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Product Description

What Is MPiStutter?

MPiStutter is an app made by Casa Futura Technologies for Modifying Phonation Intervals (MPI) stuttering therapy. It analyzes the user's vocal fold activity and trains him or her to eliminate too-rapid speech elements and speak fluently at a normal speaking rate.

It can only be purchased through the iTunes App Store.

View a Video Tutorial



View in the Australian iTunes app store



In a study of MPI stuttering therapy , speech-language pathologists trained five adult stutterers to use MPI software running on a computer in a speech clinic. The stutterers then used the computer on their own, without SLP supervision. The subjects practiced 2-3 hours per day for 2-3 weeks. All five reached "near zero" stuttering on telephone calls to local businesses (a stressful speaking situation). Therapy was then discontinued. One year later all five subjects had maintained this fluency.

The National Institute for Deafness and Communication Disorders (NIDCD, part of the National Institutes of Health) is funding a six-year, $3 million study of MPI stuttering therapy. This is the largest study ever of a stuttering treatment.

Because MPI stuttering therapy can be done on a computer without the presence of a speech-language pathologist, the therapy is uniquely suited to mobile devices such as the iPhone. MPiStutter moves stuttering therapy out of the speech clinic and into situations of daily living.

The following screenshots show how MPiStutter measures the duration of phonation intervals. Phonation intervals are the periods of time your vocal folds vibrate to produce vowels and voiced consonants, delineated by voiceless consonants and pauses. A phonation interval 37 milliseconds long is shown below.


A phonation interval (37 ms duration)

The first screenshot (below) shows short phonation intervals (under 100 milliseconds) color-coded red, orange, or yellow. These short phonation intervals indicate stuttering or too-rapid speech that precedes stuttering.

Short red intervals indicate stuttering or rapid speech

Short red intervals indicate stuttering or rapid speech

The second screenshot (below) shows long phonation intervals color-coded blue or purple. These indicate fluent but abnormally slow speech, which characterize prolonged speech stuttering therapy (also known as fluency shaping or smooth speech).

Long blue intervals indicate abnormally slow speech

Long blue intervals indicate abnormally slow speech

The third screenshot (below) shows fluent speech at a normal speaking rate. The green phonation intervals show the user that his or her vocal folds are moving neither too fast nor too slow. Note that normal speech contains a some shorter (red) and some longer (blue) phonation intervals. Normal speech constantly changes speed, volume, and prosody (emotional inflection). As long the user produces a large percentage of green phonation intervals he or she will speak fluently and sound normal.

Green intervals indicate normal fluent speech

Green intervals indicate normal, fluent speech

MPI stuttering therapy can be done using only visual feedback (without earphones). But MPiStutter also provides auditory feedback so that the user can have a conversation without looking at the screen. Short (red) phonation intervals switch on the user's voice in earphones, delayed a fraction of a second (delayed auditory feedback or DAF). DAF induces slow, fluent speech in stutterers. When the user is speaking fluently at a normal or slow speaking rate (indicated by green or blue phonation intervals) the DAF switches off. As the user improves vocal fold awareness and control and increasingly speaks fluently the DAF switches on less and less often. When the user can speak fluently without the DAF switching on he or she can discontinue using MPiStutter.

MPiStutter is ideal for stutterers who have learned to speak fluently in a speech clinic but are having difficulty transferring this fluency to conversations outside the speech clinic.

The main window (screenshots above) shows the last four seconds of the user's speech. Above this a bar graph displays the last ten minutes of the user's speech. The goal is to make the green bars tall and the red, orange, and yellow bars short.

The Cumulative screen displays the total talk time for the day, percentage too-short intervals, and a bar graph displays daily totals for each duration of phonation intervals. The goal is to get 2-3 hours of talk time per day, while each day reducing the percentage of short intervals.

Cumulative screen

Cumulative screen

The Evaluation screen is used to evaluate the user's speech. The user reads a story and the app measures syllables per second and percentage too-short phonation intervals. The goal is to talk at a normal speaking rate with few short intervals.

Evaluation screen

Evaluation screen

 View in the Australian iTunes app store




MPiStutter runs on Apple's iPhone and iPod touch. The iPod touch is an iPhone without the cellphone functions, weighing only 3.5 ounces and costing $199 with no monthly contract. MPiStutter will run on the iPad as an iPhone app.

MPiStutter requires wearing a throat microphone to accurately monitor vocal fold activity. You can use MPiStutter with Apple's earphones and microphone (MB770G) if you tape the microphone against your throat using medical tape. Place your fingers on your throat and hum to feel your vocal fold vibrations. Tape the microphone to your throat where you feel your vocal fold vibrations best. Apple's earphones are binaural (two ears), which is 25% more effective than monaural (one ear) earphones. Apple's microphone doesn't reject background noise so only use this option in a quiet environment.

