Cearvol Diamond X1 vs MDHearing VoltMax
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 available for $199, earning a B grade with a SoundScore of 3.7/5 in our lab testing. This visible-in-ear style device ranks #30 among 65 OTC hearing aids tested, placing it in the top 45% of its category. The Diamond X1 delivers a mixed performance profile with one notable strength: music streaming. With a score of 4.1/5, it performs 2.18 points above the category average—a substantial margin that makes it appealing for users who value audio entertainment through their hearing aids. Feedback handling is excellent at 4.5/5, providing stable performance during typical daily movements. Both iPhone and Android streaming are supported with rechargeable batteries for convenience. Speech performance presents a more modest picture. Speech in quiet scores 2.8/5, which is above the category average but only mixed in absolute terms. Speech in noise measures 1.7/5—above the category average of 1.48/5, though still low overall. Own-voice comfort is a weakness at 1.7/5, falling 0.81 points below the category average, which may cause your own voice to sound unnatural or boomy. The Diamond X1 is best suited for budget-conscious consumers who prioritize music and media streaming over maximum speech clarity. Those seeking stronger speech performance in challenging listening environments may want to consider higher-scoring alternatives in this price range, such as the Elehear Beyond or Apple AirPods Pro 2.

MDHearing VoltMax
The MDHearing VoltMax is a behind-the-ear OTC hearing aid priced at $699, earning a B grade with a SoundScore of 3.0/5 in our lab testing. This mid-priced device ranks #62 of 65 in the OTC Hearing Aid category, placing it in the bottom portion of tested products. In our standardized testing, the VoltMax demonstrates excellent feedback handling at 5.0/5, scoring 0.46 points above the category average. This means users are unlikely to experience whistling or squealing during typical wear. However, speech performance presents significant challenges—speech in quiet scores a low 1.9/5 (0.93 points below average), while speech in noise scores 1.0/5 (0.48 points below average). These results suggest limited benefit for understanding conversation in both calm and challenging listening environments. Music streaming is a notable weakness, scoring 0.0/5 and falling 1.92 points below the category average. Users who prioritize streaming audio content from their phones should consider alternatives. Own-voice comfort is mixed at 2.4/5, roughly matching the category average. At this price point, several alternatives offer substantially stronger performance. Devices like the Yeasound RIC800 and Sony CRE-E10 score above 4.5/5 at similar or lower prices. The VoltMax may appeal to users who prioritize feedback-free wear and basic amplification with rechargeable convenience, but those seeking stronger speech clarity should explore higher-performing options in this price range.
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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
Using MUSHRA scenes (Tuned)
Fitting configuration for tuned fit