vivo NEX S Review: Call Quality


NEX S has eliminated the notch with a unique lifting camera structure, becoming a unique full-screen mobile phone. This high-end mobile phone is also hot in the summer of the World Cup. This 4498 yuan mobile phone, regardless of the online store or offline entity sales are already in short supply. The NEX S also has good competitiveness in terms of sound quality and screen, but in the end, the smartphone also has to make a phone call, and does the board less handset without the aperture have the quality of the video call?

NEX S, in addition to lifting the camera outside, hide sensitive component and the handset also done a lot of effort. Xiaomi found that the effect of the backward vibration sound is not good, or rationally opened a knife at the top of the screen of MIX 2s. NEX is not unique. The speaker with a plane vibration is close to the OLED panel, and the OLED panel is driven by the vibration of the speaker sound to solve the problem of the sound directivity of the earpiece. However, this wonderful design is not necessarily good. First of all, although the OLED is thin enough, it still loses a lot of volume through a layer of screen glass. In addition, this design cannot be used on a thick IPS panel screen. In addition, the conventional recording mode test is not applicable to such a sounding mode and will be explained in a later test.

NEX S is equipped with Qualcomm Snapdragon 845 processor. The baseband theory supports the highest downlink speed of Cat.16. It also supports MIMO multi-carrier aggregation and 4G+. It supports dual card dual standby. The flagship version is better than the cheaper version of NEX [SD710 version] The processor supports a more comprehensive network type, but one FDD-LTE 13 band is missing. NEX S runs Funtouch OS based on Android 8.1, so it supports Bluetooth HD audio encoders such as SBC, AptX HD, AAC and LDAC, but requires the Bluetooth headset itself to support the corresponding protocol for normal use. According tothe convention, the objective test of voice calls is still completed by China Mobile 4G LTE and China Unicom GSM.

Earpiece Speaker Test

Because the NEX's under-display earpiece is a surface source, and the front has no openings to isolate direct airflow, it is not suitable for the way Soomal typically uses to measure the volume of the earpiece [many microphones are extremely insensitive to such sources]. In actual use, the maximum volume of the NEX S's handset output is equivalent to -12 to -14dB level, depending on the distance between the ear and the screen when the user is talking. Although it does not match the handset volume of many conventional design phones, normal call volume is guaranteed. If the screen is attached to the ear, the volume improvement will be more obvious.

Loud Speaker Test

Speaker test was undertaken indoors with ambient noise level at 40dB or less, we turn up the ringtone volume to its maximum, and then use a sound level meter to measure sound level at the distance of one meter from the phone.

Testing Item NEX S OnePlus 6 Galaxy S9 Huawei P20 Pro vivo X21 iPhone X
Face Up,dB 78.0 74.1 74.3 76.8 77.7 78.5
Face Down,dB 79.5 74.2 75.4 74.6 78.2 78.6
In Camera Bag,dB 73.3 69.2 69.4 69.6 72.0 72.2

The NEX S's loud speaker volume is excellent, slightly better than X21 and Xplay6, and the ringing penetrating power is better. It is also easier to hear the ringtone in the pocket or bags. But it's the same monophony as Xplay6, and there's no stereo effect when playing games and videos.

Noise Reduction Test

We place this phone indoors with ambient noise level at 32db or less, in the middle of the room, we use a human-like structure "handholding" the phone to send voice signal, and put surround speakers in a certain distance playing 5 kinds of simulating ambient noise at 6db SNR. Then we standardize the recording from this end, and run a specific program comparing this recording with raw speech recording and noise-speech mixed recording to get noise reduction level, SNR improvement and SNRI-to-NPLR difference quantitative result.

Testing Item[Hand Holding] Noisy Crowd Background Music Pink Noise Roadside Voice
Total Noise Level Reduction,dB[Higher is Better] 46.5 45.1 48.2 44.5 39.4
SNR Improvement,dB[Higher is Better] 34.2 31.5 40.2 36.8 22.3
SNRI-to-NPLR difference,dB[-4 to 3] -4.4 -1.6 -4.2 -5.3 -0.7
Testing Item[Hand-Free] Noisy Crowd Background Music Pink Noise Roadside Voice
Total Noise Level Reduction,dB[Higher is Better] 46.3 45.2 46.6 46.7 37.1
SNR Improvement,dB[Higher is Better] 37.0 33.6 32.8 31.4 21.7
SNRI-to-NPLR difference,dB[-4 to 3] -3.0 -0.7 -8.1 -7.3 0.3
  • Total Noise Level Reduction, TNLR: Total Noise Level Reduction illustrates the reduction of ambient noise level. The average level is above 5dB. Theoretically, higher TNLR would be better, but an over high result may be caused by severe attenuation of voice signal, or interruption caused by poor phone signal or noise reduction algorithm flaw.
    Signal-to-Noise Ratio Improvement, SNRI: capability of an NS method to enhance the speech component of a noisy speech signal from an additive background noise. SNR improves after noise reduction by comparing noise-reduced and raw voice signal. Generally, the improvement is over 4dB.
    SNRI-to-NPLR difference, DSN: the signal level difference between raw and noise-reduced. Noise reduction process would attenuate voice signal level, cell phones would gain signal to ensure the call quality. Theoretically, it would be best that signal level remain the same before and after noise reduction. A standard signal level peak is -2.5dB. If the signal was gained too high, overflow would happen, and that means frequent crackle, too low, voice signal strength would not be enough, and that means the sound would be too low, and the other end would not hear clearly.
    The result is just a test reference under similiar circumstances or conditions, third-party websites or official technical data cannot be used for comparison.

In the handheld call mode of NEX S, in addition to the background vocal noise reduction effect is not thorough enough, the continuous noise environment such as music and road surface is filtered relatively clean, while VoIP and VoLTE have basic GSM calls under high sampling rate voice. the same. In the hands-free mode, the NEX S performs more generally in the noise reduction under continuous noise. In a car hands-free environment, it is necessary to maximize the voice of the voice to ensure that the listener can hear it.

Overall, the NEX S's call performance is a normal level of high-end mobile phones in vivo, except for the new technology that causes the volume to be slightly lower. The volume and sound quality of the earpiece may still have some room for improvement, and the dynamic performance of the whole mid-high frequency of the flat speaker is really better, but the sampling rate of the GSM call is usually low, and it cannot be played. It can only be felt in the HD call application such as WeChat and Skype.

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