Autiphon U0 Series vs Phonak Sphere Infinio Ultra
Side-by-side HearAdvisor lab results with SoundGrades, expert pick badges, and the same visualizations we use in product reviews.

Autiphon U0 Series
The Autiphon U0 Series is a budget amplification product priced at $99, earning a C grade with a SoundScore of 2.9/5 in HearAdvisor's lab testing. This visible-in-ear device ranks #6 of 8 amplification products tested, placing it in the top 63% of its category. In our testing, the U0 Series demonstrates a mixed performance profile. Its standout strength is excellent feedback handling, scoring a perfect 5.0/5—well above the category average by 0.72 points. This means users are unlikely to experience whistling or squealing during normal use. Speech in quiet environments scores 2.3/5, which is 0.22 points above the category average, though still only mixed in absolute terms. The device shows notable limitations in other areas. Speech in noise performance is low at 1.0/5, falling 0.37 points below the category average—meaning challenging listening environments like restaurants or gatherings will be difficult. Music streaming capability is essentially non-functional, scoring 0.0/5 and sitting 1.16 points below category average. The Autiphon U0 Series is best suited for budget-conscious users who primarily need basic amplification in quieter settings and prioritize freedom from feedback issues. Those who frequently encounter noisy environments or want to stream music should consider alternatives. At this price point, the HSKLock Hearing Aid offers slightly higher overall performance at 2.98/5.
Choice

Phonak Sphere Infinio Ultra
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.
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Performance metrics
Scale 1-5 (Tuned)
Lab metric by fit
Scale 1-5 (Tuned)
Speech level
Adjust input dB (Tuned)
Amplification (REIG)
Insertion gain at 65 dB (Tuned)
Audio scenes
Recorded samples (Tuned)
Fitting configuration for tuned fit