- It's got to be a sound you are familiar with. You know the sound of you front door and you know the sound of a soda or beer can being cracked open. Sounds like these are powerful in that they instinctively trigger thoughts and emotions prior to you actively conceptualizing their source. The sound you use for echolocating should be similar to this so that you are familiar enough with it to recognize the very subtle variations that are necessary for echolocation.
- It's got to be consistent. Whatever it is try not to change it up to often unless you experimenting. One sound may return different reverberant characteristics than another in the same environment.
- You've got to be able to hear it. It doesn't make a lot of sense to make a sound that will be difficult to hear, which implies that the sound wave must have enough energy to return to your ear, and still be recognizable. Higher frequencies have a higher energy than lower frequencies and therefore will return better. They will also give you better resolution since the wavlength is shorter.
Here are a few of the different tones I've been experimenting with:
- Car engine. This is used when driving with the passenger's side window open and echolocating passing objects. Read echolocating while driving in the car, for more, but you've got a great tone for a lot of reasons:
- There are many different frequencies present.
- It is consistent.
- It is loud. I have been able to echolocate and determine the shape and material of objects up to about 50 feet away from the car.
- It is not directly heard inside the car. Meaning most of the sound is outside the car and can be reflected inward making the reflected sound the dominant one as opposed to the source.
- Footsteps. These are okay to use since they are generally distinct and high frequency, but I find that they are very inconsistent depending on the terrain and what kind of shoes you are wearing.
- Scuffing of pant legs. Fairly consistent, but usually just not loud enough.
- "Cluk" - The sound of the tongue smacking the bottom of the mouth as if to make a "clop" or "pop" sound. As far as I can tell this is what most practicing blind people do including Ben Underwood. It gives a nice quick defined tone that is fairly high pitched. And since the mouth is closer to the ears than say, the feet, the reverb characteristics, I would think, are more accurate.
- "Kik" - This is a sound made on the sides of the tongue as if you were guiding a horse. It is made by sealing the tongue against the roof of the mouth and creating a negative pressure inside your mouth and then releasing your tongue's seal. It will result in a "kik". I've taken a liking to this one for a few reasons:
- It's even higher pitched than the "cluk".
- It's easier for me to make, therefore I can make it louder.
- It emanates from the sides of the mouth rather than the front thus reflecting more of the tone directly back into the ears.
So I'm going to keep using the "Kik" method and we'll see how that goes. Another thing I wanted to try was snapping with my fingers somewhere under my chin. I will try this and report back if it is any good. The reason I say under the chin, is so that the sound source is close to my ears, but the direct signal is somewhat blocked by the underside of my face leaving me with a better perception of the sound as reflected back.