Enhancing Real-World Listening and Quality of Life with New Split-Processing Technology

Learning Outcomes

After this course learners will be able to:

• Describe the main principles in the Augmented Focus processing which is introduced in the Signia AX hearing device.
• Describe the protocol used in an international survey where Signia AX was assessed in real everyday life and compared to the participants’ own hearing aids.
• Describe the benefits of Signia AX reported by the survey respondents.

Introduction

Signia has a long track record of developing innovative amplification features that optimize wearer performance in all types of challenging listening situations. The goal of optimizing wearer performance across a range of divergent listening conditions was the main driver in the development of the Signia Augmented Xperience (AX) platform with the revolutionary Augmented Focus™ technology.

The ability of Augmented Focus to optimize the contrast between speech, which the wearer typically wants to follow and understand, and background sounds the wearer simply wants to be aware of, affects the entire listening experience. Signia AX with Augmented Focus specifically addresses the challenge of understanding speech in background noise, which is still one of the most dominant complaints made by hearing aid wearers (Picou, 2020).

Given these unique features, Augmented Focus provides several perceptual benefits for the wearer in a variety of listening situations. Some of these benefits have already been demonstrated: 1.) In a study conducted at the University of Northern Colorado, speech-in-noise testing was done in a simulated restaurant scenario, and the results showed that the performance with AX was superior both to the performance without Augmented Focus and to the performance offered by two main competitor devices (Jensen et al., 2021a). Furthermore, the AX performance was on par with the performance by a normal-hearing reference group. 2.) In a fully remote study done by Hörzentrum Oldenburg in Germany, a speech-in-noise test setup was established in the participants’ own homes. The results showed a significant speech-intelligibility benefit of Signia AX compared to the participants’ own hearing aids (Jensen et al., 2021b).

While these test results clearly indicate how Augmented Focus is able to make a difference for the wearer, the optimal way to explore the full potential of Augmented Focus is to fit Signia AX to wearers and ask them to use it in their own real-world listening situations. Toward that objective, an international survey was conducted in the United States, Germany and France. The survey included a comparison of Signia AX and the respondents’ own hearing aids. Using questionnaires in which respondents were able to evaluate various types of listening situations, the wearers compared Signia AX to their current devices.

Although the survey was conducted during the COVID-19 pandemic, in which social distancing guidelines were in place, the survey respondents continued to lead their daily lives in a variety of auditory surroundings that were captured in this survey.

Here, we present the final data from the survey, which offers some clinically relevant insights into how respondents’ listening challenges were addressed by Signia AX. The data provide some clear indications of the performance and benefits of Signia AX and Augmented Focus in real-world listening conditions, showing a high level of satisfaction with Signia AX as well as a clear preference over the respondents’ own hearing aids. The benefits are observed in various perceptual domains (e.g. improved speech intelligibility), but they are also observed in several quality-of-life-related domains (e.g. a stronger feeling of confidence).  

Augmented Focus™

Before reviewing the survey findings, let’s look at Augmented Focus, a new and fundamentally different approach to sound processing in a hearing aid. The basic underlying concept of Augmented Focus is to improve the wearer’s access to speech by increasing the contrast between speech and other sounds surrounding the wearer. It is believed that increasing the contrast between speech and surrounding sounds supports the brain in performing auditory scene analysis (Bregman, 1990). By helping the brain separate divergent sound streams from each other, Augmented Focus makes it easier for the listener to differentiate between speech and background noises. If, for example, a speech stream is separated from a stream of background noise, it will improve the listener’s ability to understand the speech. In contrast, if the two streams are not separated, they will be perceived by the listener as a single mixed stream of sound, which greatly reduces the probability that the listener will understand speech in the presence of noise.

The main principles of Augmented Focus are illustrated schematically in Figure 1. An important foundation of Augmented Focus is Signia’s unique beamformer technology, which is used to split the incoming sound into two separate signal streams. One stream contains sounds coming from the front of the wearer, while the other stream contains sounds arriving from the wearer’s back and sides.

Augmented Focus uses a dedicated processor to analyze the characteristics of the sounds in each stream. To optimally address the listening needs of the wearer, one stream is processed independently from the other stream across 48 channels. This unique split-processing approach allows one stream to be processed as a Focus stream where the aim of the processing is to optimize speech clarity and intelligibility. In contrast, the other stream is processed – completely differently – as a Surrounding stream in which the aim is twofold: 1) Provide clear and stable amplification of the wearer’s soundscape, and 2) Introduce a large contrast between the Focus stream and the Surrounding stream. The latter rationale typically provides more compression and a more powerful noise reduction for sounds in the Surrounding stream. In the example shown in Figure 1, the Focus area is in front of the wearer and the Surrounding area is in the back, as it often would be the case, but these areas can be in any direction relative to the wearer. Thus, a speech signal coming from the back can also be processed as a Focus stream, and a noise signal from the front can be processed as a Surrounding stream.

