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Soundcore Liberty 4 in the test: Anker's headphones measure the heart rate in the ear

Mar 14, 2023

Long said to be the AirPods Pro 2, the Soundcore Liberty 4 now bring a heart rate sensor for the ear that delivers surprisingly good readings. The other extras are also lavish with LDAC, multipoint, wearer detection and wireless charging. When it comes to the sound, however, Soundcore turns the tuning control a little too much.

Table of contents

Technical data and functions of the Liberty 4
1. Two drivers, spatial audio and heart rate measurement via ear
2. LDAC and Multipoint
3. Slide charging case
4. Up to 28 hours of battery life
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Protected against sweat and splash water
Controls with automatic pause
1. Customize the controls in the app
2. Hassle-free single use
Extensive Soundcore app
Very comfortable fit
The sound of the Soundcore Liberty 4
Analysis of the frequency response

< li>ANC of the Liberty 4

Good transparency mode
Heavily filtered telephony
Latency of the Liberty 4
Conclusion

With the Soundcore Liberty 4, Anker brings LDAC in-ears with heart rate measurement and dual drivers. What has been said about the Apple AirPods Pro for years now anchors the Soundcore series. So the company not only promises a very good sound, such as that offered by the Liberty 3 Pro (test), but also good value for money in addition to the novelty. Because the suggested retail price of the Soundcore Liberty 4, which is available in black or white, is 150 euros, so it's in the middle price range.

In addition to the earphones, buyers also get a charging case , four different sized earbuds, a USB-A to USB-C charging cable and a quick start guide.

Technical data and functions of the Liberty 4

Two drivers, Spatial audio and heart rate monitoring by ear

Like the Liberty 3 Pro, the Liberty 4 rely on sound via two drivers per earphone, with Anker speaking of two dynamic drivers this time, while the Liberty 3 Pro combines a dynamic driver with a balanced armature driver. This makes the highs clearer.

The Liberty 4 offer a virtual 3D sound via head tracking. This spatial audio also works in conjunction with LDAC, but not if the individual sound adjustment via HearID Sound or an equalizer is used. The position sensor in the ear can also be used to warn you if you keep your head tilted downwards, i.e. if you have assumed a harmful posture. After calibrating to a neutral, straight position, the in-ears will then play a warning tone if your head is down for five minutes.

They also have health tracking for the first time and record the heart rate of the wearer. For this purpose, an optical heart rate sensor is installed in the ear piece of the right earphone, which continuously records the heart rate when wearing the in-ear headphones. The current heart rate and its progression over time can be called up via the Soundcore app. In addition to the minimum and maximum heart rate, the average heart rate is also displayed. In order to be able to use this function, the right earphone must therefore be worn. The measurement is also performed when no music is played. In the test, it proved to be surprisingly accurate. In everyday life, the difference to the measurement with an Apple Watch 8 is usually a maximum of 1 to 2 beats per minute, so it can be neglected. Both a low and a high heart rate are recorded well by the Liberty 4.

With this function, the Soundcore Liberty 4 does not replace a smartwatch that you wear on your wrist all day and continuously records your heart rate. The heart rate measurement function is primarily useful for getting started if you don't have a smartwatch or don't want to wear it during training. Otherwise, the monitoring via the sensor in the ear is usually too incomplete for monitoring the heart rate, since data is usually only collected for a few hours at a time, but then there are long breaks in the diagrams.

LDAC and Multipoint

In addition to SBC and AAC, the Liberty 4 support the Hi-Res audio codec LDAC with up to 990 kbit/s, 24 bit and 96 kHz sampling as well as an extended frequency response from 20 to 40,000 Hz. Bluetooth 5.3 is used as the radio standard . However, LE Audio, which would be possible from Bluetooth 5.2 and would replace SBC with LC3, is not represented. Bluetooth multipoint is also supported, so that the Liberty 4 can connect to two end devices at the same time and the playback can be seamlessly switched between them at any time. However, multipoint cannot be used in conjunction with LDAC, so you may have to make a decision here.

Anker installed a total of six microphones in the Liberty 4 for the ANC and telephony.

Sliding loading case

The dr Liberty 4 charging case measures 58.7 × 29.0 × 56.45 mm (W × H × D) and can be charged either via the USB-C port on the back or wirelessly according to the Qi standard using a charging pad. The example is not one of the smallest representatives, but its round shape makes it easy to carry with you in everyday life. Anker again relies on a cover that you can slide open and doesn't open. The earphones are easy to remove. To showcase the new heart rate sensor feature, Anker placed small LEDs in the charging case that light up the transparent ear tips when you slide open the lid. But they also have the practical function of indicating the approximate charge level of the earphones by flashing. An LED strip on the outer edge of the case does the same when charging the charging case.