Apple earphones and microphone

Apple earphones and microphone

Another good option is the Iasus NT3 throat microphone. This throat microphone rejects background noise well and is popular with military personnel, law enforcement, and paintball enthusiasts (i.e., it looks cool).

Iasus throat microphone

Iasus throat microphone

The Iasus NT3 includes a monaural (one ear) earphone. The microphone can be hidden under a shirt with a collar. The earphone is the type used by television announcers; it's invisible to listeners in front of you. We sell two versions of the Iasus NT3 throat microphone: with the stock microphone; and with the microphone replaced with a medical accelerometer. The medical accelerometer detects vocal fold activity extremely accurately and completely rejects background noise.

Monaural sound is less effective than binaural sound. The Iasus NT3 throat microphone can also be used with binaural earphones. We recommend using earphones that don't block hearing such as Sony MDR-J10 or AirDrives earphones. To use an Iasus NT3 throat microphone with binaural earphones you will need an Iasus PC cable (type D) and a Headset Buddy 01-PC35-PH35 adapter.

AirDrives earphones

AirDrives earphones


It will also work with wireless Bluetooth accessories but the sound quality is not as good.


Connecting the Microphone and Earphones


MPiStutter with Iasus NT3 throat microphone and monaural (one ear) earphone


MPiStutter with Iasus NT3 throat microphone and binaural (two ears) earphones


MPiStutter with Iasus NT3 throat microphone, binaural (two ears) earphones, and headphones for speech therapist

Starting MPiStutter

Put on your throat microphone and earphones and start MPiStutter. The DAF is automatically switched on to help you adjust the microphone position. Start talking. When you hear your voice clearly click the "Ready" button.

Adjust the microphone gain so that the when you speak loudly the black line representing vocal volume comes close to the top of the main screen, and when you stop talking the black line drops to the bottom of the screen and the screen goes white.

Continue talking and you will see your phonation intervals color-coded:

  • Red, orange, and yellow indicate short phonation intervals.
  • Green indicates ideal phonation intervals.
  • Blue and purple indicate long phonation intervals.

7 Stages to Fluent Speech

Stage 0. Practice talking rapidly or stuttering to produce red phonation intervals.

If you can't do Stage 0: then you aren't stuttering with your vocal folds. I.e., b-b-bouncing with your lips, jaw, and tongue won't produce red phonation intervals. At the ASHA convention I hired a SLP student to help me demonstrate MPiStutter for three days. He wasn't a stutterer and he couldn't get red intervals on the screen. In his fluency class they'd learn "voluntary stuttering" and he knew how to b-b-bounce. MPiStutter showed him that b-b-bouncing isn't stuttering. On the third day he discovered that if he coughed he could get red intervals on the screen. I told him to talk while coughing. He tried and said that it's really hard to talk while coughing. I said, "Now you know what stuttering is."

Stage 1. Practice speaking slowly to produce all purple phonation intervals. Stretch your vowels until each syllable is a half-second or more long. Your speech will sound abnormally slow. Say one syllable at a time, with a pause between syllables, not between words. Hold each syllable equally. Many people mistakenly hold each word equally. E.g., at one half-second per syllable the phrase, "I am American" should take three seconds, not 1.5 seconds. I.e., this phrase sounds like "I am A-mer-i-can." Practice this until you are 100% fluent with all purple syllables.

If you can't do Stage 1: read our webpage about prolonged speech and watch our videos that are linked from that webpage, or see a speech-language pathologist who specializes in stuttering and practices prolonged speech, fluency shaping, or smooth speech stuttering therapy.

Stage 2. Continue to stretch each syllable and say each syllable separately, but shorten each syllable to a quarter of a second. Practice this until you can get a screen with only blue intervals, and you are 100% fluent.

If you can't do Stage 2: ask a comedian what the most important element of comedy is. Timing! Practice until you have better control of your syllable timing.

Stage 3. Say multi-syllable words normally, i.e., without pauses between syllables. Practice until you have all blue and purple phonation intervals, you are speaking at a "slow-normal" rate (i.e., a little slower than you usually talk but you sound normal), and you are 100% fluent. Relax your breathing and relax your vocal folds. You should hear your vocal volume and vocal pitch drop, i.e., the "sexy voice." In other words, in stages 1 and 2 you used the stretched syllable target, but in stage 3 you use two targets: stretched syllable and relaxed vocal folds.

