![]() Noise is well studied and regulated by OSHA and the CDC because it can be harmful in several kinds of ways. Digital noises that are not deliberately faded in, but just “turn on” can be impulse noises. Exploding gasses, mechanical impacts, and explosions are impulse noises. ![]() But humans create all sorts of impulse noises. Impulse noises are likely more common in human society than in nature. An impulse noise goes from zero to a high volume in such a short time that it is perceived as instantaneous. The following noises are all what acousticians call impulse noises. I want to show you what the sounds of the clicker and other mechanical markers look like. OK, now we get to the good stuff, the point of this article. Here is a chainsaw being used to cut down a tree. (This is the image of me saying, “Here is what talking looks like.”) This particular sound starts abruptly, but stringed instruments can also fade in. String instrument sounds played with a bow don’t necessarily decay. Then the amplitude decreases (decays) quickly over time on each one. Even the very soft one has a definite beginning. Note how the sound starts off very suddenly (the piano is actually in the percussion family of instruments). Here is the C above middle C (C5) on a piano, played at loud, medium, and soft levels. But most of the sounds are too complex to show oscillations at all. For the piano and violin, the frequency is too high for us to see individual oscillations at the given scale on the page. Most of the sounds I’m going to show you are of this variety. I’m not going to get into pitch, because if there are many different frequencies playing at the same time, we don’t hear pitch at all. Bad audio engineering behavior on my part!) Several of the click sounds “saturated” the scale, meaning that their volume exceeded the bounds of the scale at the distance from the microphone I used. (If you are curious, the y-axis is on a linear scale to help the user know their recording level. Giving readings in decibels would be misleading. But because these sounds were recorded in different situations, I didn’t control for the distance between the sound source and the mic. I am not including details for the y-axis. The x-axis (horizontal) is time in seconds. Instead of talking a lot about it, I’m going to show you a lot of examples. So I’m going to give you some examples of what various sounds “look like.” We’ll examine their amplitudes (volumes), rhythms, and onset times graphically over time. Waveform diagrams allow us to translate the aspects of a sound wave into a visual presentation. As an auditory-oriented person, I run up against this problem a lot. We don’t have enough words in English to describe sounds.
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