Quick summary: The “Bluetooth 5.4” printed on an earbud box does not mean better sound, because sound quality lives in the codec. ANC reduces the noise you hear, while ENC only reduces the noise the other person hears when you make a call. And however good the earbuds are, a safe listening level is still a matter of both volume and time: 80 dBA for about 40 hours a week, and every 3 dB increase halves the allowed time.
Key points
- Bluetooth 5.4 does not mean better sound. The version number tells you about the chip, not about the codec, latency or fidelity.
- ANC and ENC serve two different people. ANC is for the wearer, ENC is for the person on the other end of the line.
- Safe listening has concrete numbers. 80 dBA for 40 hours a week according to WHO–ITU; at 89 dBA only about 43 minutes a day remain.
- ANC lowered the listening level by about 2.5–3 dB in one small study, but it is not hearing protection equipment.
1. The problem: three numbers on the box are easy to misread
A TWS earbud labelled “Bluetooth 5.4, ENC, 20–24 hours of battery life” contains three pieces of information that are very easy to misunderstand:
- “5.4” is easily read as better sound than “5.0”.
- “ENC” is easily confused with noise cancelling while listening to music.
- “20–24 hours” is easily taken to mean continuous listening on a single charge.
Behind the specifications lies a bigger issue. A pooled analysis of 33 studies estimated that roughly 0.67–1.35 billion young people worldwide are at risk of hearing damage from unsafe listening [7]. Personal listening devices are one of the two main sources of exposure, alongside noisy entertainment venues. So choosing and using earbuds is not only a matter of convenience, but also of protecting your ears.
2. Does Bluetooth 5.4 make earbuds sound better than Bluetooth 5.0?
Not necessarily. Bluetooth Core 5.4, released in January 2023, added four features: Periodic Advertising with Responses (PAwR), encrypted advertising data, the GATT security levels characteristic and advertising coding selection [1]. All four target one-to-many systems, typically electronic shelf labels in shops, not audio quality.
Sound is decided at another layer. On Bluetooth Classic, audio passes through a codec (SBC by default, plus optional codecs). On LE Audio, the foundation is Isochronous Channels, available since Core 5.2, together with the LC3 codec, which delivers better quality than SBC at lower bit rates [2]. The codec actually used is the intersection of what the phone and the earbuds both support.
In short: the “Bluetooth 5.4” label tells you the version of the chip’s radio core. The published specifications of the OH-T100, OH-T101 and OH-T102 state Bluetooth 5.4 and a range of 10–15 m without obstacles, but do not list codecs. If you watch a lot of video or play games, ask about this. Also remember that the range is measured without obstacles; the human body and walls attenuate the 2.4 GHz signal, so real-world range is usually shorter.
3. How do ANC and ENC noise cancelling differ?
ANC reduces the noise you hear; ENC reduces the noise other people hear when you make a call.
ANC (Active Noise Cancellation) is based on wave superposition: a microphone picks up the noise, a processing circuit generates an inverted-phase wave, and the earbud’s speaker plays it to cancel part of the noise at the eardrum [3]. A design with an outer microphone is called feedforward, one with an inner microphone is called feedback, and many earbuds use both. Passive isolation such as enclosures, barriers or ear tips is inherently weak at low frequencies [3], so ANC fills exactly that gap. As a result ANC is most noticeable on steady, low-frequency noise such as engines, air conditioners and traffic. Voices and high-pitched sounds are mainly reduced by how well the ear tips seal.
ENC (Environmental Noise Cancellation) is a commercial term, not a technical standard. On the OH-T line, ENC is listed as call noise reduction: an algorithm processes the microphone signal to remove ambient noise on the speaker’s side. When listening to music you notice no difference from ENC, because it does not change the sound played by the speaker.
| Criterion | ANC | ENC |
|---|---|---|
| Goal | Reduce the noise the listener receives | Reduce the noise the other party hears during a call |
| Where it is processed | The audio path into the ear | The voice pickup path from the microphone |
| Who benefits | The person wearing the earbuds | The person on the other end of the line |
| Available on | OH-T102 | OH-T100, OH-T101, OH-T102 |
Table 1. ANC versus ENC. The “Available on” row follows the manufacturer’s published specifications.
