Sennheiser All-Day Clear Slim Hero
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Sennheiser All-Day Clear Slim Expert Review

Premium OTCReleased 2023

Our lab tested the Sennheiser All-Day Clear Slim using standardized measurements on an acoustic manikin to evaluate real-world hearing aid performance. This independent review covers speech clarity, noise handling, streaming quality, and amplification accuracy across multiple fit conditions.

Dr. Steve TaddeiDr. Steve Taddei, Au.D.Lab Director & Reviewer
Dr. Abram BaileyDr. Abram Bailey, Au.D.Fact Checker / Editor
How We Test

The Sennheiser All-Day Clear Slim is a premium behind-the-ear OTC hearing aid priced at $1,499, earning an A grade with a SoundScore of 4.1/5 in our lab testing. This places it in the top 23% of the OTC hearing aid category, ranking #16 among 65 tested devices.

In our testing, the All-Day Clear Slim demonstrates notable strengths in music streaming, scoring 3.8/5—a solid result that sits 1.88 points above the category average. This makes it one of the stronger performers for users who prioritize audio quality when streaming from their phone. Feedback handling is excellent at 5.0/5, measuring 0.46 points above the category average, meaning users can expect stable performance without whistling during typical daily activities.

Speech clarity in quiet environments is solid at 3.6/5, coming in 0.85 points above the category average. However, speech in noise performance is low at 1.5/5, matching the category average—a common limitation across OTC devices. Own-voice comfort scores 1.9/5, which is 0.61 points below the category average, suggesting some users may notice their own voice sounds different or hollow.

The All-Day Clear Slim includes rechargeable batteries and supports streaming to both iPhone and Android devices with hands-free functionality. At its price point, alternatives like the Lucid Tala and Audicus Omni 2 offer higher overall scores, though the Sennheiser may appeal to those who value the brand's audio heritage and prioritize music streaming quality over speech-in-noise performance.

Reliable & Repeatable Lab Results

Quality data starts with quality recordings. HearAdvisor worked with GRAS to build a no-compromise front end so every test is repeatable and reliable.

Learn more
Steve in HearAdvisor Lab

Lab Assessment

Where the Sennheiser All-Day Clear Slim Excels and Falls Short

Our verdict weighs measured performance across five lab metrics against the device's premium price point. The card below summarizes the overall grade, ranking within the OTC category, and key strengths and limitations identified through testing.

Sennheiser All-Day Clear Slim Hero
HearAdvisor
Sennheiser All-Day Clear Slim
4.1HearAdvisor SoundScoreGrade A
As it sounds out of the box
Bottom Line

The Sennheiser All-Day Clear Slim delivers excellent feedback handling and strong music streaming, making it a premium OTC option for entertainment-focused users.

Top 23% of OTC Hearing Aid
Strengths
  • Excellent feedback handling5.0/5
  • Strong music streaming+1.88 vs category
  • Solid speech clarity in quiet settings3.6/5
Drawbacks
  • Own voice quality below average-0.61 vs category
  • Low speech-in-noise performance1.5/5
  • Premium price at $1,499
Metric Breakdown

Five Lab Metrics for the Sennheiser All-Day Clear Slim

Each bar in the card below represents a distinct measurement from our acoustic testing protocol. These five metrics evaluate speech intelligibility, noise management, streaming fidelity, own-voice naturalness, and feedback stability.

As it sounds out of the box
Speech in quiet
New
3.6 out of 5, average of tested hearing aids 2.9

How clearly speech comes through in calm, one-on-one surroundings.

Speech in noise
New
1.5 out of 5, average of tested hearing aids 1.6

Speech understanding against loud background noise — the toughest everyday test.

Own voice
1.9 out of 5, average of tested hearing aids 2.6

How natural your own voice sounds while wearing the aids, without a boomy, plugged-up quality.

Music streaming
3.4 out of 5, average of tested hearing aids 2.1

Sound quality of music streamed to the hearing aids over Bluetooth.

Feedback handling
5.0 out of 5, average of tested hearing aids 4.6

Resistance to the whistling and squealing caused by acoustic feedback.

Average of 112 hearing aids tested

Scores use HearAdvisor’s public scoring scale and are based on measurements from our acoustic test chamber.

Scoring methodology

Fit Conditions

Initial and Tuned Performance for the All-Day Clear Slim

We measured this behind-the-ear device in both its out-of-box Initial fit and after completing the manufacturer's Tuned personalization process. The summaries below describe how each configuration performed against prescriptive amplification targets.

Lab Test Summary

In initial fit testing with closed sleeve coupling, the All-Day Clear Slim achieved a normalized score of 4.1/5. Speech in quiet performed solidly at 3.6/5, while speech in noise was low at 1.5/5. Music streaming measured 3.4/5, and feedback handling was excellent at 5.0/5. Own-voice comfort was low at 1.9/5, below the category average by 0.61 points, which may mean some users notice occlusion effects with their own voice.

What is HearAdvisor's Initial Fit?

The Initial Fit approximates the most likely settings and eartips for a typical moderate hearing loss. Results are measured across the same 72 acoustic scenes in our custom-built lab, then scored on a 5-star scale using an auditory model.

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Amplification Data

Insertion Gain Measurements for the All-Day Clear Slim

The graph below plots measured insertion gain against prescriptive targets across the frequency range. This visualization shows how closely the device's actual amplification matches the output recommended for the programmed hearing profile.

Graph

Audio Evidence

Manikin Recordings of the Sennheiser All-Day Clear Slim

We captured audio samples through the hearing aid while fitted on our acoustic manikin in controlled test conditions. Compare these recordings to the unaided reference below to hear how the device processes speech and environmental sound.

Lab Recordings
Adjust volume to make "No hearing aids" as loud as it would be in the real world, without hearing aids. Remove hearing aids while auditioning. High-quality headphones will improve results!
Sennheiser All-Day Clear Slim Lab

Test Configuration

Documentation for the All-Day Clear Slim Lab Session

The notes below record the specific settings, firmware version, and test parameters used during our evaluation. This documentation ensures our measurements for this rechargeable streaming device can be referenced and replicated.

Lab Notes
Initial Fitting
Tuned Fitting
Ear Coupling
Sleeve Closed
Sleeve Closed
Specs
Behind Ear
Behind Ear
Rechargeable Batteries
Rechargeable Batteries
iPhone Streaming
iPhone Streaming
Android Streaming
Android Streaming
Hands-Free
Hands-Free
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