Whether in the era of feature phones or smartphones, music phones have been positioned by many manufacturers to attract some users who like to listen to music. The recently released Find5, as always, inherits the genes of OPPO music phones and adopts the new Dirac HD? and Dolby Mobile Sound 3.0 technologies. Dirac HD, Dolby sound effects... these words are often used by businesses as promotional selling points. I believe everyone is familiar with these words, but do you really understand them? Let’s talk briefly about Dolby sound first. Dolby Pro Logic is a surround sound system developed by the American Dolby Company. It synthesizes four-channel stereo sound into two channels through specific encoding methods during recording, that is, the original left channel (L), right channel (R), center channel (C), surround channel ( S) are encoded and synthesized into LT and RT composite two-channel signals. During playback, the encoded two-channel composite signals LT and RT are restored to the encoded left, right, center and surround signals through the decoder. Four independent signals that are independent of each other are amplified and input into the left speaker, right speaker, center speaker and surround speaker respectively. Because of this characteristic, Dolby is often used in movie theaters and home theaters, and it only improves stereo sound and does not improve the sound quality itself. And Dirac HD Sound, that is, Dirac HD, really improves the sound quality on the sound source. Dirac HD Sound is an advanced patented technology developed by the Swedish company Dirac Research AB. It can compensate the speaker system through digital processing. By correcting the transient response and frequency amplitude response of the sound system, it can make headphones or speakers Achieve high-fidelity performance. The first is to correct the transient response of the sound system: due to the nonlinear characteristics of the speaker system itself, the transient response will change. The importance of the transient response of a loudspeaker system is one of the key factors in the fidelity of a system. The figure below compares the response time and amplitude changes during the attenuation time of a speaker system when playing a transient response signal before and after Dirac HD Sound processing: Compare the test results, for the same transient signal, the original system starts from It takes a long time for the vibration of the unit to stop from the moment the system begins to receive the instantaneous signal until the playback is completed. And if another sound signal collides with the previous transient signal, it will obviously be transients at two different time points. The signals are mixed together, which results in a loss of fidelity during sound reproduction. After Dirac processing, the playback of the signal can be completed instantly and the unit stops in time. Dirac HD Sound's compensation technology can effectively improve the above problems, and the sound quality can be significantly improved through the compensated transient response characteristics. In fact, to put it bluntly, it is to remove some impurity sounds and filter the sound to make the sound clean and pure, thereby making the sound quality better. The second step is to correct the frequency amplitude response of the sound: the frequency amplitude response is related to the playback volume ratio of various musical elements, and is also an important factor in system fidelity. We often say that the treble is harsh, the bass is roaring, and the midrange is too much. In fact, it means that the frequency amplitude response of the speaker is poor and the volume of the original signal is not accurately restored. Dirac HD Sound technology uses a unique hybrid phase technology. Compared with traditional equalization processing, it improves the frequency amplitude response of the system more reasonably and effectively, and corrects the frequency amplitude response characteristics of the speaker with near-perfect high precision. Therefore, we The original appearance of the sound can be heard. From the above diagram, we can see that the Dirac-corrected speaker amplitude response can accurately match the target curve, thereby accurately restoring the true volume of the original music signal. The upper part of the picture above is the measured frequency amplitude response of the speaker before optimization, and the lower part is the measured response after optimization by Dirac HD Sound technology. The black one is the target curve we hope to achieve. OPPO started using Dirac HD Sound on its series of mobile phones in 2012.