Operating system: Windows Phone 8.1
SIM card type: Nano SIM
Screen: 5 '' (TrueColor 24 bit / 16 million, 16: 9, ClearBlack, OLED, Corning Gorilla 3 Glass)
Resolution: 1920x1080 Full HD, Pixel Density: 441 pixels / inch
Battery: Non-removable (2420mAh)
Processor: Qualcomm Snapdragon в„ў 800, Four cores 2.2 Hz
Description of the processor.
RAM: 2GB
Storage: 32GB
Rear camera: 20 megapixels, PureView
Front camera: 1280 x 960 pixels
Camera flash type: Dual LED flash
WiFi: WiFi 802.11 a / b / g / n / ac
NFC: have
Bluetooth: Bluetooth 4.0
LTE frequencies: 1, 3, 7, 8, 20
WCDMA network: 850 MHz, 900 MHz, 1900 MHz, 2100 MHz
GSM network: 850 MHz, 900 MHz, 1800 MHz, 1900 MHz
Wireless charging: Built-in (Qi standard)
Type of memory card: no
GPS system features: Positioning based on information from Wi-Fi and cellular networks, A-GPS, A-GLONASS, BeiDou, Sensor, enhanced positioning
Dimensions: length: 137 mm, width: 71 mm, thickness: 9.8 mm, weight: 167 g

1. Does the screen's blueness (purple hue) hinder you:
but. Yes - 14.05%
b. No - 37.58%
at. And what is this, difficult to answer, or not critical - 48.73%
2. Have you encountered the problem of screen relegation in the upper right corner of the frame
but. Yes - 25.42%
b. No - 74.58%
Number of people surveyed 354
3. Do you have interruptions when playing music via Bluetooth connection
but. Yes - 12.56%
b. No - 24.64%
at. I do not use this function - 62.8%

Location:
The first is the main front microphone bottom (On a soft loop)
Second - Rear Bottom (On soft loop) (Noise reduction and stereo sound in video)
The third is the front upper speaker (On the motherboard) (Handsfree, Any Voice Assistant, Shazam, and TP)
Fourth - Rear Top (On the motherboard) (NoisePressures and Stereo sound in video)

Testing can be carried out lumia test application

On 8.1:
The MC camera writes mono, removes sound from the front upper microphone.
Lumia Camera writes stereo. Two modes:
- Stereo - takes the sound from the rear microphones, front - to suppress the sound from the side of the receiver.
- Surround sound (Surround Sound aka Dolby 5.1) - writes from all 4 microphones.
The recording volume should be checked not by ear, but on a computer in some audio editor, for exampleAVS Audio Editor