It’s the laws of physics. Bigger microphones and headphones sound better. A full-size headset picks up your voice clearly while rejecting background noise, and reproduces your voice’s full frequency range. In contrast, miniaturized devices such as hearing aids and “hands free” earsets pick up background noise louder than they pick up your voice, and reproduce only the high-frequency overtones of your voice, missing your fundmental frequencies of phonation.
Stuttering is an inability to control vocal fold vibration, or phonation. Effective stuttering treatments start with vocal fold awareness and control. Delayed auditory feedback (DAF) helps stutterers to hear their phonation, if the device is capable of picking up and reproducing phonation frequencies. Adult men’s vocal folds vibrate around 125 Hz; women are around 200 Hz; and children are even higher. Hearing aids reproduce sound in the 2500-5000 Hz range, far above anyone but a mouse’s phonation.
The studies finding DAF to be effective used full-size microphones and headphones. Studies of DAF hearing aids found little or no effect. Pitch-shifting, also called frequency-altered auditory feedback (FAF), lowers your voice in your headphones typically a half-octave, which for men goes below 100 Hz. You need high quality headphones to reach these frequencies.
Over time Casa Futura Technologies DAF devices become more effective, training more than 50% carryover fluency after the devices are removed. DAF devices made by other companies lose what little effectiveness they started with over time.
The carryover effect means that you can start talking with the headset, and then take it off and continue to talk fluently. Headsets are easily slipped on and off, giving you a fluency boost when you need it while training you to not become dependent on the device.
Headsets also help you to disclose stuttering. At the start of a conversation I say that I stutter and that I’m going to use my anti-stuttering device. Listeners are curious and ask what the device does. I hand the headset to the listener and explain that the device can be adjusted to make stutterers fluent, or to make fluent people stutter. I ask if the person wants to try stuttering. Everyone says yes, and I “crank up” the DAF to 200 ms. The person then finds him- or herself stumbling over and repeating sounds and words.
At parties this soon attracts attention and everyone wants to try the device. After everyone has tried it there’s always someone who tells me that his or her cousin or friend stutters, and wants my advice.
We’ve sold hundreds of DAF devices to school districts for disability awareness days. Few other disabilities that can be switched on and off so easily and so, well, surprisingly.
I’ve answered hundreds, maybe thousands, of calls that start with, “I want to buy an anti-stuttering device but do you have one that’s tiny and invisible?” We then have a conversation about developing fluent speech over time and disclosing that one is a stutterer. If you try to hide stuttering, you’ll stutter for the rest of your life. If you talk to people about your stuttering, and practice effective, evidence-based treatments, your speech will improve over time.