NEC Develops Wind Noise Suppression Technology that Ensures High Quality Phone Signals and Audio Recordings Even in Strong Wind- Technology that flexibly responds to the strength and characteristics of wind -

*** For immediate use May 7, 2013



Tokyo, May 7, 2013 - NEC Corporation (NEC; TSE: 6701) has developed a technology that suppresses wind noise for mobile phone calls, video recordings and similar activities conducted outdoors, while maintaining natural sound. This technology helps enable phone conversations and video recordings to take place with clear sound by suppressing wind noise that interferes with desired signals such as speech.

With the spread of smartphones and other such devices, phone calls are now made in a wide range of different environments. This has drawn greater attention to the problem of wind noise, which makes voices difficult to hear when  mobile phones are used in windy places, such as near high-rise buildings or alongside rivers. Furthermore, wind noise also causes interference when mixed with the audio track of video recordings.

A conventional solution to this problem is to suppress microphone signals in the frequency ranges where wind noise is concentrated. However, this method has some drawbacks. For example, it suppresses not only the noise, but all the desired sound in the frequency range, resulting in unnatural sound. Conversely, wind noise is not sufficiently suppressed when soft suppression is applied.

NEC’s new technology divides wind noise into two elements; (1) noise generated by wind at a constant level (stationary noise) and (2) quickly changing noise whose level depends on wind strength (non-stationary noise). The new technology then suppresses each element of wind noise as appropriate. It is the world's first(*1) technology that responds flexibly to the characteristics and strength of wind in order to exclusively eliminate wind noise. Application of this technology helps to ensure high quality voice signals for phone calls and video recordings even in windy conditions.

An evaluation of this technology implemented in an Android™ terminal confirmed that the technology suppresses only wind noise and maintains natural sound even on a smart device with limited computing power.

The technology can be applied widely to communication and recording devices used outdoors, including mobile phones, video cameras, digital cameras and voice recorders.

Features of the new technology are as follows.

1. Ensures effective wind noise suppression of stationary and non-stationary noise
   This technology divides wind noise into a stable component (stationary wind noise) and a quickly changing component whose level fluctuates depending on wind strength (non-stationary wind noise). It estimates the power of stationary wind noise and that of non-stationary wind noise, then eliminates these estimated wind-noise components from the input signal.
   
   As a result, the technology ensures smooth phone conversations and natural audio in video recordings by effectively suppressing only wind noise while maintaining high quality signals.



2. Simultaneously suppresses ambient and wind noise with approximately 30% less computation
   The technology suppresses both ambient and wind noise by sharing the same process for the decomposition and reconstruction of input signals. This enables approximately 30% less computation compared with the conventional method that suppresses the two types of noise in a cascade form. As a result, it causes no significant delay in the suppression process even on smart devices with limited computing power.

Note

(*1) According to NEC research