Researchers have created three compact speaker system designs that control the direction of sound more efficiently than previous models. The scientists were able to manipulate the timing and strength of the outgoing sound waves for each speaker. They created an array of speakers and took advantage of the constructive and destructive interference of sound waves.
As the size of electronic devices decreases, so must the size of their component parts, such as speakers. Researchers from Northwestern Polytechnical University in China and the University of Quebec published three designs for compact speaker systems that control the direction of sound more efficiently than previous models in JASA Express Letters, a journal published by the Acoustical Society of America.
Single speakers send out sound waves in all directions. However, for an effective loudspeaker system, sound must be focused in one direction, much like a flashlight beam in a dark room. The directivity factor compares the amount of sound released in the desired direction to the amount of sound released in other wasted directions.
Researchers developed three designs for compact speaker systems that control the direction of sound more efficiently than previous models.
“We want the beam to have the highest directivity factor possible,” author Jingdong Chen explained. “Or, to put it another way, we want the beam to be sharp enough that we can only direct the energy in certain directions.”
The scientists were able to manipulate the timing and strength of the outgoing sound waves for each individual speaker. They created an array of speakers and took advantage of the constructive and destructive interference of sound waves.
Sound waves canceled each other out in unwanted directions while efficiently carrying sound energy in the desired direction. The directivity factor in speaker system designs was increased as a result of this.
The team discovered that the higher the directivity factor, the more speakers they combined in the array. “This is something we want, but we have to pay a price for it,” Chen explained. “We need to expand the array by using more loudspeakers.” To avoid sound distortion, the speaker arrays must perform equally well at all frequencies.
The authors optimized various aspects of the speakers in their three system designs. The first achieves the desired sound wave direction very well, but at low efficiency. The second maximizes efficiency, but the array does not perform consistently across all frequencies, resulting in sound distortion. The final design is efficient and consistent, but it may have a lower directivity factor than the previous two.
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