I am working on an app to provide Auditory Feedback to users to help speech fluency, comprehension, and pronunciation. Essentially trying to create a digital version of this product: Toobaloo (I have no affiliation with that product).

About Auditory Feedback they state:

What Is Auditory Feedback?

Auditory Feedback is the task of hearing the sound of one's own voice while speaking, which enables adjustments in pronunciation, clarity and the rhythm of speech. Auditory Feedback is used in speech, language, auditory processing and reading therapy programs.

However, by the nature of digital mediums and the apps implementation it is unlikely I will get the feedback down to real-time, according to Wikipedia a delay of even 175ms can result in mental stress as seen by Delayed Auditory Feedback :

Delayed Auditory Feedback (DAF)

is a device that enables a user of the device to speak into a microphone and then hear his or her voice in headphones a fraction of a second later. Some DAF devices are hardware; DAF computer software is also available. DAF usage (with a 175 millisecond delay) has been shown to induce mental stress.

Delayed Auditory Feedback - Wikipedia

However, I noticed both of these statements dicatate that the feedback is provided in the users own voice.

I was wondering if there was any research available in changing the voice of the feedback to help reduce stress and confusion from feedback delay?

EDIT: Conversely, if changing the voice decreased the stress and confusion from Delayed Auditory Feedback would it also decrease the benefits of Auditory Feedback on speech therapy?

  • That'd be interesting research. I would hypothesize that the stress comes from the unexpected delay of hearing your own voice, since approximately 99.999% of your life, you hear your voice in real-time (e.g. you hear yourself speaking). I could imagine why a delay would cause mental confusion, since we've basically "programmed" our brains to expect our own voice to be in real-time.
    – phyrfox
    Commented Aug 24, 2015 at 18:38
  • I agree this would be something I would love to research myself but at the moment don't have the means to due real user tests for something like this. (would have to bring in real users and measure their stress levels, etc.) I wonder if hearing a different voice overrides that "programming" to expect our own voice, also perhaps the more different the easier it is to perceive?
    – DasBeasto
    Commented Aug 24, 2015 at 19:02
  • The stress is not related to the voice being yours. The stress is created because you are hearing the same thing you are saying with a slight delay. You start speaking more slowly as if waiting for your ears to catch up with your mouth. Your brain thinks it's hearing your voice, not a recording of your voice from 250 ms ago. Each person is different, but for most people you can find a sweet spot for the delay value that will stop them from being able to say complete sentences. A different pre-recorded voice should cause no problems or stress at all. Something like singing along to a song.
    – irreal
    Commented Aug 25, 2015 at 12:15
  • youtube.com/watch?v=J6m4NndjFPo speech jammer video, radio 1 did a load of things with speech jamming. As you say, it seems that your own voice might have an impact, though as your own voice never sounds the same as you perceive it in recordings anyway I'd suggest that it's the rhythm etc that is more jarring and not the tone etc. If you could make a speech feedback that was also different in how it is delivered rhythmically, tonally, volume-wise, pitch etc that might work but I've not seen anything about it
    – Chris
    Commented Sep 2, 2015 at 11:38
  • 1
    Additionally...when practicing singing or testing a new piece of gear, I used to set up a DAW or plug headphones into a piece of in/out hardware directly, and sing into a microphone with the headphones loud enough that my digital voice was louder than the voice I could hear through my bones. (It wasn't deafeningly loud, either.) The result was similar to what you're describing: I could focus on my inflections, pronunciation, and the sound of the effects, as if I was hearing a recording of myself.
    – Nate Green
    Commented Jan 4, 2016 at 21:57

1 Answer 1


Here are related findings, they are not nailing the question but can be interesting for followers...

Using delayed auditory feedback (delay 0.175 s) a standardized form of mental stress was investigated in 8 healthy male volunteers. After a resting period and a period of undelayed reading, the volunteers were exposed for 5 min to the DAF stress. During the DAF period heart rate increased by 10% and systolic and diastolic blood pressure increased by 9% and 18%, respectively. As a measure of acute sympathetic activation, plasma concentrations of norepinephrine and epinephrine rose by 68% and 49%, respectively. The activity of dopamine-fl-hydroxylase in plasma was increased by 25%. From these results it can be concluded that the DAF procedure provides a suitable method for inducing a standardized mental stress in normal subjects, which can be measured as changes in biochemical and cardiovascular variables. [1]

DAF used as treatment for prolongation or slowing of the rate of speaking also for stuttering cases. The delay rate works differently at children and adults. Delay and volume(dB) changed to check the therapeutic applications.In addition to this, if you are bilingual, the results are showing differences with normal group. [2]

I didn't find any new research that is going-on about reducing the stress. Thank you for asking a good question.

[1] Badian, M., et al. "Standardized mental stress in healthy volunteers induced by delayed auditory feedback (DAF)." European journal of clinical pharmacology 16.3 (1979): 171-176.

[2] McCormick, B. (1975). Therapeutic and diagnostic applications of delayed auditory feedback. British Journal of Disorders of Communication, 10(2), 98-110.

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