Sound processors cut cellphone bleeps from audio channels

January 31, 2014 // By Graham Prophet
Rohm has announced sound processors for volume and tone adjustment in audio devices, including car audio systems (BD37033FV, BD37034FV, BD37068FV) and AV receivers (BD34701KS2). In addition to the standard features, a special RF noise removal function is included, developed using proprietary analogue technologies, to minimise noise introduced in electrical equipment when receiving phone calls – by more than 10 times.

High quality sound sources and user expectations makes it important to minimise RF noise when receiving incoming calls. These products inherit the essential characteristics of existing systems, such as low noise and low distortion for high sound quality, as well as advanced switching in order to eliminate popping noise during volume and tone adjustment. New features include the first RF noise removal function for audio equipment that cuts noise generated by incoming phone calls, along with an audio leakage prevention function that activates when power supplies connected to an external amp are turned OFF. Sound leakage generated when power supplies attached to an external power amp are turned OFF is limited to only 1/30th the original level. Also, analogue techniques are used to eliminate noise in the low-frequency region that cannot be reproduced through simulation. Advanced switching operation minimises popping noises generated when adjusting the volume and/or tone for smooth, natural audio transition.

Rohm Semiconductor,