If you can't do Stage 3: try "two-handed stuttering therapy". Put one hand one your stomach. Breathe so that your hand moves out when you inhale, and in when you exhale. Notice that you're taking many small breaths. Your inhale and exhale times are equal. This is relaxed or diaphragmatic breathing. Now place the fingers of your other hand on your throat. Exhale and hum. Your fingers should feel a vibration. This is your vocal folds vibrating. Stop humming, and feel the vibration stop. Practice switching your phonation on and off. Vary your phonation in two ways. Change your volume (hum louder, then quieter). Change your pitch. Hum up and down a musical scale. With one hand on your stomach and your other hand on your throat, feeling diaphragmatic breathing and phonation, you should talk fluently. Now go to YouTube and watch some Barry White music videos. Pick one of his sexiest lines and practice it until you sound sexy.

Stage 4. Now you are ready to try for green phonation intervals. Drop the stretched syllable target and talk at a normal speaking rate. (If you use stretched syllables you will not produce green intervals.) Use only the relaxed breathing and relaxed vocal folds targets. Say multi-syllable words normally, i.e., without pauses between syllables. You should start to see green intervals.

If you can't do Stage 4: relax your breathing and vocal folds and vary your speaking rate until you see green phonation intervals. Don't expect to see all green phonation intervals, the goal is to produce some green phonation intervals. Normal speech won't produce all green intervals. When you are speaking fluently at a normal speaking rate you will see a third or half green intervals, a third or quarter blue and purple intervals, and a third or quarter red, orange, and yellow intervals. In other words, normal speech produces a normal distribution or bell curve of phonation interval durations.

Stage 5. Go to the Evaluation screen and read the story aloud. Write down your speaking rate and percent short syllables. Read the story again and try to get a lower percent short syllables, at the same or faster speaking rate.

Stage 6. Restart MPiStutter to clear the Cumulative screen. Use MPiStutter in a conversation. This could be face-to-face or on the telephone. Then go to the Cumulative screen and write down your talk time and percent short syllables. Have another conversation and try to get the talk time longer and the percent short syllables lower.

If you can't do Stage 6: because you don't have anyone to talk to, watch an infomercial, call the toll-free number, and ask questions about the product in the infomercial.

Stage 7. Use MPiStutter all day, until you have at least two or three hours of talk time. At the end of every day write down your talk time and percent short syllables. The next day try to get your talk time longer and your percent short syllables lower.

If you can't do Stage 7: because you don't talk 2-3 hours per day, if you have a job, ask your supervisor to let you talk to customers. If you're a student, talk more in class. If you have free time, do volunteer work that requires talking to people. If you have social phobia, see our webpage about speech-related fears and anxieties or seek treatment for social phobia. If you don't want to talk 2-3 hours per day, MPiStutter may not be the best stuttering treatment for you. If you don't like to talk and you just want a device to use when you need it, without thinking about it, get the SmallTalk.

Stretched Syllable vs. Relaxed Vocal Folds Targets

Note that MPiStutter can be used for the stretched syllable target (blue and purple phonation intervals) and MPiStutter can be used for the relaxed vocal folds target (green phonation intervals). You could use MPiStutter to support prolonged speech stuttering therapy (a.k.a. fluency shaping or smooth speech) and always use purple phonation intervals. Prolonged speech stuttering therapy with its stretched syllable target is the most widely practiced and most proven effective stuttering therapy. Vocal fold relaxation, i.e., the "sexy voice," is not target of prolonged speech stuttering therapy. Few SLPs can train vocal fold relaxation. On the one hand, the vocal fold relaxation target is what makes MPiStutter different from prolonged speech stuttering therapy and hopefully makes MPiStutter more effective for you. On the other hand, if you don't know how to do the vocal fold relaxation target and you can't find a SLP who can train you to do this target, then MPiStutter might not help you.

DAF Instructions

The DAF switches on when you speak too rapidly or stutter. When you hear the DAF, pause, relax your breathing and vocal folds and slow down, i.e., use the stretched syllable target. The DAF should switch off. When you can speak fluently without the DAF switching on you are ready to discontinue using MPiStutter.

As noted in Stage 1, use these targets with DAF:

  • Stretch vowels, not consonants. This is called continuous phonation.
  • Hold each syllable equally. Many people mistakenly hold each word equally. E.g., at one half-second per syllable the phrase, "I am American" should take three seconds, not 1.5 seconds. I.e., this phrase sounds like "I am A-mer-i-can."

DAF is most effective with a Sennheiser PC131 headset. The headset's binaural (two ears) sound is 25% more effective than monaural (one ear) sound. The headset's microphone picks up your articulated speech, including sounds produced by your lips, jaw, and tongue. The throat microphone picks up your phonation without articulation. With the medical accelerometer DAF sounds even less articulated.

Quitting MPiStutter

To quit MPiStutter, click your iPhone's "Home" button to go to the home screen, then double-click the "Home" button to display the running apps. Hold your finger on any app until the red - dots appear in the upper-left corners of the running apps. Tap the red dot - on MPiStutter to shut it down.


