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The conventional active noise control technology for engine booming noise1 based on the Filtered-Reference LMS algorithm 2,3 has a conflict in between the ability of tracking a change of engine rpm and simultaneously controlling the low frequency (low rpm) region. As a result, the conventional approach is difficult to apply for booming noise for a low rotation engine, an important region for weight reduction of a vehicle. Because of these reasons, there are few applications of the conventional approach to reduce booming noise. The purpose of this study is to propose a less complex ANC system based on a Single-frequency Adaptive Notch (SAN) 2,4 algorithm. The system proposed in this paper solves the problem of good control performance in the low rotation or rpm region, assures the stability related to a mass production, and reduces the number of component parts in a manufacturing process.

With conventional automotive systems overall music sound quality depends on whether car is running or not. It is so because the low frequency component of the sound is masked by the road noise when running. To develop a system in which the sound is not easily masked by the road noise, we have paid attention to the difference between the speaker velocity changes (acceleration characteristics) due to the road noise and those of the music signal, and to the attack transient which is important to identify the timbre. The rise time response of the loudspeaker is a key factor for improvement, and conventional speakers have limitations in this regard. In 1995 the authors presented the New-AFB System1) in the SAE convention, which explained the technology and advantages of acoustic feedback in achieving flat sound pressure vs. frequency and enabling substantial improvement in response time of the speaker. Since then we have applied this to develop an optimum system for automobile use.

The C&C (Computers & Communications) society is coming which helps activities regarding human knowledge and information by means of communication networks with plural computers interconnected. The C&C society inevitably includes mobile bodies. And the actual form for cars is defined as the “Car and C&C”. The relationship between the need for the “Car and C&C” and the “fixed system C&C” is discussed. Actually the technical possibility for realizing the “Car and C&C” depends on the mobile communications technology and some measures overcoming the communication capacity problem are discussed. The system configuration of the “Car and C&C” is shown including the items needed for both the car system and the fixed system. A few examples of their applications are also described.

This paper describes the efforts that have been made in the pursuit of high volumetric efficiency, high thermal efficiency, and high mechanical efficiency in the Honda small high-speed gasoline engine. The problems discussed include utilization of the dynamic effects of intake and exhaust systems; combustion characteristics; concrete measures to reduce mechanical loss; and valve floating, which poses difficult problems in realizing high-speed four-stroke engine operation.