“I See Something You Only Hear”
Every noise and every sound give our environment its distinctive quality. Take a car for instance: its horn warns, the CD player soothes, the click of its blinkers informs and flapping windshield wipers annoy. Bosch researchers are using an acoustic camera to quickly and precisely locate the sources of noise and make them visible for further examination.
Our sense of hearing has a mind of its own. It simply can’t ignore a disturbing noise. The noise is just there, and it’s unnerving. But where exactly is it coming from?
That is not a simple question to answer. After all, our sense of hearing can be easily led astray when it tries to locate the source of a disturbance. Researchers and developers at Bosch are taking a deeper look into the question: Just what does the mechanism of noise production look like? How does sound propagate during its journey from its point of origin to the human ear? In the process, researchers have to keep one particular point in mind: It does little good to observe the acoustics of the individual components. The entire system is the critical factor, because acoustic behavior varies dramatically depending on whether a component has been welded, riveted or glued.
Bosch researchers, in their efforts to react flexibly and quickly to every question and customer request, are using a new type of acoustic camera that reliably pinpoints sources of sound. The result of their work, whose motto could be “I see something you only hear,” is images of sounds and noises.
The acoustic part of the equipment looks something like a hula-hoop. Thirty-two sensitive microphones are attached to this ring, and a video camera is located in its center, from where it records a picture sequence while a sound recording is being made. On a computer screen, a distribution of the sounds’ intensity is superimposed on the film. At the headquarters of Bosch research in Gerlingen, Germany, the process is described with a smile: “A ventriloquist’s secret would be revealed right away.” But this camera doesn’t do its act on a stage. Instead, it goes to work in an anechoic chamber, where it hears and tracks the unfiltered operating noises of such things as drills, angle grinders and windshield wipers.
One of the problems with windshield wipers, for instance, is finding a source of noise when they are rapidly moving back and forth: Is it the wiper edges, their mounts or their gears? Only the acoustic camera can give researchers a precise picture of the cause.
That is not a simple question to answer. After all, our sense of hearing can be easily led astray when it tries to locate the source of a disturbance. Researchers and developers at Bosch are taking a deeper look into the question: Just what does the mechanism of noise production look like? How does sound propagate during its journey from its point of origin to the human ear? In the process, researchers have to keep one particular point in mind: It does little good to observe the acoustics of the individual components. The entire system is the critical factor, because acoustic behavior varies dramatically depending on whether a component has been welded, riveted or glued.
Bosch researchers, in their efforts to react flexibly and quickly to every question and customer request, are using a new type of acoustic camera that reliably pinpoints sources of sound. The result of their work, whose motto could be “I see something you only hear,” is images of sounds and noises.
The acoustic part of the equipment looks something like a hula-hoop. Thirty-two sensitive microphones are attached to this ring, and a video camera is located in its center, from where it records a picture sequence while a sound recording is being made. On a computer screen, a distribution of the sounds’ intensity is superimposed on the film. At the headquarters of Bosch research in Gerlingen, Germany, the process is described with a smile: “A ventriloquist’s secret would be revealed right away.” But this camera doesn’t do its act on a stage. Instead, it goes to work in an anechoic chamber, where it hears and tracks the unfiltered operating noises of such things as drills, angle grinders and windshield wipers.
One of the problems with windshield wipers, for instance, is finding a source of noise when they are rapidly moving back and forth: Is it the wiper edges, their mounts or their gears? Only the acoustic camera can give researchers a precise picture of the cause.
Researchers use an acoustic camera (in the foreground) to visualize the sound emitted by a windshield-wiper system.
