“If you tell me that story one more time I’ll use my Speech Jammer on you…”
Invented by Japanese Professors Kurihara and Tsukada, the speech jammer can forcibly (but perfectly harmlessly!) inhibit someone’s speech. I’m sure you can already imagine the endless applications of such a device... No more incessant nagging from you know who... No more interruptions from a strangers’ public phone chatter... No more boring monologues from an oblivious colleague... Finally, you can secure your peace at the push of a button!
Simply point the speech jammer at a noisy individual, and silence them… with their own voice!
Want to know more? Read on…
“But my voice doesn’t sound that bad…”
A speech jammer records and plays your voice back to you at a slight delay. But your inability to talk coherently whilst hearing yourself isn’t a matter of self-consciousness (like not liking the sound of your own voice on voicemail). It’s a bizarre, yet explainable, scientific phenomenon called delayed auditory feedback (DAF).
Usually, when we are speaking, the sound of our own voice is fed back to our inner ear through vibrations in the air and our middle ear bones. There is therefore a slight delay before we perceive it. So slight, in fact (about 0.001 seconds), that we can’t even detect the pause.
However, speech jammers play own speech back a much longer delay than this (usually about 0.2 seconds), meaning there is an audible echo.
As you’ll know if you’ve ever experienced the struggle of trying to talk on an echoey phone, hearing yourself like that is very off-putting and quite frankly just strange.
But as it turns out, DAF does more than just disconcert the speaker; it renders it near-impossible for them to speak normally. Numerous studies conducted on DAF have shown both its direct effects on speech. For example, someone may:
- Repeat sounds
- Mispronounce sounds
- Omit sounds
- Add sound
- Substitute sounds
It also results in indirect effects as the speaker tries to regulate or normalise their speech: they might speak more slowly and/or enunciate their words more clearly. So if we were to use a speech jammer on a talkative neighbour and they were determined to continue their one-way conversation, what you’d hear is artificial stuttering.
In order words, they’d sound a lot like this:
Why does Delayed Auditory Feedback cause stuttering?
In day-to-day conversations, our brain is constantly monitoring our own speech to ensure we’re saying things correctly and making adjustments based on the sound fed back. This system is called the auditory feedback loop – we say something, we hear it, and we process it (and correct it if necessary). The auditory feedback loop allows us automatic control over our flow of speech and keeps us expressing what we’re trying to convey.
When a speech jammer is used, our brain can’t separate out our own voice (the immediate feedback) from the recording (the delayed feedback). Instead, it interprets the overall feedback as our speaking incorrectly since the expectation for what your speech should sound like isn’t met. This disrupts the auditory feedback loop as our brain pauses to make alterations, resulting in disruptions to our speech too. The distortions in our words such as stuttering and slurring are caused by the changes our brain makes in an attempt to amend what it perceives as incorrect speech.
All this talk of talk…
You don’t have to take our word for it, try Speech Jamming for yourself!
A few things to try:
- Play around with the delay time – how does this influence your speech?
- Compare different types of speech – how successfully can you speak spontaneously versus reading aloud (if there’s nothing to hand you could read this article to yourself)?
- Challenge yourself to overcome it – theoretically, with enough practice, we should be able to teach ourselves to talk normally even with DAF!
You may find that you can speak easily at the beginning of a sentence but start to stutter towards the end. This is because to begin with, your brain is only basing its response on the immediate auditory feedback and isn’t yet confused by the DAF.
What if someone already stutters?
DAF, which induces stuttering in a non-stutterer actually reduces it in stutterers! In fact, it can help improve the fluency of stutterers so effectively that it has been developed as a treatment!
While there is no one known cause for stuttering, it is well established that when someone says the same words at the same time the stutterer (known as choral speech), fluency improves. The SpeechEasy is a device that sits in the ear a bit like a hearing aid and plays the wearer’s own voice back at a slight delay (DAF) and at a slightly different pitch (frequency altered feedback). The brain then interprets this as a different person speaking alongside the wearer, simulating choral speech and thus reducing stuttering.
Can Speech Jammers be used on animals?
No doubt you’re beginning to see the potential for speech jammers, and can possibly imagine several useful applications. But what about the next door neighbour’s dog that’s always barking? Is a speech jammer the good night’s sleep we’ve been looking for?
Testing speech jammers out on animals is easier said than done. Not many animals produce sound that’s as constant as human conversation, so we’re never going to get an ideal test subject. But songbirds are pretty close – they’re vocal learners, meaning they’re often used as animal models in studies of speech. In fact, songbirds rely on auditory feedback similarly to humans – they need it for the development and maintenance of their songs.
Researchers found that zebra finch songbirds changed the timing of their syllables when exposed to continuous DAF. It just took a little longer compared to humans for this effect to be seen – a matter of days rather than seconds. When researchers stopped the DAF, the zebra finches took over a month to return to their original song patterns, whereas you and I can speak normally as soon as the DAF ceases.
So while speech jammers probably won’t be helping you quiet your pets anytime soon, it’s still an interesting avenue for exploration.
What does Delayed Auditory Feedback teach us?
DAF highlights the importance of our auditory feedback loop. We depend on auditory feedback for vocal control and learning, meaning it is essential for normal speech development and maintenance, and ultimately for all spoken communication.
So what happens if we’re not receiving this feedback as well as we should?
If we can’t hear our own voice clearly, the auditory feedback loop is disrupted. This is one of the reasons why we raise our voices in background noise: it's as much about being able to hear ourselves talk, as it is so others can hear us.
Similarly, if we have a reduction in our own hearing, we’re far more likely to experience difficulties with our own enunciation or fluency. So what do we do as a result? We either raise our voice to hear ourselves better (= other people telling us we’re speaking too loudly!), or we find it easier not to talk as much (= less social participation). Neither are ideal.
So here’s what Delayed Auditory Feedback teaches us. Not only does our hearing connect us to others; it appears to connect us to ourselves too.