Figure 1. Schematic diagram showing the main Augmented Focus processing blocks. Beamformer technology is used to split incoming signals into two streams, which are processed separately. In this example, the speech coming from the front is detected and processed as a Focus stream, while the noise from behind is detected and processed as a Surrounding stream. The streams are mixed intelligently based on a soundscape analysis.

Following the independent processing of input sounds, the two streams are recombined in a mixing unit, which takes the information provided by the advanced Dynamic Soundscape Processing analysis into account. The Dynamic Soundscape Processing analysis was launched as part of the Xperience platform in 2019 and includes sound classification, motion sensor, signal-to-noise ratio estimation, Own Voice Processing (OVP), and classification of ambient modulations (see e.g. Froehlich et al., 2019a; Froehlich et al., 2019b; Froehlich et al., 2018). More detailed information on the unique properties of Augmented Focus processing is provided by Best et al. (2021).

The separate processing of the Focus and Surrounding streams offers several significant wearer benefits. It allows a speech signal in the Focus stream to be processed without being affected by sounds in the Surrounding stream. Augmented Focus typically provides more linear processing for speech, which results in the speech being perceived as clearer, and thus, enables it to more prominently stand out from the background noise. Further, the split processing improves the perception of the background sounds by offering a fast and precise adjustment of the gain for sounds in the Surrounding stream. This improves the stability of the background noise, and accordingly, the wearer’s perception of the entire soundscape is enhanced.

All these benefits can be perceived by Signia AX wearers during everyday listening situations. Accordingly, we designed this survey to focus on common real-world listening situations where these purported benefits are most likely to occur.

Methods

The methodological approach used for the survey was employed previously by Høydal et al. (2021). The approach involved asking a number of hearing care professionals (HCPs) in three different countries to fit some of their existing hearing aid wearers with Signia AX. These wearers then acted as respondents in the survey. The wearers’ task was to evaluate the Signia AX in their everyday life and compare the experience and performance with that offered by their own hearing aids.

Respondents

A total of 37 respondents completed the survey (18 in the US, 8 in Germany, and 11 in France). They included 13 females and 24 males and were between 28 and 91 years old (average: 72 years). All respondents were experienced hearing aid wearers, fitted bilaterally with hearing aids of various brands and models. The self-reported average age of their own hearing aids was four years.

Signia AX fittings

All respondents were fitted bilaterally with Signia Pure Charge&Go AX RIC devices (equipped with M-receivers). The ear coupling was determined by the HCP and based on each respondent’s hearing loss and their personal preferences. The fitting of the devices was completed in a routine manner, using the Signia AX First Fit rationale in Connexx 9.5. All devices were rechargeable, and respondents were able to charge their own devices. All respondents had the opportunity to use the Signia App, including the Signia Assistant, on their own smartphone during the survey period, but this was not mandatory.

Survey protocol

The protocol included one visit to the HCP’s clinic where the respondents were fitted with Signia AX. In cases where custom ear molds were used, an extra visit was scheduled to do ear impressions. The wearers were asked to complete an online questionnaire with some background questions (about age, gender, etc.) and questions about their experience wearing their own hearing aids. The respondents were then asked to use the Signia AX devices for two weeks. After two days, the HCPs were encouraged to contact the respondents to ensure none of them had experienced any noticeable problems with the new devices.

After two successive weeks of wearing Signia AX, the respondents received a link to a second questionnaire where they answered the same questions about their experience with Signia AX that they had answered for their own hearing aids. When the questionnaire was completed, the respondents were asked to switch back to their own hearing aids and wear them for a week, after which they received a link to a third questionnaire, asking for the third time the same survey questions. Respondents were then asked to switch to the Signia AX devices and use them for a week, before completing the fourth and final questionnaire. Thus, both Signia AX and own hearing aids were assessed two times. In addition to the same survey questions that appeared in the previous three questionnaires, the fourth and final questionnaire also asked respondents to state their preference between Signia AX and their own hearing aids in different domains. Figure 2 shows the timeline for the entire survey process.

Figure 2. The timeline of the survey protocol, showing when the different hearing devices were used and evaluated by the survey respondents during the four-week survey period.

Questionnaires

All questionnaires were administered online and could be completed using a smartphone, tablet or laptop, by following a link that was sent directly to the respondents via both email and text message.

