Cearvol Diamond X1 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.

Cearvol Diamond X1
The Cearvol Diamond X1 is a budget-priced OTC hearing aid that earned a B grade with a SoundScore of 3.7/5 in our lab testing, placing it in the top 45% of OTC devices. At $199, it represents an accessible entry point for those exploring hearing amplification. The Diamond X1's standout performance is in music streaming, scoring 4.1/5—a strong result that sits 2.18 points above the OTC category average. This makes it notably capable for users who prioritize audio entertainment through their hearing devices. Feedback handling is also excellent at 4.5/5, meaning users should experience minimal whistling during normal use. However, speech performance presents limitations. Speech in quiet scores a mixed 2.8/5, and speech in noise registers at 1.7/5. While both metrics technically sit above category averages (+0.03 and +0.22 points respectively), they remain low in absolute terms—important context for anyone prioritizing conversation clarity. Own-voice comfort is another weakness, scoring 1.7/5, which is 0.81 points below the category average and may affect how natural users sound to themselves. The Diamond X1 is best suited for budget-conscious consumers who value music streaming quality and aren't heavily reliant on challenging listening environments. Those who prioritize speech understanding in noise or natural own-voice perception may want to consider alternatives in this price range, such as the higher-scoring Elehear Beyond or Apple AirPods Pro 2.
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