Sound Quality

A study found that a DAF/FAF anti-stuttering device made by my company was more than twice as effective as a DAF/FAF device made by another company.(25) The difference in effectiveness may have been due to differences in sound quality, e.g., listening to Beethoven played by a symphony orchestra isn't the same as hearing Beethoven as a cellphone ringtone.

Frequency Range

Different anti-stuttering devices have different frequency ranges. Generally, the bigger the microphone and earphones, the wider the frequency range.

My company's devices have a flat frequency response from 60 to 5000 Hz. This is the range of human voices, plus additional low range for FAF downshifting.

In contrast, hearing aids typically have a frequency range of 200 to 7000 Hz. The frequency ranges typically aren't flat, but instead are tuned to sound best somewhere between 3000 and 4000 Hz(26) (where most people lose their hearing). Hearing aids can't reproduce the low range of human voices, especially the fundamental frequency of phonation that's key to stuttering therapy.

Monaural vs. Binaural Sound

Binaural (two ears) sound is 25% more effective than monaural (one ear) sound.(27) My company's devices can be used either binaurally or monaurally. Other devices are monaural only.

Background Noise

Some anti-stuttering devices work well in quiet speech clinics, but are unusable in a noisy classroom or restaurant.

Noise-Canceling Microphones

Positioned correctly, a noise-canceling directional microphone eliminates background noise at the source. In contrast, the omnidirectional microphones in hearing aids, lapel microphones, and the smaller cellphone earsets pick up background noises louder than your voice.

Push-To-Talk Button

A "push to talk" button also eliminates background noise. You push a button and the device switches sound on. You let go of the button and the sound switches off.

In noisy environments you're usually in a group. For example, you go out to a restaurant with three friends. You talk one-fourth of the time. Most of the time you sit and listen, with clear hearing. When you have something to say, you push the button.

A push-to-talk button also works well for a child in school, who mostly listens and occasionally is called on by the teacher.

High-Frequency Filters

Most anti-stuttering devices have high-frequency filters to reduce noise above your vocal range.

Voice Activation

Voice activation switches on sound when the user talks, and switches off sound when the user stops talking. Voice activation works well if the device has a noise-canceling directional microphone. If the device has an omnidirectional microphone, loud noises switch on sound.

My company's Pocket Speech Lab analyzes your vocal fold tension and switches on DAF/FAF when you tense your vocal folds, before you stutter. It switches off sound when you're speaking with relaxed vocal folds, or not talking.

Dynamic Expansion

Some devices have dynamic expansion. This makes loud sounds louder and quiet sounds quieter. If you're using a noise-canceling directional microphone this makes your voice louder and background sounds quieter. With an omnidirectional microphone it can make your voice quieter and background noise louder.

Acoustical Transparency

Listening to someone talk, while you wear a DAF device that's picking up the other person's voice, is like reading the following:

That says, "difficult to hear another person speaking." You hear the person speaking twice, with the words out of sync.

In contrast, quarter-octave FAF pitch shifts have little impact on your hearing.(28) It's like hearing a tune played simultaneously on a violin and on a viola. This is called "acoustically transparent."

Hearing Safety

Some anti-stuttering devices occlude (block) the ear that the device is in. Some anti-stuttering devices pick up, distort, and amplify background noise. Either results in temporary hearing impairment while wearing the device. If a child can't hear his teacher, he'll fall behind in school. Or he might get hit by a bus that he didn't hear coming.

Permanent hearing damage is also a concern. Underwriters Laboratories tested one of my company's anti-stuttering devices and found that the maximum volume couldn't cause hearing damage. But regardless of what lab tests found, have your hearing tested before buying an anti-stuttering device. If you experience ringing in your ears or pain from loud noises (e.g., a siren going by), discontinue using the device and get your hearing retested.

Should Children Use Anti-Stuttering Devices?

Children under six shouldn't use anti-stuttering devices. Preschool stuttering therapy is usually 100% effective, so anti-stuttering devices are unnecessary.

Six- to thirteen-year-olds can use anti-stuttering devices under the supervision of a speech-language pathologist or a parent trained by a speech-language pathologist, or for limited unsupervised uses such as a classroom presentation. If your child gets speech therapy in school only twenty minutes each week, buying a device can enable your child to do therapy at home for thirty minutes every day, e.g., ten minutes reading aloud, a ten-minute conversation with a family member, and a ten-minute telephone call (perhaps to a grandparent).

We don't know whether children who stutter have the same neurological abnormalities that adult stutterers have. Altering a child's brain activity might cause his brain to develop in a different way. Extensive use of an anti-stuttering device might cause the child's brain to develop normal auditory processing and the child to outgrow stuttering. But perhaps extensive use of an anti-stuttering device would cause the child's brain to develop in another, unknown abnormal way. Until we know more about the brains of children who stutter, I suggest that children only use anti-stuttering devices if they want to, and the parents clearly hear improved fluency with on-target speech motor skills (e.g., relaxed vocal folds) when using the device.

Third-Party Payment

Most Americans who stutter can get anti-stuttering devices free.

Many states have special telephone equipment distribution programs that provide telephone-compatible anti-stuttering devices free to qualified residents. Some programs have income restrictions. These states include Arizona, California, Georgia, Maryland, Massachusetts, Missouri, North Carolina, Pennsylvania, Texas, and Wisconsin.

If you're unemployed, your state's vocational rehabilitation program will help you get a job, including paying for speech therapy and/or an anti-stuttering device.

In every case we know of, when a stutterer asked his or her employer for assistance paying for one of our devices, the employer was more than happy to help. Often the employer then offers the stutterer a promotion.

Many of our devices are paid for by health insurance. Speech clinics handle this billing. Casa Futura Technologies never directly bills health insurance plans.

We've had good experiences with service organizations including Sertoma (SERvice TO MAnkind) and Lions Clubs. Our experience has been that service organizations prefer to help low-income children and teenagers, and that they prefer to be approached by the child's speech-language pathologist.

We've also had devices paid for by Veterans Administration Medical Centers and Medicaid.

I'm not an expert on how foreign countries pay for health care. (In fact, I'm completely bewildered!)

For more about these and other programs, see my website

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