4. How long a day can you listen with earbuds safely?
WHO–ITU and NIOSH reference levels
ITU-T Recommendation H.870, developed with WHO, sets the adult reference exposure at 1.6 Pa²·h over 7 days, equivalent to 80 dBA for 40 hours a week (75 dBA for sensitive groups such as children) [4][5]. Pa²·h is a unit of sound energy, so every time the listening level rises by 3 dB, the allowed time is halved. Applying that rule to the H.870 reference level gives Table 2.
| Listening level (dBA) | Maximum time per week | Average per day |
|---|---|---|
| 80 | 40 hours | about 5 h 43 min |
| 83 | 20 hours | about 2 h 51 min |
| 86 | 10 hours | about 1 h 26 min |
| 89 | 5 hours | about 43 min |
| 92 | 2.5 hours | about 21 min |
| 95 | 1.25 hours | about 11 min |
Table 2. Maximum listening time by sound level, calculated from the H.870 reference level of 80 dBA / 40 hours per week using the equal-energy principle (3 dB exchange rate). This is the author’s extrapolation, not a table from the standard.
For comparison, the occupational standard of NIOSH (United States, 1998) sets the recommended limit at 85 dBA for an 8-hour shift, also with a 3 dB exchange rate: at 88 dBA it drops to 4 hours, at 91 dBA to 2 hours, at 94 dBA to 1 hour [6]. For the same total of 40 hours per week, the WHO–ITU reference level (80 dBA) is 5 dB lower than the NIOSH occupational recommendation (85 dBA).
The reality of unsafe listening
The pooled analysis by Dillard and colleagues, covering people aged 12 to 34, found that 23.81% (95% confidence interval: 18.99–29.42%) listen unsafely on personal devices [7]. WHO also describes the scale of this risk in its “Making Listening Safe” programme [9].
Does ANC help lower the listening level?
In noisy places, listeners tend to raise the volume to drown out the noise. The study by Na and colleagues (2012) on 9 adults, with three noise environments of 65–70 dBA (traffic, conversation, high-speed train), measured the preferred listening level with ANC on and off [8]. The preferred level was lower with ANC on for all three earphone types:
- In-ear earphones: from 80.7 down to 78.2 dB SPL (−2.5 dB).
- Over-ear headphones: from 82.3 down to 79.7 dB SPL (−2.6 dB).
- On-ear headphones: from 86.5 down to 83.5 dB SPL (−3.0 dB).
A reduction of 2.5–3 dB corresponds to roughly 44–50% less sound energy. Under the 3 dB rule, a 2.5 dB reduction increases the allowed listening time by about 22.5/3 ≈ 1.8 times. This is an illustrative extrapolation, because the study measured in dB SPL inside the ear rather than dBA, and only 9 people took part. A sensible reading: ANC helps for real but modestly, and it does not turn a high listening level into a safe one. Noise-cancelling earbuds are not hearing protection equipment.
5. Is “20–24 hours” of battery life believable?
The OH-T102 specifications state a 30 mAh battery per earbud and a 300 mAh charging case, 4–5 hours of listening per charge (ANC on), and 20–24 hours in total with the case. Let us do a quick check on whether the numbers are consistent.
- Assume a nominal lithium battery voltage of 3.7 V: each earbud holds about 30 mAh × 3.7 V ≈ 111 mWh. Divided by 4–5 hours, the average consumption per earbud is about 22–28 mW.
- Ideally the 300 mAh case could fully recharge the two earbuds (2 × 30 mAh = 60 mAh) at most 5 times. With an assumed conversion efficiency of 70–85%, that falls to about 3.5–4.25 times.
- Adding the initial full charge in the earbuds: total time from (1 + 3.5) × 4 hours to (1 + 4.25) × 5 hours, about 18–26 hours.
The 18–26 hour range encloses the published 20–24 hours, so the specification is plausible in energy terms. But “20–24 hours” is a total that includes the recharges from the case, not continuous listening. Actual running time also depends on volume, whether ANC is on, and ambient temperature.
6. Which should you pick: OH-T100, OH-T101 or OH-T102?
| Product | Bluetooth | Noise cancelling | Per listening session | Total with case | Controls |
|---|---|---|---|---|---|
| OH-T100 | 5.4 | ENC for calls | 4–5 hours | 20–24 hours | Touch |
| OH-T101 | 5.4 | ENC | 4–5 hours | 20–24 hours | Touch |
| OH-T102 | 5.4 | ANC + ENC | 4–5 hours (ANC on) | 20–24 hours | Smart touch |
Table 3. Published specifications of three TWS earbud models. All three are compatible with iOS and Android, with a range of 10–15 m without obstacles.
A simple way to choose:
- Often on the bus or metro, or working in an open-plan office: choose the OH-T102. ANC has real value, and you can keep the volume lower.
