HOME > CX-NEWS  > CX-NEWS Vol.53 > Side View

Integrating Sony's Audio, Electronic Circuit, and Software Technologies The World's First Digital Noise Canceling Function   Noise canceling headphones reduce ambient noise such as the low rumbling of the engine in an airplane cabin or subway train and provide a quiet listening environment. Sony has now succeeded, for the first time in the industry, in creating a digital implementation of the signal processing that forms the core of that functionality. What has changed due to this digital implementation? This article investigates this question and introduces Sony's headphone technology. Introduced at CES International this January Digital noise canceling headphones “MDR-NC500D” Main features ● The industry's first digital implementation of a noise cancellation function*1, and reduction of ambient noise by approximately 99%*2 ● Sony's AI noise canceling function, which analyzes the ambient noise and automatically selects the optimal noise reduction mode ● Inclusion of a digital equalizer that applies compensation to the playback signal using digital signal processing and creates superb audio quality with realism *1: According to Sony's research as of March 2008 *2: When comparing not wearing headphones in the Sony stipulated simulated airplane environment to using noise canceling mode A. A total noise suppression of 20 dB (using Sony's test methods) corresponds to a 99% noise reduction in audio energy. DSP Technology has Caught up with Audio Technology

. . Why had this product not been implemented in digital yet? Noise cancellation cancels noise by analyzing the ambient noise and generating a reverse phase (inverted waveform) sound. (See figure 1.) The important point here is how quickly and correctly this phase inversion can be performed. For performing these calculations, previous DSPs were unable to exhibit a clear superiority over analog processing. Furthermore, their power consumption was excessive for portable equipment. The situation has, however, changed. In the context of technological advances such as the increasing functionality of cellular phones, Sony's device technology has evolved rapidly. Equipment in which audio and DSP technologies collaborate has matured. Then, two years ago, we formed a team consisting of audio design, electronic circuit design, and software design engineers and started a full-scale development effort towards digital noise canceling headphones.

Implementation is Possible Because it is Digital

See all articles with figures and tables.

Vol.53

	HOME | Site Map | Information | CX-NEWS