Abstract: The invention relates to the technical field of synthesis of a heterocyclic compound, and particularly discloses a method for preparing 2,4-diaminopyrimidine oxide. The method includes the steps of: cyclizing 3-oxopropionitrile with guanidine under an oxidizing condition to obtain 2,4-diaminopyrimidine oxide, wherein the 3-oxopropionitrile is obtained by oxidizing 3-hydroxypropionitrile, which is a cheap and easily available pharmaceutical chemical, as a raw material. The method of the present invention is green and mild, realizing the synthesis of Aminexil from a simple, cheap and easily available raw material.

Abstract: The present application discloses an anti-wind noise earphone device. The anti-wind noise earphone device includes a shell, a first pickup hole and a second pickup hole, the first pickup hole and the second pickup hole being provided in the same side of the shell, the first pickup hole communicating with the second pickup hole via a channel, the channel communicating with a microphone. According to the present application, the first pickup hole and the second pickup hole communicate with each other via the channel, so as to channel and eliminate wind noise energy and achieve the purpose of eliminating wind noise, the structure is simple, and the effect of eliminating wind noise is obvious.

Abstract: The present invention discloses an open-ear hook-type wearable sound producing device, including a main body and an ear hook connected to the main body, wherein at least one speaker and at least one microphone are arranged in the main body; one side, facing a human ear, of the main body is provided with a forward vent; a distance between the orifice of the forward vent and an ear canal entrance point (EEP) is 0.1 to 50 mm; and a distance between a pickup end of the at least one microphone and the EEP is 0.5 to 10 mm. The structure and layout of the present invention are rational, which is helpful to improve noise cancellation performance and is suitable to wear for long listening sessions.

Abstract: A sound privacy protection device is provided, including: a wearable structure configured to be worn at an ear; and a mount structure connected to the wearable structure, where the mount structure is provided with at least one sound generating unit; the mount structure is provided with at least one front vent for guiding the sound generating unit; and an acoustic outlet end of the front vent is arranged close to an ear canal entrance point (EEP). According to the present invention, the front vent and the reverse vent are both arranged on the mount structure, and the front vent and the reverse vent are positioned at the set points through the wearable structure, such that the sound waves of the reverse vent and the front vent cancel each other out in the afar sound fields, thereby achieving the purpose of sound elimination, preventing the surroundings from hearing the sound emitted by the device and protecting privacy.