| 摘要 |
PURPOSE:To improve the comfortable feeling in an acoustic sense by detecting the rotational frequency of an engine, generating various frequencies which are even fold number as much as said rotation to convert them into acoustic outputs and varying the output level in proportion to the noise level in a vehicle. CONSTITUTION:The rotational frequency of the revolution of the engine 2, for example, sixteen fold number of the rotation, is detected in a detecting part 3 and wave-shaped 31. Next, it is divided in a dividing circuit 32 to obtain the even fold harmonic waves which are sixteen, eight, four and double fold number of the revolution of the engine and converted into sine waves in a sine wave conversion circuit 40, then after the amplitudes are adjusted 45' and mixed 45 they are inputted in a sound volume control part 51. And also to the sound volume control part 51, the opening signal of a throttle 4 is inputted after being counted and the output of a mixing circuit 45 is adjusted according to the opening of the throttle. The outputs from the sound volume control part 51 and an acoustic system 5 for a vehicle are mixed and amplified in a power amplifier 52 to drive a speaker 10. Thus, the signal having even fold number as much as the revolution of the engine, which does not make a man uncomfortable, is composed in a proper amplitude ratio, so that the comfortable feeling in the acoustic sense can be improved. |
