Authors: Thomas Schwarz¹; Lena Schell-Majoor¹; Birger Kollmeier¹
¹Carl von Ossietzky Universität Oldenburg
Background: The “Adaptive Categorical Loudness Scaling” (ACALOS) is an established method in audiology to characterize suprathreshold hearing abilities individually, e.g., the residual dynamic range or recruitment effect. Its application for remote testing in audiology with uncalibrated hardware appears attractive, especially if the absolute hearing threshold and a calibration factor can be determined with the same test procedure by employing additional stimulus presentations near the estimated threshold level (“reinforced” ACALOS (rACALOS, Xu et al., 2025)). However, technical limitations of the mobile hardware leading to dynamic range restrictions (nonlinear sound processing, automatic gain control, clipping) may limit the applicability of the method which motivates this study.
Method: This pilot study investigates the impact of different hardware combinations on individual rACALOS data and derived loudness functions when using the Virtual Hearing Clinic (VHC), a modular remote testing platform. Five normal-hearing participants performed monaural tests with a 4 kHz narrow-band-noise stimulus in the lab. Four headphone models (Bluetooth in-ear, wired circumaural headphones) and two playback devices (smartphone, laptop) were combined into eight hardware configurations.
Results: For each hardware configuration, individual loudness functions and threshold estimates are obtained and the intra- and interindividual variance for normal hearing listeners is analyzed and compared to normal hearing reference data.
Conclusion: The magnitude of variance introduced by the use of different hardware significantly affects the feasibility of rACALOS in remote testing. The results will enable an estimation of expected accuracy and reliability for loudness scaling data obtained with the VHC.
