
Spheric Speech Clarity: Findings from PARC lab measures
Results from a Phonak Audiology Research Center study highlight some of the benefits of Spheric Speech Clarity in Audéo Sphere Infinio, improving speech understanding in noise and reducing listening effort, compared to other noise management technologies.
One of the unique challenges inherent in clinical research within the hearing aid industry is developing study methods that effectively assess the benefits of new technology, while maintaining clinical and ecological relevance. This was certainly the case when the team at the Phonak Audiology Research Center (PARC) designed the clinical investigation of Spheric Speech Clarity (SSC).
Spheric Speech Clarity
SSC is a denoising system exclusively available in Audéo Sphere Infinio devices, powered by the proprietary DEEPSONIC chip. This chip utilizes a deep neural network (DNN) designed to separate speech from noise in real-time, regardless of direction. It differs from traditional noise reduction technology, which relies on directional microphones. Consequently, evaluating the benefits of SSC required adapting the usual methods for assessing hearing aid noise management.
Following several months of exploratory work to identify the experimental tasks and conditions reflective of real-world scenarios where SSC is designed to perform optimally, data collection with the finalized protocol began in the PARC lab in spring 2024.
It was expected that the study would demonstrate SSC’s ability to improve speech understanding in noise and subjective listening effort —and the results were encouraging. Learn more about our findings below.
Methodology
Speech understanding in noise and listening effort were assessed in a group of 27 adults between the ages of 58 and 93 with moderate to moderately severe bilateral hearing loss.
Speech understanding in noise
Speech understanding was measured by presenting sentences at random from one of four loudspeakers positioned to the left and right of the participant, while continuous noise was presented from the same four loudspeakers, plus a fifth loudspeaker positioned directly behind the participant. Figure 1 (left panel) shows the acoustic setup with four loudspeakers surrounding the participant.
Each sentence contained a color and a number (e.g., “Ready, Baron, go to blue four now”) which participants were instructed to select on a computer screen after each sentence. Figure 1 (right panel) shows the response screen used to select answers.

Performance on this task was measured with Phonak Audéo Sphere Infinio devices ─once with SSC activated at the default setting (“SSC on”) and once with it deactivated (“SSC off”) ─as well as with current receiver-in-canal (RIC) devices from two competitors. Participants were blinded as to which devices/program they were listening to at any given time during testing.
Subjective listening effort
Listening effort was assessed using the Adaptive Categorical Listening Effort Scaling (ACALES) test, in which participants rated their perceived listening effort on a scale of 1 (“effortless”) to 13 (“extremely effortful”) for sentences presented in noise across a range of signal-to-noise ratios (SNRs).
In this task, sentences were presented from a loudspeaker position directly in front of the participant, while noise was presented from two speakers to their left and two to their right. Since this task is fairly lengthy, the ACALES was completed using the Audéo Sphere devices with and without SSC, but competitor devices were not used.
Results
Instead of calculating percentage scores, results of the speech understanding in noise task were analyzed using an odds ratio to determine if the probability of providing a correct response differed across hearing devices.
This analysis revealed that participants were significantly more likely to understand speech from any direction with SSC activated compared to disabled (Figure 2, left panel).
Similarly, Audéo Sphere devices yielded significantly better speech understanding performance than devices from other manufacturers (Figure 2, right panel). This indicates that participants were far more likely to correctly identify sentences in noisy environments when using SSC.

Results of the ACALES test showed that across ratings (1-13), SNRs were, on average 2.9 dB, more challenging with SSC than without it. This suggests that SSC allowed listeners to tolerate less favorable listening conditions without an increase in their perceived listening effort.
Conclusion and next steps
This investigation provided evidence that Spheric Speech Clarity, available in Audéo Sphere Infinio, improves speech understanding in complex noisy environments and reduces perceived listening effort.
To further validate these benefits, the next phase of this study focused on determining if SSC’s benefits extended to real-world listening scenarios. The methodology and findings from this field trial will be detailed in a future post.
To learn more about SSC, we invite you to explore previous blog articles: Dream Big – Your hearing aids can handle it and Audéo Sphere™: Advancing speech understanding with AI.
To learn more about Audéo Sphere Infinio devices, please visit our product pages. For insights from this study, refer to the Field Study News available in the Phonak Evidence Library – Link.