- Mostly listening in quiet places and making calls: the OH-T100 or OH-T101 with ENC is enough, and you do not pay extra for a feature you will not use.
- Pay attention to fit. Both ANC and bass depend on the ear tips sealing the ear canal, so try different tip sizes before deciding that a noise-cancelling earbud performs badly.
None of the three models publishes a water-resistance rating or codec, so do not assume either.
7. How to read this article
- ANC helps you listen quieter, but the evidence is thin. The study we cite had just 9 participants, three simulated noise settings, and measured preferred volume rather than hearing effects [8]. Treat it as a positive sign, not a guarantee.
- Safe limits are averages. H.870 counts across a whole week, and every ear is different. If your ears ring after listening, that is your cue to turn it down and take a break.
- Table 2 and Section 5 are illustrations. We extrapolated from clearly stated assumptions to make the ideas concrete; they are not measurements of any specific earbuds.
- Full transparency. This article was written by OH-Tech and mentions our own products; every technical figure is cited so you can check it yourself.
8. Conclusion
Read the three numbers on the box again: the Bluetooth version does not measure sound quality, the codec decides it; ENC serves the person on the other end of the line, ANC serves the wearer; and a safe listening level is measured in both volume and time. ANC can help lower the listening level by a few decibels, but keeping the volume moderate remains the most important way to protect your hearing.
Frequently asked questions
How do ANC and ENC differ?
ANC reduces the noise you hear while wearing the earbuds, by playing an inverted-phase sound wave. ENC reduces the noise the other person hears when you make a call, using an algorithm that processes the microphone signal. In the OH-T line, only the OH-T102 has ANC; all three models have ENC.
Does Bluetooth 5.4 sound better than Bluetooth 5.0?
Not necessarily. What is new in Bluetooth 5.4 focuses on one-to-many data transmission and advertising security, not audio. Sound quality depends on the codec that both the phone and the earbuds support, and on the earbuds’ drivers and sound tuning.
How long a day is it safe to listen with earbuds?
According to the WHO–ITU H.870 reference level, an adult can listen at 80 dBA for 40 hours a week, about 5 hours 43 minutes a day. Every additional 3 dB halves the time; for example, 89 dBA leaves only about 43 minutes a day. Many phones have a listening-level tracker for headphones so you can check for yourself.
Do noise-cancelling earbuds protect your hearing?
Only indirectly. A small study found that listeners chose a level about 2.5–3 dB lower when ANC was on in a noisy environment. However, noise-cancelling earbuds are not hearing protection equipment, and they do not replace keeping the volume moderate.
How long does a TWS earbud battery last?
For the OH-T100, OH-T101 and OH-T102, the published figures are 4–5 hours of listening per full charge of the earbuds and 20–24 hours in total including the charging case. The case recharges the earbuds several times, but actual running time depends on volume and whether ANC is on.
Which earbud models does OH-Tech offer?
There are currently three models: the OH-T100, OH-T101 and OH-T102 (with ANC). Prices are by quotation; contact OH-Tech or a dealer for advice.
References
- Bluetooth SIG. What’s new in Bluetooth Core 5.4: An overview. bluetooth.com.
- Bluetooth SIG. Bluetooth LE Audio FAQs. bluetooth.com.
- Kuo, S. M., & Morgan, D. R. (1999). Active noise control: a tutorial review. Proceedings of the IEEE, 87(6). doi:10.1109/5.763310.
- ITU-T. (2022). Recommendation H.870 (V2, 03/2022): Guidelines for safe listening devices/systems. itu.int.
- World Health Organization & International Telecommunication Union. (2019). Safe listening devices and systems: a WHO-ITU standard. who.int.
- National Institute for Occupational Safety and Health. (1998). Criteria for a recommended standard: Occupational noise exposure, revised criteria 1998 (Publication No. 98-126). cdc.gov/niosh.
- Dillard, L. K., Arunda, M. O., Lopez-Perez, L., Martinez, R. X., Jiménez, L., & Chadha, S. (2022). Prevalence and global estimates of unsafe listening practices in adolescents and young adults: a systematic review and meta-analysis. BMJ Global Health, 7(11), e010501. doi:10.1136/bmjgh-2022-010501.
- Na, W. S., Kim, K. W., Jung, S. D., Lee, J. W., Jung, J. Y., & Suh, M. W. (2012). Effect of active noise cancelling earphones on preferred listening level when listening to portable music players in noisy environments. Korean Journal of Otorhinolaryngology–Head and Neck Surgery, 55(7), 415–421. kjorl.org.
- World Health Organization. Making listening safe. who.int.
