The traditional production concept for car engine sound has changed from finding a solution to unwanted noise, to designing a particular sound. Although many studies have investigated the development of comfortable car-engine sounds, the psychoacoustic effects of time-varying rate for accelerating engine sounds remain unclear. Thus, we investigated the effects of increasing the frequency of interior car noise on auditory impressions, using psychological and neurophysiological methods. We carried out two investigations. First, we examined the relationship between the impression of 'sportiness' from the dynamic characteristics of the engine sound and brain magnetic fields. Complex harmonic tones simulating acceleration noise were used as stimuli, and subjective evaluations were examined using the semantic differential method. Neuronal activity in the auditory cortex was measured using magnetoencephalography (MEG). Second, we examined the relationship between subjective preference and brain magnetic fields for the simulated interior noise of an accelerating car. Subjective evaluations were examined using a paired-comparison method. The MEG alpha-wave range (8-13Hz) was measured and analyzed using the autocorrelation function. Neuronal activity was longer following stimulation by a preferred sound. Our results indicated that the particular characteristics of engine sounds have a significant effect on subjective impressions and neuronal activity in the auditory cortex.
2013 The Society of Instrument and Control Engineers