Real-Time. You see the last four seconds your speech in real time in the main window. Above the main window you see approximately the last ten minutes of your speech. In the upper screen try to make the green intervals tall and the red and orange intervals short. The number in the upper right corner of the Real-Time screen indicates the memory buffer. It should be zero or one or two digits. If it goes into the hundreds there will be a lag between when you talk and when you see your speech on the screen. With a 4th-generation or later iPhone or iPod touch buffering should not be a problem. Older devices may not be able to keep up with your speech.

Cumulative. This screen shows your phonation intervals since iStutter started. If you start iStutter in the morning and switch it off at night, the Cumulative screen shows how your speech for that day. The white clock shows your total speaking time for the day. The red clock shows your percent red or too-short intervals. Try to speak at least two or three hours each day, while trying to get the red number smaller every day. If you don't speak two or three hours per day then ask your supervisor for work that requires more talking, or volunteer for an organization that requires talking, or join a public speaking group such as Toastmasters, or just go out and talk to people.

Evaluation. This screen displays a story that has all the sounds of the English language. Click the "Start" button and start reading the story aloud. Scroll down and read to the end, then click "Stop." A normal speaking rate is 4 or 5 syllables per second. Try to get the % short intervals as low as you can.

Help. The help screen has these instructions.


Gain. Different microphones are more or less sensitive. Also, you may talk louder or quieter. The Iasus NT3 throat microphone should be set at 25. The throat accelerometer may need to be set to 0. A Bluetooth earset may need to be set to 100. Adjust the gain so that the black line indicating your vocal volume on the main screen goes to the top of the screen when you speak loudly but doesn't "clip" or flatten at the top of the screen, and when you stop talking the black line drops to the bottom of the screen and the screen goes white.

Delayed Auditory Feedback (DAF). This has three settings. The default mode is "Voice Activated" mode. Your voice switches on the DAF, and it switches off when you stop talking. The other settings are "Off" and "Always On."

Minimum DAF Hold Time. This sets how long the DAF stays on for, after you speak too fast and the DAF switches on. The default is 2 seconds.

Delay length. 75 milliseconds (ms) is for a "slow-normal" speaking rate, that is, a little slower then normal speech but you don't sound abnormally slow. 50 ms is for a normal or fast speaking rate. 100 ms and longer delays are only for abnormally slow speaking rates that are used in speech therapy. The 4th and 5th generation iOS devices have an additional 13 ms delay. If you want 75 ms delay then adjust this setting to 62 ms.

Analysis Time Period. The default is 2 seconds or half the screen, i.e., if too-short intervals appear in half of the main screen then the DAF switches on. To make this setting harder, increase this to 4 seconds or more. To make this setting easier, decrease this setting to 1 second.

Minimum Phonation Interval Duration. This sets what phonation intervals are too short. For most stutterers this is either 100 ms or 125 ms. Start at 100 ms. If you're speaking fluently and DAF switches on only occasionally, and then switches itself off a few seconds later, then the Minimum Phonation Interval Duration is set correctly. But if you're stuttering and the DAF doesn't switch on, then adjust this setting harder, to 125ms or 150 ms. If you're speaking fluently and the DAF is switching on too often, adjust this control easier, to 75 ms.

Required Interval Count. This is how many too-short intervals switch on the DAF. The default is 2 (in 2 seconds). To make this setting harder, change it to 1. To make this setting easier, change it to 3, 4, or 5.

Cut-Off Timing. If you use the Casa Futura Technologies accelerometer, set this at 30 ms. With the Iasus NT3 throat microphone, set this at 50 ms. The Iasus NT3 throat microphone picks up some false positives from breathing or movement in the 30-49ms range.


To a stutterer who hasn't had speech therapy and can't control his or her breathing, vocal folds, and speaking rate, the worst thing a listener can say is "Stop stuttering!" But to a stutterer who has had stuttering therapy and can stop, relax, and speak fluently then the best thing a listener can do is to alert the stutterer when he starts to talk too rapidly and is about to start stuttering. That is what MPiStutter does. Use it to keep your speech on target and fluent. It will alert you before you stutter, while you are still in control of your speech. If you wait until you are stuttering, you've lost control of your speech and it will be harder to regain control and speak fluently.

Show listeners your iPhone and say that you're using a speech therapy app to work on your stuttering. Listeners will ask you to explain how the app works. Then they will give you positive support for working on your speech. Hiding your stuttering will make your stuttering worse.

Join a shuttering support group, such as the National Shuttering Association.

If you are a Speech Pathologist who needs this app to evaluate clients who stutter, please contact us. We will try to obtain a free download code for you.

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