Research shows the success of a bacterial community depends on its shape.
What's it like to have little or no hearing for years and then suddenly get a lot of it back? In the space of four days, Michael Pierschalla went from perfect hearing to near-deafness more than 10 years ago; a hearing aid helped a little, although he also had to learn to read lips. He later lost his hearing entirely for five years until he got a cochlear implant in 1985. Then he re-encountered sound.
"I don't think my feet really touched the ground for the first couple of days," he recalled. "At first it was confusing. I had to take time to understand what I was listening to, and I was startled at the sound of my own voice. My first impression was, `Lord, what a noisy place this is.' There's so much to hear. Starting a car, washing dishes-everything that happens makes noise."
John Anderson relied on a hearing aid and lip-reading for most of his life until he became completely deaf in August 1982. After hooking up his cochlear implant three years later, "I was able to tell people not to shout any more," he said. Although he must still read lips to understand speech clearly, the implant has made many things more feasible, such as using the phone with people he knows, or taking classes (he is pursuing his master's degree in counseling psychology).
When Mr. Pierschalla was deaf, "I lived an 18th-century life," he said, noting that he didn't use many modern devices like a stereo, TV, radio or telephone. "I was one of the few in my generation to miss disco, punk, All Things Considered-things like that." With the implant, he could again listen to the latest music, some by artists whose sound had evolved while he was deaf. "I could really hear the change in Clapton's voice over the years," he said.
The quality of sound from a cochlear implant is not robotic or mechanical in quality, as some believe. "I wasn't prepared for it to be recognizable," he said. "It's like listening to an inexpensive radio with the station off-tuned a bit. You can hear regional accents and voice pitch, although you might miss every fifth or sixth word." Mr. Pierschalla was a furniture maker when he was deaf but he now works as a technician for a sound conservation program, testing the hearing of employees at noisy industrial sites and factories.
Implants are far from perfect; they provide less dynamic range than normal hearing, so background noise interferes more, and because only one ear is used, pinpointing the directional source of sounds can be difficult. Nevertheless, some implant recipients, even those with hearing that's still quite limited, keep their processors turned on all the time to maintain a connection to the world of sound. But Mr. Pierschalla occasionally turns his off and returns to being deaf. "It's nice to have the quiet and peace of your own thoughts," he said.
A version of this article appeared in MIT Tech Talk on May 10, 1995.