According to a recent survey performed by MarkeTrak (2020), there is a clear consensus that current directional technologies in hearing aids are associated with higher user satisfaction. Considering that listening in noise remains one of the most important factors in purchasing a hearing device, the fact that directional technology is known to be the biggest contributor to the improvement of speech perception in noise (Appleton, 2014; Beck & Schum, 2005; Ricketts & Dittberner, 2002; Ricketts & Henry, 2002) underscores the need to ensure that hearing aid manufacturers provide the necessary fine-tuning options for the hearing care professional (HCP), including different directionality settings.
Different situations involve different listening goals.
Directional microphone technology has advanced to the degree that it has moved beyond the physical components to include more digital systems, which involve carefully designed algorithms and automatic steering that allow it to adapt effectively to changing listening environments. Different situations involve different listening goals. For example, the client needs a different listening strategy when taking a morning walk in the park versus when talking to friends in a restaurant. In the first case, localization and good sound fidelity are more likely to be given importance. Imagine that you are on the sidewalk: as you walk, a car turns at a corner and suddenly appears from behind, or an elderly neighbor might call out and try to catch your attention from a distance. As you go on your walk, you might want to appreciate the subtle twittering of the birds and the soft breeze rustling the leaves on the trees. In contrast, when you are trying to have a conversation with friends in a restaurant, understanding clear speech is given more importance. In addition to multiple speakers trying to get your attention, other competing background noise such as the ambient chatter and music are surrounding you at the same time, making focusing on what you want to listen to a challenge. For the second case, getting a better signal-to-noise ratio is thus given more priority. To achieve different listening needs and goals, we need to make sure that hearing aid features such as directionality are able to support almost any given situation and match the listening goal of the user.
Different directionality options
Users also prefer different directionality options depending on the situation. In a quiet environment, it has been shown that clients generally prefer to have an omnidirectional mode to maintain a natural listening experience with good sound quality (Walden, 2007; Humes, 2018). In noisier environments, this preference changes to a more directional mode (Preves et al, 1999) with additional directional technologies such as adopting different polar responses in different frequency regions (Beck & Schum, 2005) and binaural beamforming techniques to further refine the ability to hear in noisy environments (Appleton, 2014). But despite how far directional technology has come, there are still challenges when it comes to having the appropriate directionality mode for different listening situations.
Bernafon introduces 4 directionality modes
With those challenges in mind, Bernafon introduces four directionality modes under Hybrid Noise Management™ in Oasisnxt which adapts the best of what current directional technology has to offer in the latest product from Bernafon – Alpha. This includes Dynamic, Adaptive Full Directionality, Fixed Omni, and Fixed Directionality.
Here is an overview to get the maximum benefit out of each directionality mode by utilizing it for the right situation:
||Adaptive Full Directionality
|How it works
||Continuously steers the response from omnidirectional (quieter environment) to a more directional pattern (noisier environment) by adjusting the polar pattern in each of the 24 frequency bands with null steering for maximum noise attenuation
||Fades between a series of predetermined traditional directional patterns (cardioid to hypercardioid) depending on the amount of noise
||Provides a fixed, omnidirectional response from all directions, including behind the client
||Provides a fixed, directional response across the entire frequency range. Here, the microphone is the most sensitive to signals from the front and less from the sides and behind the user (hypercardioid response).
|Fixed/Adaptive polar response
||Changes based on the detected sound environment
||Changes based on the detected sound environment
|Adapts to changing acoustic environments
|Coordinates and works together with the following features
Smart Noise Reduction
||For constantly fluctuating acoustic environments from quiet to noisy. Ensures the best directional response in almost any given environment with the goal to improve speech intelligibility in noise, especially with moving noise sources.
||For progressively noisier environments. This mode fades into increasingly directional polar patterns as the noise increases.
||For more quiet environments with little to no background noise, as when listening to the television, music, speech in reverberant environments and speech at a distance
||For environments with constant noise across all frequencies, with the desired speech source and background noise coming from opposite directions
Table 1: Overview directionality mode
True Directionality Plus option in Bernafon Alpha
It is a known fact that users on average wear their hearing aids more often in relatively quiet environments than in more complex listening environments (Humes, 2018). Therefore, it is just as important to prioritize the listening experience in simple environments just as in noisy environments. That is where the new True Directionality Plus option in Bernafon Alpha comes in. It enhances the sound quality by preserving the spatial cues as much as possible so that users can segregate sounds in the environment as well as tell where sound sources are both in terms of direction and distance. True Directionality Plus is based on measurements from real ears which allows it to create a pinna model that is as natural and accurate as possible. This gives a more realistic sense of spatial awareness and sound localization, whether it is from the front, back, sides or up and down, while achieving a better signal-to-noise ratio with more frontal focus than the previous option.
Watch our new video about Hybrid Noise Management™:
In the end, it is of course up to the HCP to use his or her experience and knowledge to adjust the hearing instruments based on the individual needs of each user. With this is mind, all these directionality options are designed to achieve the best user satisfaction for different listening situations to provide all the options possible for the user.
Appleton, J., & König, G. (2014). Improvement in speech intelligibility and subjective benefit with binaural beamformer technology. Hearing Review, 21(10), 40-42.
Beck, D., & Schum, D.J. (2005, November). Directional hearing aids: concepts and overview. Audiology Online. https://www.audiologyonline.com/articles/directional-hearing-aids-concepts-and-1012
Humes, L. E., Rogers, S.E., Main, A.K., & Kinney, D.L. (2018). The acoustic environments in which older adults wear their hearing aids: insights from datalogging sound environment classification. American Journal of Audiology, 27(4), 594-603.
Picou, E.M. (2020). MarkeTrak 10 (MT10) Survey Results Demonstrate High Satisfaction with and Benefits from Hearing Aids. Seminars in Hearing, 41(1), 21-36.
Preves, D.A., Sammeth, C.A., & Wynne, M.K. (1999). Field trial evaluations of a switched directional/omnidirectional in-the-ear hearing instrument. Journal of the American Academy of Audiology, 10, 273–284.
Ricketts, T.A., & Henry, P. (2002). Evaluation of an adaptive, directional-microphone hearing aid: Evaluación de un auxiliar auditivo de micrófono direccional adaptable. International Journal of Audiology, 41(2), 100-112.
Ricketts, T.A., & Dittberner, A.B. (2002). Directional amplification for improved signal-to-noise ratio: strategies, measurements, and limitations. In M. Valtente (Ed.), Hearing Aids: Standards, Options, and Limitations (2nd ed.), Thieme.
Walden, B., Surr, R., Cord, M., Grant, K., Summers, V., & Dittberner, A. (2007). The robustness of hearing aid microphone preferences in everyday environments. Journal of the American Academy of Audiology, 18, 358-79.