Beltone Adaptive Fitting Algorithm (BAFA)
Beltone SOLUS PRO and Beltone SOLUS use BAFA, Beltone’s proprietary fitting algorithm, for setting target gains and frequency response recommendations. Other target rules such as DSL I/O and NAL R/P can also be selected.
To initially fit the client with gain settings that optimally approximate final use settings has long been the ultimate goal of hearing aid prescription fitting formulas. The four key areas that are addressed in this process are:
- To make speech audible
- To increase speech intelligibility
- To provide a range of loudness
- To keep sounds below the patient’s discomfort level.
In some cases, these statements are, unfortunately, somewhat mutually exclusive in practice. For example: Which is more important: normalizing loudness, equalizing loudness, or maximizing intelligibility? To a hearing impaired individual, all are important.
Mapping the dynamic range
BAFA seeks to optimize the different aspects of ideal fitting and has proven itself to be an effective starting point for fitting all hearing instrument styles and circuits. What BAFA provides is shown in this Mapping of Audiological Inputs to the Reduced Dynamic Range, where the proportions between the normal dynamic range and the hearing impaired dynamic range are sought to be maintained:.
The resulting target curves will demonstrate that:
- For mild losses, the gain differences between soft and average sounds will be greater than the gain differences between average and loud sounds
- For moderate losses, the three gain curves will be equally distributed, i.e., approximately the same amount of gain difference will be provided between the average and soft or loud inputs
- For severe losses, the gain differences between the soft and average sounds are smaller than the gain differences between the average and loud sounds.
The goal for Beltone remains to initially fit the patient with gain (and other) settings that optimally approximate final use settings, while appreciating the inherent unpredictability of personal preference in judging satisfactory hearing instrument gain.