The questionnaires included background questions (only first questionnaire), questions on satisfaction in different listening situations rated on a seven-point Likert-type scale going from “very unsatisfied” to “very satisfied,” a question on whether the respondent would recommend the hearing aids to others, select questions from the Speech, Spatial and Qualities of hearing questionnaire (SSQ; Gatehouse & Noble, 2004) rated on a scale from 0 to 10, and six questions on the preference between Signia AX and the respondents’ own hearing aids in different domains (only final questionnaire).

Results

Satisfaction

In each of the four questionnaires, the respondents answered the following questions about their satisfaction with the given hearing devices:

• Overall, how satisfied are you with the hearing aids?
• How satisfied are you with the overall sound quality of the hearing aids?
• How satisfied are you with the hearing aids with respect to understanding speech, across all communication situations?
• How satisfied are you with the sound of your own voice when speaking with others with the hearing aids?
• How satisfied are you with how the hearing aids look when you wear them?
• How satisfied are you with the physical comfort of the hearing aids?

The satisfaction ratings reported below are the ratings made in questionnaires 3 (own hearing aids) and 4 (Signia AX), after respondents had worn both sets of devices and were maximally acclimatized to Signia AX. Figure 3 shows the mean ratings of satisfaction provided by the respondents for each question. In the plot, the seven-point Likert-type scale has been transformed to a seven-point numeric scale from 1 (very unsatisfied) to 7 (very satisfied).

Figure 3. The mean ratings of satisfaction with Signia AX and own hearing aids, averaged across all participants. Both overall satisfaction with the devices and satisfaction within five specific domains were rated.

Figure 3 shows that the respondents rated Signia AX higher than their own hearing aids in all six domains. Even though respondents were largely satisfied with their own hearing aids, as indicated by mean ratings in the upper half of the scale, Signia AX was able to provide a consistent and noticeable improvement.

The satisfaction ratings were analyzed using a general linear mixed model, with device (Signia AX and own HA), question (1-6), and assessment number (first and second) as fixed effects, and with respondent (1-37) as a random effect. The result of the analysis showed highly significant main effects of both device, question, and respondent (all p < .00001), whereas there was no significant effect of assessment number (p = .32). A Tukey post-hoc test was used to assess the difference between AX and own HAs for each question. This analysis showed significant differences for the questions on overall satisfaction, sound quality, speech intelligibility and own voice (all p < .01), while the observed differences on the questions about physical appearance and comfort were non-significant (p = .75 and p = .71, respectively).

The effect of Augmented Focus is a likely explanation for the higher ratings of satisfaction to the questions on sound quality and, in particular, speech intelligibility, where AX increases the mean rating by an impressive 1.4 scale points on the 7-point scale, compared to own hearing aids. The higher satisfaction ratings observed for the question on own voice can be attributed to the Own Voice Processing (OVP), a mainstay feature integrated into Signia AX.

Besides the audiological benefits leading to higher levels of satisfaction, the design of the Pure C&G AX devices used in the survey and the improved physical fit offered by the new EarWear 3.0 receivers, ear tips and sleeves are likely to have resulted in higher satisfaction ratings on the questions related to both physical appearance and physical comfort. The fact that the differences were not statistically significant is partly due to the rather high ratings by respondents of own hearing aids in these domains, creating a ceiling effect. It should be noted, however, that the absolute mean ratings of physical appearance and comfort occurred at approximately the same level on the Likert scale as the other AX satisfaction ratings.

Another way to look at the same survey data is to calculate the percentage of respondents who expressed satisfaction, as indicated by providing one of the three highest ratings, i.e., “somewhat satisfied,” “satisfied” or “very satisfied.” These percentages are shown in Figure 4 for Signia AX compared to the respondents’ own hearing aids for the six questions.

Figure 4. Percentage of respondents expressing satisfaction in the six questions for which the mean ratings were presented in Figure 3.

Overall, Figure 4 shows the same trend as already seen in Figure 3: a marked increase in satisfaction associated with Signia AX. The level of satisfaction is generally high, and it is notable that 84% of the respondents expressed an overall satisfaction with AX, compared to 51% expressing satisfaction with their own hearing aids. For the five other questions, the share of respondents reporting satisfaction with AX varied between 78% and 86%, as compared to 43% to 70% reporting satisfaction with their own hearing aids. It should be noticed that Signia AX almost doubles the share of satisfied respondents (from 43% to 81%) for ratings of speech intelligibility. This is another clear indication of the positive effects offered by the Augmented Focus processing.  

