Bass and directionality

"The bass has no direction." Therefore, "the bass and subwoofer can be placed anywhere on the floor of the room (listening room)."

This is an ancient sound law, so old that no one would question it. For many years, masters have said this, and they have been published in special issues, and they have said so in the forum. It should be said that before the boom of home theater, a single subwoofer, even if it is an enthusiast, rarely had it. The term "direction" has little to do with everyone. With the rapid development of home theater or IT industry in more than ten years, especially the application of some advanced technologies, the subwoofer has become an indispensable pillar and characteristic part. The relationship of "direction" is extraordinary.

 Although the housing area of the general public has been significantly expanded in recent years, many people have a single room in a home theater or game hall, but there is still a wide range of small and incomplete environments. A question of satisfaction. The pioneer of air-cushioned speakers, American AR company, a few years ago with genius creativity, used the method of installing large-caliber woofers on the lower side of the speakers to subtly reduce the volume of the speakers and ensure the special bass shock required by home theaters. The effect has promoted a new trend of thin and tall speakers with large woofers suitable for the general public space. Speaker manufacturers at home and abroad have imitated or re-developed them, and suddenly developed into an inherent style of home theater speakers. Compared with the history, the independent boxed subwoofers are "longer" and conform to the surging tide of home theater. Of course, the multimedia active speakers are not ineffective, and they are already the two major ones of AV and IT. Factions, and vigorously penetrate into the HiFi field of pure music. Under such a premise and situation, it should be necessary to discuss the directionality of bass and subwoofer, as well as the placement of speakers.

 As we all know, stereo is developed based on the human binaural effect. When people use two ears to listen to sound together, they can improve their ability to locate the sound direction. This kind of listening effect is called binaural effect. People can use one ear to determine the loudness, pitch, timbre, and every attribute of the sound except for direction, but a single ear can only distinguish the direction of the sound source to a certain extent, and cannot specifically determine the direction and exact location of the sound source. When the other ear is added, because the sound waves from a certain sound source travel to the two ears at different distances, the time for the sound to reach the two ears is not the same, resulting in differences in time, phase, and intensity. The positioning of the two ears is based on the time difference, phase difference and intensity difference between the two ears. At the same time, the ability of the human ear to distinguish the direction of the sound source varies with the frequency of the sound. Since the distance between the two ears is about 16~18cm, which is half of the 800-1000Hz sound wave wavelength, there will be no sense of direction for sounds lower than or equal to this frequency. It can be seen that, in the general sense of bass or super bass, there is no directivity. Especially the bass system used as a multimedia audio system for computer playback, it can also place the subwoofer according to local conditions. It is no big problem to adapt it to the environment and space. A large-diameter bass is installed inside the AR, and various types of subwoofers that are independent into a box are the intimate equipment introduced to solve the contradiction between the space and appreciation of Yunyun users.

However, it should also be noted that sound sources have certain radiation directivity. Low-frequency sound waves have a longer wavelength. Although the radiation directivity is not as obvious as high-frequency sound waves, it is not completely absent. This is a problem for pure music HiFi enthusiasts, especially those with a high fever. The first is that the two basses placed on the inner side are placed opposite each other, which will affect the correct radiation directivity, and make the sound become muddy and hysteretic. A single box of subwoofers, if it does not form a horizontal axis with the main speaker, will have different sounding directions. Radiation and the unreasonable time difference between reaching the listening ear will also affect the localization and quality of the sound. Based on this, the author always believes that as long as there are conditions, the speakers with internal woofers should be placed in two positions. The subwoofers are placed on the same axis as the main speakers. HiFi friends should pay more attention to this point. It will be used. The bass still has to be more directional.