Acoustic Transparency in Hearables—Perceptual Sound Quality Evaluations

In hearing devices, hear-through features that aim to provide the user with acoustic awareness of their surroundings are becoming increasingly popular. In particular, awareness of the user's surroundings can be achieved when the open ear properties can be perceptually restored with the device inserted, typically called acoustic transparency. In this study, we investigate the perceptual sound quality of six commercial consumer hearing devices and two research hearing devices with hear-through features. We conducted two experiments in which normal-hearing participants rated the perceptual sound quality of different audio signals processed by the hearing devices. In Experiment 1, the participants were not provided with an explicit open-ear reference, while in Experiment 2, the open-ear reference was explicitly provided. Results show that most commercial consumer hearing devices are not able to achieve a perceptual sound quality comparable to the open ear. Furthermore, results indicate that a main contributing factor to the overall quality of a hear-through feature is determined by the similarly of the transfer function with the device inserted and the open ear transfer function.