Phonak Sphere Infinio Ultra vs Signia Styletto AX

The Phonak Sphere Infinio Ultra is a premium behind-the-ear prescription hearing aid priced at $4,898. In HearAdvisor's lab testing, it earned an A grade with a SoundScore of 4.9/5, placing it in the top 5% of the 39 prescription hearing aids tested and ranking #3 in the category. This device demonstrates exceptional speech performance in our testing. Speech in noise scored 4.5/5—an excellent result that measures 2.40 points above the category average of 2.11/5. Speech in quiet also performed strongly at 4.3/5, which is 0.92 points above the category average. These results suggest the Sphere Infinio Ultra may particularly benefit users who frequently navigate challenging listening environments like restaurants or group conversations. Music streaming delivered a solid 3.3/5, measuring 0.54 points above category average. Own-voice comfort scored 2.8/5, which is above the category average by 0.10 points but remains mixed in absolute terms. Feedback handling measured 4.2/5—strong in absolute terms, though 0.52 points below the category average of 4.72/5. The Sphere Infinio Ultra is best suited for users seeking top-tier speech clarity who prioritize performance in noisy environments and are prepared to invest at the premium price tier. Those seeking similar sound quality at a lower price point may also consider the Phonak Sphere Infinio, which scored 4.98/5 in our testing.

The Signia Styletto AX is a premium prescription behind-the-ear hearing aid that earned an A grade with a SoundScore of 4.3/5 in our lab testing, ranking #21 of 39 prescription hearing aids tested. Priced at $4,398, this 2022 release features a distinctive slim design with rechargeable batteries and iPhone streaming capability. In our testing, the Styletto AX demonstrated strong speech clarity in quiet environments, scoring 4.0/5—0.63 points above the category average. Speech in noise performance was above average at 2.3/5 (+0.17 vs category), though this remains mixed in absolute terms, suggesting challenging listening situations may still require additional strategies. Own-voice comfort scored a solid 3.0/5, sitting 0.30 points above average. Music streaming quality measured 3.1/5, performing 0.34 points above the category average for solid audio fidelity when streaming from compatible devices. Feedback handling scored 3.9/5—solid in absolute terms, though 0.82 points below the category average of 4.72/5, which is worth noting if feedback stability is a priority. The Styletto AX has earned Expert's Choice Awards in both 2023 and 2024. However, buyers in this premium price tier should be aware that several competitors offer higher SoundScores, including the Phonak Sphere Infinio (4.98/5) and Oticon Intent (4.83/5). The Styletto AX may appeal most to those prioritizing its sleek aesthetic and strong quiet-environment speech performance over maximum scores in noise or feedback handling.