I am currently having trouble understanding the significance of negative amplitudes in a traditional Sound Wave, such as in the Short values of Android's Audio Record.
1. Is the amplitude still the distance between zero and the value of the node (absolute value), or the distance from the previous node to the current?
Basically, I am looking into Ludvigsen's Sound Classification Technique (1993), but the demonstrations I have looked in show only positive values.
2. Some Sound Waves have negative values after a previous negative value (or vice versa) rather than bouncing below or above zero after each value. Such as center of image at: http://puu.sh/a0dhg/62b2a5c6da.png (I cannot post images directly yet due to missing reputation).
Therefore my remaining question is: When does a Sound Wave "decide" to go above or below zero? Since I was of the idea the below-zero is sort of a retractions of a previous above-zero value (compression being pushed and bounces back), but moving in the same direction in relevance to zero seems somewhat illogical.
That's pretty much it, thanks in advance. Your help will be most appreciated.
The amplitude of a wave is a measure for its strength (loudness in case of sound). It basically tells you how far the wave swings away from the neutral position. Several definitions do exist, see for example Wikipedia.
The frequency of the wave is a measure of how often in a second it swings a full period (zero - max value - zero - min value - zero).
Any sound can be thought of a composition of several pure sine (and cosine) waves of different frequencies and amplitudes.
