In research to create comfortable sound, Sound Design Lab LLC and the Takeshi Toi Laboratory at Chuo University are advancing with a project to make engine sound more comfortable. Until now, engine sound was perceived as noise, but this research team has discovered that engine sound actually resembles the tonal characteristics of stringed instruments.
“Electric and hybrid vehicles are gaining popularity, but these types of cars don’t generate any engine sound. There are concerns that they may be dangerous to others who can’t hear them coming. The best solution would be if a person could hear the sound of the engine and immediately recognize about how fast the car is traveling and from which direction. The only way to create comfortable engine sound is to examine all of those sounds and determine what types actually sound like an engine but are comfortable.”
In tests, the research team used several instruments to represent good sound and analyzed vehicle engine sounds, acoustic pressures, and frequencies. Next, test participants listened to 5 types of vehicle engine sounds and the tones of instruments, and subjective and objective assessments were conducted to analyze sound quality. The subjective assessment looked at psychological effects, while the objective assessment considered indicators such as changes in heart rate, changes in saliva amylase, and changes in the blood flow in the brain. As a result, the researchers found that engine sound and the tonal characteristics of stringed instruments are similar. They also learned that the tonal sound of imported luxury sports cars is particularly close to that of a violin.
“We think that the sounds of a musical instrument and an engine are vastly different. But a physical analysis of those sounds shows that the waveform created by a musical instrument contains sound components that are higher than the harmonic sounds. Such characteristics make the engine and the musical instrument sound similar. Our latest test showed that when someone hears these sounds and perceives these types of characteristics, they recognize that the sounds are very similar.”
Sound Design Lab and the Toi Lab will examine the impact that engine sounds have on the human body and will advance with research and development to make the sounds of industrial products more comfortable.