Technology

ROAD EQ

The ultimate natural-sounding acoustic correction,
even for the worst in-car noise.

Air conditioner noise, tire noise and wind noise are some of the many noise factors that contribute to a less than satisfactory in-car listening experience. These low-frequency, high-energy noises mask the in-car audio and can cancel out low-to-mid frequencies in the music—the very frequency range that gives music much of its depth, naturalness and vibrancy. In the past, efforts have been made to resolve the problems caused by in-car noise through technologies like ANC (Active Noise Control) that attempt to reduce audible noise by emitting phase-inverted noise from a speaker, as well as features like Automatic Volume Control and Automatic Loudness Control that automatically regulate the volume played depending on the noise level.

However, the effectiveness of these solutions is limited. Deficiencies of the Automatic Volume Control and Automatic Loudness Control methods include the lack of theoretical support for the correction algorithms used, unsuitability for

auditory sensation (mainly because corrections are carried out by sensing low-frequency vibrations under 20Hz and vehicle speed), and their inability to monitor changes in the noise level.

Alpine’s RoadEQ is an innovative noise-reduction system, and the result of many years of development efforts. Using psychoacoustic theory, accurate measurement of noise levels has been made possible all the way up to the 10kHz range, and the system’s tracking speed was accelerated to 20ms—the threshold for the human ear to detect volume and frequency. The powerful DSP uses a 24-bit processor to measure and correct the sound at a rate of 48,000 times per second. The result is optimal, real-time equalization and volume control for ever-changing noise. The unique logic to differentiate noise and carry out optimal audio correction, fine-tuned from over 50,000km of road tests, allows for extremely natural and transparent correction. With RoadEQ, a completely stable volume and sound quality is guaranteed even in fast-changing conditions.