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The charging case alone weighs 43 g. Each earphone is pleasantly light at 6 g.

Up to 28 hours of battery life

According to Anker, the battery life is up to nine hours per charge. The charging case adds another 19 hours for a total of up to 28 hours of music playback without a power outlet.

In practice, this results in around 7:25 hours of music playback without ANC and with heart rate measurement at medium volume and a colorful music mix. With ANC, heart rate measurement and using LDAC, however, it is only enough for 5:45 hours. Not bad for what is on offer, but a good bit away from the advertised 9 hours without ANC or 7 hours with ANC. Thanks to fast charging, music can be played for almost 3 hours after 15 minutes of charging.

Anker Soundcore Liberty 4 Huawei FreeBuds 5i Bose QuietComfort EarBuds II Apple AirPods Pro Samsung Galaxy Buds 2 Pro Bluetooth standard: 5.3 5.2 5.3 5.0 5.3 Audio codecs: SBC, AAC, LDAC SBC, AAC SBC, AAC, SSC Operation: Key Touch Battery life the earphone: 9.0/7.0 (ANC) h7.5/6.0 (ANC) h6.0/6.0 (ANC) h5.0/4.5 (ANC) h8.0 /5.0 (ANC) h Battery life with charging case: 28.0 h 24.0 h 29.0 h Wireless charging: Yes – Yes ANC: Yes Single use: Yes IP certification: IPX4 IP54 IPX4 IPX7 Weight per earphone/charging case only : 6.0/43.0g 4.9/33.9g 6.3/60.0g 5.5/46.0g 5.5/43.4g USB Charge Port: USB-C Lightning USB -C Dimensions charging case: 29.0 × 58.7 × 56.5mm 48.2 × 61.8 × 26.9mm 66.3 × 59.4 × 26.7mm 45.2 × 60.6 × 21 .7 mm 50.1 × 50.2 × 27.7 mm Price: from €149 €99.99 from €249 from €239 from €155

Protected against sweat and splash water

The earphones are protected against water according to IPX4 protects. Rain and sweat during training cannot harm them. However, the earbuds may not be submerged for cleaning or worn while swimming.

Control with automatic pause

The control of the Liberty 4 is based on that of the AirPods Pro. To operate, the handle of the earphones is taken between the thumb and forefinger and gently pressed. The amount of pressure required to trigger a function can be set in the app to prevent unwanted operation.

A single press starts and pauses playback, while a double press toggles between the sound modes, i.e. ANC, Transparency and Normal. Whether you want to switch between all or just individual modes can be set in the app. If only one earphone is used, a single press also serves to start and pause playback, but a double press skips one track forward. Pressing three times skips back one track (left) or one track forward (right).

The Anker Soundcore Liberty 4 also have a function to automatically pause playback when a earphone is removed from the ear. The wearer detection sensor works reliably. The function can also be calibrated again and switched off in the Soundcore app, if desired.

Adjusting the volume is therefore initially not possible ex works.

Adjusting the controls in the app

However, Anker's Soundcore app allows you to adjust the assignment. Single, double and triple presses can be reassigned for each earbud and the following functions are available: volume + and -, next, previous, play/pause, Siri (on iOS), ambient noise and “None”. . Functions such as “volume +” can be assigned independently of their counterpart, so that six independent functions can actually be configured.

The sound effects can be toggled between spatial audio, HearID sound, standard and a custom equalizer. The equalizer again offers either presets for adjusting the sound or the option of making individual adjustments in eight bands between 100 Hz and 12.8 kHz, which can also be saved.

The spatial audio, in which the earphones change their sound relative to the position of the playback device, also works reliably in everyday use. When using the in-ears, it seems as if the sound is always coming from the tablet in front of you, even if you turn your head to the side.

In addition to the now obligatory firmware updates, the app also offers an overview of the battery status of the individual earphones and a fit test. In this case, music is briefly played in a quiet environment and it is checked how much leaks out. Options for automatic shutdown and for the aforementioned dual connection (multipoint) can also be found in the settings. As mentioned, the latter costs support for LDAC.

