A Day with Gerhard Hofstetter – Engine Sound Designer at BMW M
He seems to soak up the noise, letting it fow through him like some kind of meditation exercise. The 43-year-old Hofstetter is an engine sounds designer at BMW M GmbH. His job is to give engines a more refined tone, teaching them the language of BMW – or more specifically, the distinctive dialect of a BMW M.
“Every M model creates an unmistakable soundscape,” says Hofstetter. “A distinctive sound is as important for an engine as its output. Sportiness, speed and power – they all have to be heard, even at a standstill.” Earlier that morning the acoustic expert picked up the car at the BMW Aschheim testing facility near Munich.
In this soundproof environment, high-tech microphones register everything from the swish of the air intake system and the chorus of cylinders to the final harmonious boom of the twin exhausts. At both idling speed and full throttle revs, computers record every sound and display the frequencies on a color monitor, like the spectroscopic analysis of light. The frequencies are the acoustic fingerprints that are unique to each engine.
They can, however, be manipulated. Hofstetter’s job is to turn basic sounds into music. Every cavity in the exhaust system is a potential sound amplifier or moderator. Frequencies can be modulated by altering pipe lengths; desired pitches can be amplified by reflectors; harsh dissonances, muffled by acoustic wool.
Although the engine may growl, it must not sneeze; it can whisper, but not whistle; sound throaty, but not cough. An M engine should have power, not asthma.
As Gerhard Hofstetter puts it, “The engine sound should make the driver’s spine tingle and the hair on the back of his neck stand up.”
This game of patience requires great sensitivity. Adjusting the sound of an engine is like tuning a musical instrument – except can take months to get an engine sound just right. After studying the latest measurements Hofstetter takes the car on the test track for a lunchtime spin.
No amount of measuring and analysis can do the job as efficiently at the human ear. He wears a headset with integrated microphones to record ever sound nuance with absolute fidelity.
Later in the afternoon, Hofstetter plays the recordings of the future engine tunes for some colleagues. The rasping undertone of the cold start is gone. Each touch of the accelerator now shatters the silence with a fanfare of trumpets. Perfection. “A BMW M is a highly emotional product.
Every engine has its own unique sound, and that has to exactly fit that particular car model,” the sound designer explains. “An M6 is quite different from an M5, although both are powered by the same 10-cylinder engine Acoustically, the M6 Coupe is closer to a racecar than the M5 Sedan.”
By now it is late afternoon. Time to go home. Hofstetter takes his foot of f the accelerator and the key out of the ignition . He is a man with a passion for his work. His office houses an archive documenting the sound of every M model ever produced. In his free time he is an avid racecar enthusiast even the ring tone of his mobile phone is the roar of a BMW Sauber F1 racer. Tomorrow, Hofstetter presents his lates composition of engine sounds to another group of specialists. He’s bound to have another hit.
Source: BMW Magazine