The purpose of calibration is to measure potential feedback paths in order to set a starting point for dynamic adaptation in response to feedback conditions. The Feedback Manager is active in 16 bands, each of 500Hz width, irrespective of the technology level; for instance, it will be active in 16 bands even for a six channel instrument.
Always initialize the feedback manager for new fittings, or when the wearer reports feedback artefacts, or if there have been changes to potential feedback pathways (for example, if changing RIC dome type or size).
Re-calibrating the feedback manager is also recommended when re-fitting an aid following a repair; this is particularly important for fittings with significant feedback potential. Our Repair Team have also observed that some aids with reported “Internal Feedback” have simply not had the feedback manager initialized.
It is important that initialization is conducted in a quiet environment, with the aid correctly inserted into the ear. Counsel the wearer to expect noise that could be quite loud and ask that they remain quiet and not speak during the test (“Oh, yes I can hear that easily” is a comment we’re probably all familiar with in the middle of a feedback test). Excessive environmental noise may lead to an inaccurate result or even prevent successful initialization.
Following initialization, the following status messages are possible:
It is important to note that after successful initialization, if a gain adjustment is recommended, the Auto Gain Adjust Button will be active and will be highlighted with a yellow warning triangle. The “Gain Margin” graph will show any frequencies with potential feedback (as illustrated below); those frequencies with results above the horizontal axis have the potential for feedback and will be highlighted in gold.
Note that the results are shown separately for each program and for both omni and directional modes (if applicable).
Once the feedback manager has been successfully initialized the following options are available:
Quick Quiz (Answers later):
1: Which feedback cancellation strategy is best for music?
2: Which strategy might be an acceptable alternative?
A. Adaptive, High Sensitivity
B. Adaptive, Low Sensitivity
As a troubleshooting tool, the Inspire Speech Mapping feature can be used to identify frequencies at which feedback may be present. Start Speech Mapping (from either the QuickFit screen or from the blue Navigation bar to the left of the main window), and in a quiet environment, look for any peaks in the histogram. Cover the ear, move the pinna or ask the wearer to make a chewing motion to confirm a suspected issue. The graph below shows a simulated feedback peak.
1: D – Static. To maintain the purity of musical notes, use of the static mode will prevent any possible artefacts from the anti-feedback algorithm attempting to cancel perceived feedback, which is in fact a feature of the tonal characteristics of the music.
2: B - Adaptive, Low Sensitivity This is a valid alternative to D where the hearing loss dictates some degree of feedback cancelation, even with a dedicated music listening program.
For serious music lovers, sound engineers or professional musicians, reducing or turning off noise reduction features and reducing compression can also be beneficial to keep the sound as natural as possible.
Bruce Brown - Product & Technical Support Specialist
Bruce brings 30 years’ experience in the electronics industry, most recently in the hearing aid sector. Bruce’s background includes a BSc in Applied Physics and a Master’s Degree in Information Systems. The first half of his career was devoted to engineering and product management roles within integrated circuit manufacturers in the UK and The Netherlands. Bruce also spent a year in California’s Silicon Valley, learning the latest manufacturing techniques.
In 2000, Bruce moved into the hearing aid industry, joining a major European manufacturer of hearing aids. Initially working on the development and introduction of new hearing aid fitting software, his role quickly expanded into technical support for hearing aid fitting, audiological equipment and practice management software. He later became the manufacturer’s Key Account Manager for a major UK optical chain at the time of their entry into the private hearing aid market. Bruce also qualified as the UK equivalent of an audiometrist, and ran his own business before joining Starkey in 2014.