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OKI Develops Area Sound Enhancement System to Pick up only Sounds in a Target Area

Achieves brilliantly clear sounds in targeted areas for smooth communication in video conferencing and noisy conditions

TOKYO, April 15, 2015 -- OKI (TOKYO:6703) today announced that OKI has developed a technology called Area Sound Enhancement System that makes it possible to pick up sounds in a target area by positioning several directional microphones. The technology lets users hear speakers' voices in a specified area, even in acoustically cluttered environments in which several people are talking at the same time, like conference rooms or offices.

Comparison to existing technologies

  • 【Ordinary microphones】
    Ambient noise, including other voices, makes it difficult to catch what the speakers are talking.

  • 【OKI's Area Sound Enhancement System】
    Catch the speakers' voices clearly even under noisy conditions.

In recent years, with the continuing developing of ICT, video conferencing and telework have become increasingly familiar, which has continued to expand opportunities to communicate with people in remote environments. In environments in which speakers' voices overlap with other voices and ambient noise and difficulties of hearing the speakers' voices may interfere with smooth communication. In order to solve this problem, a technology that can accurately pick up only sounds in a target area is required. Using directional microphones such as shotgun microphones and microphone arrays(*1) can pick up sounds in specific directions, but these microphones pick up not only sounds in a target area but noises in the same direction as well because the directionality extends linearly.

The Area Sound Enhancement System developed by OKI uses two microphone arrays, and crosses each directionality of arrays from different directions in a target area. A common component in all directionalities of arrays is estimated to be a target sound, and then other components are suppressed as noises. This makes it possible to pick up only sounds in the target area and ensures clear speakers' voices for video conferencing and other remote communication in noisy environments. The technology also allows the speakers to talk while shifting their positions and walking about, as long as they remain within the area covered by the microphone arrays.

Features of OKI's Area Enhancement System

  • Pick up only voices in the target area, even when many people are talking out of the area.
  • Require a microphone array consisting of as few as two microphones.
  • Generate modest calculation requirements, allowing users to pick up sounds in multiple areas at the same time in real-time working.
  • Let speakers move about while talking, as long as they remain within the area covered by the microphone array.
  • The "area sound activity detection" function makes it possible to pick sounds only at the time sounds are generated in the target area.

Examples of applications

The system has wide applications beyond video conferencing, telework, and other modes of remote communication. Some examples are given below:

  • Hands-free conversations without an echo and a howling
  • Preprocessing for improved speech recognition rates (car navigation systems, devices for taking the meeting minutes automatically)
  • Picking up sounds in noisy environments (at exhibition sites, plants, ticket handling machines at railway stations)
  • Use in areas where privacy and security are critical (banks, contact centers)

Examples of applications

Moving forward, OKI will seek to enhance and leverage the Area Sound Enhancement System for application across a wide range of scenarios.

Component technologies contributing to the Area Sound Enhancement System include the research and development of ultra-realistic communications technologies by the innovative 3D imagery, part of an array of development projects entrusted by the National Institute of Information and Communications Technology (NICT).

Overview of OKI's Area Sound Enhancement System

OKI's Area Sound Enhancement System arranges two microphone arrays around a target area and forms the directionality on each array to the target area by beamformer(*2). Under these conditions, sounds in the directionality of an array are typically mixed with the target sound and noises (Left, Figure 1). However, the nature of voice that components of each voice rarely overlap in the frequency domain allows target sounds to be distinguished from surrounding noises. Two microphone arrays' directionalities in the frequency domain are focused on the targeted area and therefore the target sound components are commonly included, while noise components differ from in each microphone array (Right, Figure 1). Leveraging this characteristic, the target sound components are estimated to be the common components included in each microphone array's directionality. The target sounds can be enhanced by suppressing other components as noises (Figure 2).

Figure 1. Directionality of microphone array

Figure 2. Area Sound Enhancement processing


  • *1 :Microphone array

    It consists of several omnidirectional microphones, and forms directionality by signal processing.

  • *2 :Beamformer

    It forms directionality by taking advantage of time delay to each microphone.

About OKI Electric Industry (OKI)

Founded in 1881, OKI Electric Industry is Japan's leading telecommunications manufacturer in the Info-telecom field. Headquartered in Tokyo, Japan, OKI provides top-quality products, technologies, and solutions to customers through its info-telecom systems and printer operations. Its various business divisions function synergistically to bring to market exciting new products and technologies that meet a wide range of customer needs in various sectors. Visit OKI's global website at http://www.oki.com/.

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  • * Information in the press releases is current on the date of the press announcement, but is subject to change without prior notice.

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