SSQ

The respondents answered select items from the SSQ questionnaire. Each of the items in the SSQ define a specific listening situation. Respondents were asked to rate their experience with Signia AX and their own hearing aids on a scale from 0 to 10 (higher numbers indicate more wearer benefit). For example, the first item said “You are talking with one other person and there is a TV on in the same room. Without turning the TV down, can you follow what the person you’re talking to says?” In this case, the end points of the rating scale were defined as “Not at all” (0) and “Perfectly” (10).

Figure 5 shows the mean ratings of respondents’ own hearing aids and Signia AX for the 13 SSQ items included in the survey. As in the case of the satisfaction ratings, the ratings from the second assessment of own hearing aids and Signia AX are shown in the plot. Figure 5 includes brief descriptions of the listening situations queried by the SSQ. Furthermore, the figure includes the mean SSQ ratings of a group of normal-hearing adults with almost the same average age (70 years) as the survey respondents, reported by Banh et al. (2012).

For some of the SSQ items, the mean ratings are based on fewer than 37 responses, due to respondents using the N/A response option. They were asked to do so if they had not experienced the type of listening situation asked about. For some of the N/A responses, COVID-19 social distancing measures is the likely primary reason for the N/A answers. Thus, the lowest number of responses (25) was observed for item B that describes a situation in a busy restaurant that many respondents did not encounter during the survey period.

Figure 5. Mean ratings of the SSQ items included in the survey, with short descriptions of the listening situations that were rated. A high rating always indicates better performance.

Figure 5 shows that respondents rated Signia AX higher than their own hearing aids across all 13 SSQ items. In all cases, the mean difference exceeded one scale point, and for some items, the difference even approached two scale points. The SSQ ratings were analyzed in the same way as the satisfaction ratings, using a general linear mixed model with device (Signia AX and own HA), item (A-M), and assessment number (first and second) as fixed effects, and with respondent (1-37) as a random effect. The result of the analysis showed highly significant main effects of both device, item, and respondent (all p < .00001), whereas there was no significant effect of assessment number (p = .090). A Tukey post-hoc test was used to assess the difference between AX and own HAs for each item. This analysis showed significant differences (all p < .01) for all items except item J about own voice (p = .069). However, when the analysis was done based only on the ratings from the second assessment, the mean difference between the Signia AX and own hearing aids on this item was statistically significant (p = .041), indicating that the own-voice benefit was enhanced by acclimatization to Signia AX.  

Among the noteworthy observations in Figure 5 are the benefits provided by Signia AX in situations involving speech communication (items A, B, C, D and E). In these situations, Augmented Focus with its ability to process speech and surroundings separately is a likely primary explanation for the improvements. Also, the split processing is a likely explanation for the improved separation of sounds (items G and H), the improved sound quality of other voices (item I) and the improvements in listening effort-related domains (items K, L and M).

It is noteworthy that one of the largest improvements, as measured by the increase in mean rating, was observed for the item on listening effort in conversations (L) where the mean rating increased from 4.5 for own hearing aids to 6.4 for Signia AX.

As it was the case in the satisfaction question about own voice, the improvement with Signia AX on the item about naturalness of own voice (J) can be directly linked to the effect of Signia’s OVP technology – a unique feature found on Signia devices for the past several years.

While the respondents’ SSQ ratings for Signia AX were higher than the ratings for their own hearing aids, it is obvious that the mean ratings for Signia AX were somewhat below the SSQ’s scale maximum of 10. Here, it should be acknowledged that many of the listening situations covered by the SSQ items are difficult even for normal-hearing listeners. This becomes apparent when comparing with the normal-hearing reference data included in Figure 5. It can be seen that for some items, the Signia AX mean ratings are approaching and – in a few cases – even slightly exceeding the normal-hearing ratings, while none of the mean ratings of own hearing aids are close to the normal-hearing ratings.

Preference

In the fourth and final questionnaire, the respondents were asked to state their preference between Signia AX and their own hearing aids for the following questions:

• In your experience, which hearing aids require the least listening effort in daily life?
• In your experience, which hearing aids provide the best speech understanding across all listening situations?
• In your experience, which hearing aids provide the most exciting listening experience in your daily life?
• In your experience, which hearing aids make your feel more energized (less tired/less strained) in your daily life?
• In your experience, which hearing aids make you feel more confident in your daily life?
• Overall, which hearing aids do you prefer?

A ‘forced choice’ approach was used in which the respondents had to choose between two response options: own hearing aids and Signia AX. The distribution of preferences among the respondents for each of the six questions is shown in Figure 6.

