Blog about voice enhancements

Inspire Communication at MWC 2012

Too soon to blame your phone if you hear yourself!

Have you ever blamed your cell phone because you heard yourself while talking to your friend over the phone? Really irritating, isn’t it? If that is the case, there is something you need to know before you throw away your phone. Let’s have a look at what happens inside your phone and in your friends’ phone.

First of all, congratulations. Your sensory organs are working normally because your ear is hearing yourself. You are hearing an echo of your own voice and although echoes can be very annoying, your ears are working perfectly fine. Let’s see what happens when we are talking. Our vocal cords vibrate to produce sound waves. These sound waves will travel over the air to other people’s ear drums as well as over our bodies to our own ear drums. Unconsciously, like it or not, we have been hearing ourselves since we learned how to speak, which has been that way for us over several decades (at least, for most of us). But why is it so annoying to hear yourself back when talking on the phone? The truth is that we have just heard ourselves three times:

  • 1st time: From your throat to your ear drums over the bones in your head.
  • 2nd time: From your throat to your ear drums over the air. In this case, the sound wave propagates slower over the air than over solid or liquid carriers.
  • 3rd time: From the other side of the call.

The first arrival is what happens with all of us, no matter how we talk (unless you speak a sign language). Thus, this never irritates us.

The time difference between the 1st and the 2nd arrival is very small. Small enough to consider them as one single arrival at ‘human’ interpretation. The 2nd arrival is still very different though. It’s an important component when we hear ourselves. Imagine a small experiment that you might have conducted as a kid: Cover your ears with your hands when talking. Your voice sounds completely different from when your ears are uncovered. Now this is exactly what happens when you are on the phone. The phone covers your ear from the sounds in your surroundings. Your voice is travelling through the air but it’s blocked the phone and this adds up the ‘weird’ experience. There is a solution to overcome this weird experience – called ‘side tone’ in telecommunications lingo. How it works? Very simple. The speaker plays what the microphone captures at a certain volume level.

The biggest difference we notice – and most annoying – is the 3rd arrival. When you are on the phone with your friend, the speaker of your friend’s phone plays what you are saying. While the speaker is playing your voice, the microphone is supposed to only capture your friend’s voice. Unfortunately, the microphone captures not only his voice but also the noise around him and what the speaker is playing. Everything that the microphone captures will travel to your phone and that’s why you will hear more than just your friend’s voice – you also hear yourself played back on the speaker of his phone.

To be continued…

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