[Three minutes of small science] What did we do when calling when making a call?
In addition to listening to music, headphones are the most popular. A lot of true wireless headphones on the product promotion page, in addition to focusing on the noise reduction capacity and sound quality of their own headphones, it will emphasize how the call effect of their own headphones. The problem of throwing the signal, on the headset, no matter how good the sound quality, the sound will become very poor during the call, and many times when you can't even know what the other party said. Do you know what things do you do when calling? What is the factor affecting the quality of the headset call? What is the effort to do the headset manufacturer in call? I will answer one by one.
When you wear an earphone, first, the microphone on the headphones converts the sound analog signal into a digital signal. After encoding on the headset, the mobile phone receives the audio signal file from the headset to send it again. When the other party is answering the phone, the phone receives the audio file, and then send it to the headset, and the headphone is decoded and then sounds through the speaker. You can talk to the other side of your mobile phone through this. This is one of the key factors of the Bluetooth connection using the headset and the mobile phone is one of the key factors of the call quality.
We all know that the current headphones are connected to Bluetooth. However, according to the specification developed by the Bluetooth Technology Alliance, Bluetooth This connection is in fact, and there is a lot of different agreements, and different agreements have different scenarios and needs. For example, when we listen to music, use Bluetooth A2DP (Advanced Audio Distribution Profile) protocol. The A2DP protocol is specifically set to transmit music. Its advantage is that the code rate is large when the transmission is transmitted, ensuring the quality of the sound, but the disadvantage is relatively high. The HSP (HEAD-SET-PROFILE) protocol is used when making a call. This protocol is specifically used to implement telephone communication. The advantage of HSP is that the delay is relatively small, but the code rate of audio transmission is low, which is to ensure the need to be higher than the quality of sound quality when the call is required. Therefore, when the true wireless headset is on the call, it is limited to the transmission limit of the current Bluetooth technology. The sound of the call will have a lot of distortion.
However, Bluetooth is only one of the factors that affect the sound quality of the call. The microphone and call dowdyisurable algorithm on the headset can also affect the quality of the call.
Call noise reduction
The environment is sometimes complicated when making a call. For example, in the subway, in the mall, the microphone should handle both vocals and environmental noise at the same time. At this time, I really test the design capabilities of headset manufacturers for headset microphones, as well as call noise reduction. The most common call noise reduction plan in the true wireless market is dual wheat beamforming technology. When the two microphones are judged, the time difference of the voice is received, and the direction of the voice is judged. Then filter out the noise reduction algorithm inside the headset and only retains the vocal portion to achieve call noise reduction. This technology almost became the standard function of true wireless headphones, although it is dodeca noise reduction, but the noise reduction algorithm has different, which looks at which noise reduction chip and adjustment of the earphone manufacturer.
龙 畅 超 超 宽 语 语 APTX Voice
softwareIn terms of Qualcomm launched the Snapdragon Sound dragon listening platform, which contains the HFP (HANDS-Free-Profile protocol "APTX Voice 龙 龙畅 技 技术. Aptx Voice allows headphones to identify audio speech and distinguish noise. This can significantly improve the problem of human distortion and restoration degree during the call. Summary is to improve the code rate of headphones transmission when the call is improved and filtering the vocals through a better algorithm. Many Android phones have supported this feature. Some headset manufacturers have followed this feature. After all, this technology needs to support both mobile phones and headphones.