Figure 6. Percentage of respondents stating a preference for own hearing aids and Signia AX, respectively, for five specific domains as well as for overall preference.

Consistent with the absolute ratings reported above, the data in Figure 6 show a clear and consistent preference for Signia AX over own hearing aids. For the first five questions, the share of respondents preferring Signia AX varied between 73% and 81%, while 78% stated an overall preference for Signia AX. For all six questions, the preference for Signia AX was statistically significant according to a two-tailed binomial test with Bonferroni correction for multiple comparisons (all p < .05).

Among the questions, respondents were asked which device provided the most “exciting listening experience.” Although this may seem like an unusual question, given the unique split processing of Augmented Focus, posing this question to respondents contributes to understanding this feature’s potential multifaceted quality of life benefit. Additionally, respondents were asked which device made them feel more energized and confident. Results of these questions, illustrated in Figure 6, demonstrate a clear preference for Signia AX compared to the respondents’ own hearing aids. This finding suggests Signia AX not only affects the wearers’ listening experience in isolation, but positively affects other aspects of their quality of life.

The preference for AX is in agreement with the answers to the question about whether respondents would recommend the hearing aids to others, which was included in each questionnaire. In the second and final assessment of the devices, 84% of the respondents indicated they would recommend Signia AX, whereas only 68% were prepared to recommend their own hearing aids.

Discussion

The results of this wearer survey indicate several outcomes that favor Signia AX and its Augmented Focus processing. The survey data demonstrate several benefits that can be associated with the split processing of Augmented Focus, including clear and consistent benefits in several aspects of speech understanding. Further, the data indicate these improvements were observed in questions related to other domains of hearing, including listening effort, sound quality judgements and the ability to separate sounds in one’s soundscape.

Besides the traditional audiological outcome domains, the survey also tapped into quality of life domains, which are likely to be affected by a hearing loss. For example, the respondents expressed a clear preference for Signia for “providing an exciting listening experience.” Further, the respondents stated a clear preference for Signia AX with respect to their own feeling of being energized and confident in daily life. These findings indicate Signia AX improves the quality of life for the wearer.

The unambiguous preference for Signia AX, observed in both the satisfaction and preference ratings, correspond well with the SSQ results, which also showed a strong preference for Signia AX over the respondents own hearing aids. Interestingly, when compared to the normal-hearing reference data published by Banh et al. (2012), the mean SSQ ratings were quite comparable to the normal-hearing ratings in many situations, indicating that the mean performance of the AX wearers was on par with average normal-hearing performance in these situations. These observations are in agreement with findings from another recent Signia AX study (Jensen et al., 2021a) in which Augmented Focus processing was shown to provide performance on par with a normal-hearing reference group in simulated restaurant scenario. In that study it was demonstrated that activation of Signia AX’s binaural beamforming offered performance for the participants with hearing loss that even exceeded normal-hearing performance in a simulated party scenario.

In addition to the split processing of Augmented Focus, the new Signia AX platform has several other improvements that may contribute to the enhanced listening experience observed in this survey. For example, the faster binaural synchronization provides a smoother listening experience when switching between processing modes, and the extended input dynamic range improves the perception of loud sounds. These new feature enhancements have been integrated with several existing Signia features, such as OVP and motion sensor technology, and it is, of course, the combination of these features that contribute to the total listening experience evaluated in this survey.

Summary

In an international survey, the performance of Signia AX was evaluated in real-world listening and compared to the performance of the respondents’ own hearing aids. The data from the 37 respondents who completed the survey indicate a considerably high level of satisfaction with Signia AX relative to their own devices, with 84% of respondents reporting to be satisfied with Signia AX. Furthermore, a clear improvement provided by Signia AX compared to the respondents’ own hearing aids was observed across a variety of questions included in the survey, and 78% of the respondents stated an overall preference for Signia AX over their own hearing aids.

Many of the Signia AX benefits observed in the survey data can be attributed to the Augmented Focus processing that allows separate and optimized processing of speech and background sounds. The preferences were observed within audiological outcome domains such as speech intelligibility, sound quality and listening effort. They were also observed in quality-of-life domains where respondents reported to feel more energetic and confident when wearing Signia AX. These findings suggest that Signia AX has the potential to improve both the listening experience and, more generally, the quality of life of the wearers. In a comparison with published normal-hearing reference data, the results from the SSQ items indicated that the wearers’ performance with AX approached normal-hearing performance in several challenging listening situations.

Acknowledgements

We would like to thank all the hearing care professionals and all the hearing aid wearers from the United States, Germany and France who participated in this survey.

References

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