Very pleasant seat

The in-ear headphones from Anker sit very comfortably in the ear and exert almost no pressure. They can be worn for hours without any problems – an important point if you actually want to use them to record your heart rate over a longer period of time. At the same time, they sit so firmly in the ear that they don't fall out when jogging.

The sound of the Soundcore Liberty 4

The Soundcore Liberty 4 deliver a good sound that is largely convincing even without adjustment, but sounds a bit too harsh in the highs and too dull in the mids. It's the highs again, so to speak, but this time the anchors not only cause some problems at high volume and start to hiss and sound a bit harsh. The mids are separated well, voices are clear and understandable. However, the emphasis on the mids already shows that the bass in particular is emphasized, whereas the mids can hardly assert themselves and fall off a bit too much. That sounds modern and delivers a voluminous bass foundation that can develop a lot of pressure. With very soft tones, however, the deep bass in St Jude by Florence + The Machine disappears too early and can no longer be made out.

With the equalizer and HearID you can definitely improve the sound of the Liberty 4 and you should give both options a chance if the standard sound seems a bit too dull and you prefer to hear more neutral tones.

If you want an even better sound, you can find it at a higher price with the Sennheiser Momentum True Wireless 2 (test), the Sony WF-1000XM4 (test) and the Bose QuietComfort Earbuds II. Also the commercially available Samsung Galaxy Buds 2 Pro (test) are slightly ahead in terms of sound.

Frequency response analysis

ComputerBase also carries out frequency response measurements for the wireless in-ear headphones. For this, the miniDSP Headphone & Earphone Audio Response System (H.E.A.R.S.) in connection with the software REW. This is not an IEEE standardized measuring station. However, it provides good comparative values, which in particular enable the headphones under consideration to be compared with one another. The microphones in the right and left ear of the miniDSP H.E.A.R.S. are calibrated. Since the miniDSP H.E.A.R.S. no inner ear modeled, but has a straight auditory canal, the measurements alone are not a sufficient criterion for a final assessment of the sound, but can only be seen as supplements to the descriptions. Clarity and dynamics cannot be rated either.

The sound pressure of all headphones is calibrated at around 84 dB at 300 Hz – not all in-ears can be set to exactly 84 dB here, so that a deviation of 1 dB up and down has to be accepted. All measurements are carried out according to the manufacturer's specifications from 20 Hz to 20 kHz several times and with different earphone positions in order to take these influences into account and to detect a bad fit. In the case of in-ears, this quickly becomes apparent in strong outliers, an unclean frequency response or a complete lack of bass with poor sealing. The results are averaged and smoothed from five measurements per side with the best established fit. A straight line at 84 dB would correspond to a neutral presentation of the frequencies, which is never achieved in reality.

The frequency analysis of the Anker Soundcore Liberty 4 shows that they are not neutrally tuned in almost any area. The bass is a little less bulky in places than the Liberty 3 Pro, but they go a step further in the deep bass and treble and distort it even more. The small range of the tonally neutral mids cannot counteract this and the described sound losses occur.

ANC of the Liberty 4

The Liberty 4's ANC filters deep sounds well without disturbing you with a loud background noise even in quiet surroundings. The background noise is hardly perceptible and not disturbing with both adaptive and manual setting of the ANCs at the highest level. This shows once again that even ambient noises in particular are very effectively dampened, while sudden, unforeseen sound events are filtered out much better by models such as the Bose QuietComfort Earbuds II.

Typing on the keyboard or clicking the mouse remain as bright noises due to the strong attenuation of low frequencies and can therefore still be heard clearly when using ANC. Depending on the environment, it can be more pleasant to manually turn the ANC back to “Medium” to let more noise through, but to soften the strong focus on high frequencies.

The ANC of the Liberty 4 is also susceptible to wind due to the external microphones. Wind noise reduction mode brings some relief, but also reduces ANC performance at the same time.

Good transparency mode

With the Trabnsparenz mode, users can choose between two modes: full transparency and voice mode. While the first transmits all noises unhindered to the wearer's ear, the second primarily amplifies voices.

Overall, the transparency mode has a pleasant sound, as it does not block the environment in particular renders hard. However, if you use it without playing music or with podcasts, the audible background noise is a tad too loud.

Heavily filtered telephony

When it comes to telephony, the Soundcore Liberty 4 picks up where the Liberty 3 Pro left off. Ambient noise is heavily filtered, ensuring only the occasional bird chirp is transmitted while road noise is completely eliminated. This also leads to a somewhat tinny, distorted sound of the voice on the Liberty 4, which is, however, transmitted clearly and loudly.

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