Oticon Zeal vs Sennheiser All-Day Clear Slim
Side-by-side HearAdvisor lab results with SoundGrades, expert pick badges, and the same visualizations we use in product reviews.
Choice

Oticon Zeal
The Oticon Zeal is a premium prescription hearing aid in the invisible-in-ear style, carrying an A grade with a SoundScore of 4.7/5 in our lab testing. Priced at $4,798, it ranks #6 among 39 prescription hearing aids tested, placing it in the top 13% of its category. Speech performance is where the Zeal truly excels. Our testing measured an excellent 4.9/5 for speech in quiet—1.48 points above the category average—making it one of the strongest performers for everyday conversations. Speech in noise also scores a solid 3.0/5, sitting 0.93 points above the category average of 2.11/5, indicating reliable performance in moderately challenging listening environments. Music streaming quality registers at a solid 3.3/5, which is 0.54 points above the category average. However, the Zeal shows some limitations in other areas. Own-voice comfort scores a mixed 2.0/5, falling 0.70 points below the category average—something to consider if own-voice naturalness is a priority. Feedback handling measures at 3.3/5, which is solid in absolute terms but sits 1.42 points below the category average of 4.72/5. The Oticon Zeal is best suited for wearers who prioritize exceptional speech clarity and want a discreet, invisible-in-ear form factor. Those especially sensitive to feedback or own-voice effects may want to discuss these trade-offs with their hearing care provider during fitting.
Choice

Sennheiser All-Day Clear Slim
The Sennheiser All-Day Clear Slim is a premium OTC behind-the-ear hearing aid priced at $1,499, earning an A grade with a SoundScore of 4.1/5. This places it in the top 23% of OTC hearing aids tested in our lab, ranking #16 among 65 devices in its category. This device excels in areas that reflect Sennheiser's audio heritage. Music streaming quality is a standout strength, scoring 3.8/5—a solid result that's 1.88 points above the OTC category average. Feedback handling is excellent at 5.0/5, meaning users can expect stability without whistling during typical use. Speech in quiet environments also performs well at 3.6/5, sitting 0.85 points above average for the category. However, the All-Day Clear Slim shows limitations in other areas. Speech in noise scores 1.5/5, matching the category average but representing a low absolute score that may challenge users in noisy restaurants or group conversations. Own-voice comfort is below average at 1.9/5, which could affect how natural users sound to themselves during conversation. The All-Day Clear Slim is best suited for consumers who prioritize music streaming and media consumption alongside hearing support, and who spend more time in quieter environments. Those frequently navigating noisy social situations may want to compare against higher-ranked competitors in this price range, such as the Lucid Tala or Audicus Omni 2, which achieve stronger overall scores.
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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)
Fitting configuration for tuned fit