbance (WBA) in ears with clinically normal hearing sensitivity. Specifically, the study examined how different pump speeds (very slow, slow, and medium) and pressure sweep directions (ascending and descending) affect WBA across a wide frequency range under tympanometric peak pressure (TPP) and ambient pressure conditions. Additionally, it explored how these variables interact with different tympanogram types (A, As, and Ad). Methods: Eighty-eight ears from adults aged 18–45 years with normal hearing and no otological complaints were classified into three groups based on tympanogram type: A, As, and Ad. Wideband absorbance (WBA) was measured using the Interacoustics Titan IMP440/WBT440 across 16 frequencies (226–8000 Hz) under tympanometric peak pressure (TPP) and ambient pressure. Measurements were conducted at three pump speeds (50, 100, and 200 daPa/s) and in ascending and descending pressure sweep directions. Repeated measures ANOVA assessed the main and interaction effects of test conditions and tympanogram type on absorbance. Results and Discussion: Absorbance values at TPP were consistently higher than at ambient pressure, especially at lower frequencies (250–1000 Hz), across all pump speeds. Although pump speed alone had minimal effect on WBA, significant interaction effects were found with tympanogram type—particularly in Ad-type ears—at mid and high frequencies. The direction of the pressure sweep had a notable impact on absorbance levels, with descending sweeps producing higher wideband absorbance (WBA) compared to ascending sweeps, especially in the higher frequency range (4000–6000 Hz). Additionally, the combined effect of pump speed and sweep direction exhibited distinct variations across different tympanogram types. Ad-type ears showed elevated absorbance during descending sweeps at medium speeds, while As-type ears displayed more stable absorbance with slower ascending sweeps. These findings highlight the role of tympanometric compliance and procedural variables in shaping WBA outcomes. Conclusion: The study emphasizes the importance of standardizing procedural parameters in wideband tympanometry, especially when evaluating ears with non-Type A tympanograms. Measuring WBA at TPP using descending sweeps and optimized pump speeds may enhance diagnostic accuracy and clinical reliability.