By Dr. Maureen Hunter
The phone not taken
Maybe mom's mobile device isnt so dumb after all.
"MOM," MY SON SAYS HIS VOICE TINNY THROUGH THE PHONE SPEAKER. "YOU NEED TO GET A SMARTPHONE."
Sitting in the passenger seat of my car, my daughter driving with the insecurity inherent in student drivers, I adjust my grip on what I affectionately refer to as my “dumbphone.” It’s a Samsung flip phone. Part of the reason I have little desire to part with it is that we’ve been together for a long time.
“I’m sorry, Chris, I can’t hear you,” I tell my son, aware of how juvenile it sounds. In the driver’s seat, my daughter raises an eyebrow at me, yelps when the car swerves, and locks her eyes with the road again.
“Why? Are you going through a tunnel?”
“No.” I take a moment to admire the way sunlight dapples the road, filtered by the foliage above. “I can’t hear you because you’re a man.” The expectant silence on the other end of the phone prompts me to continue. “My phone’s speaker only transmits frequencies from 350 to 4000 Hz. Your voice is at 100 Hz, more or less. ”
My daughter pulls to a sharp stop at a red light. “Then how do phone speakers work at all?” she asks. “I mean, obviously we can hear Chris’s voice.”
“Our ears perform a Fourier Transform,” I say, speaking now for both my son’s and my daughter’s benefit. “The fundamental frequencies of men’s voices are around 100 Hz. Some are a little higher, some a little lower. But every note produces frequencies that are integer multiples of that fundamental frequency.”
“Alright.” Chris clears his throat. “So let’s say my voice is 120 Hz. It also has overtones at 240 Hz and 360 Hz and so on and so forth, and the higher frequencies fall into your phone speaker’s range, and that’s why you actually can hear me.”
“Exactly,” I say. “It’s an auditory illusion. Luckily, ears are good at math and do that Fourier Transform and send the spectrum to the brain. And because brains are amazing pattern-recognition machines, they choose the whole pattern that best matches the frequencies transmitted by my phone. Our brains fill in the missing lower frequencies, and we hear the low tone of Chris’s voice.”
My daughter frowns a little. At my questioning, she says, “Wait. Multiples of the fundamental frequency of his voice? But wouldn’t that mean that he has overtones at every frequency? I mean, I can multiply 120 Hz by an infinite number of, well, numbers. And if I can do that, then I get an infinite number of frequencies.”
“Integer multiples,” I emphasize. “The fundamental frequency of a voice only has overtones that are integer multiples.” Knowing she isn’t much of a math person, I add for her benefit, “Whole numbers above zero.”
“Okay,” she replies, apparently satisfied.
My son speaks up. “You know, this is just another reason you need to get a smartphone.”
“Well, not really,” I say. “This is true for all phone speakers, regardless of make or model. Smartphones, dumbphones—all of them.”
“Really.” His tone implies that he’s about to say something he finds incredibly clever. “I’m gonna Google this on my phone just to be sure. Maybe you should do the same.”
“You know I can’t.”
“Maybe you should get a smartphone, then,” my son laughs. He promptly hangs up, and I feel a little as if I lost that verbal spar.
“It’s okay, Mom,” my daughter says. We’ve finally reached our driveway, and her hands scuttle along the steering wheel awkwardly. “I get it. I mean, your dumbphone isn’t completely lame. That thing always snaps back together when dropped, and let’s face it, who’d steal a dumbphone anyway?”
“Thank you, Laura,” I concede, content to place my dumbphone back into the car cup holder for an off-the-grid evening.
Perhaps I’ll get a smartphone someday. Just not today.
Maureen Hunter is the technical service manager for King Industries, Inc. in Norwalk, Conn.
You can reach him at email@example.com.
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