[wyager]

So, when I asked about how sound worked in the 16 vs 24 bit thread I learned a lot of the stuff I thought I knew about sound was wrong. One of the things brought up was the actual sound waves versus what voltages you feed the speaker. For the last few hours, I have been working on some wave generation equations, and I thought I would compare measured electrical waves versus measured acoustical waves. I couldn't find this anywhere on the internet, so did it myself.
 
Procedure:
All waves are generated at 16 bit @ 44100khz, all at 500 hertz and roughly the same peak amplitude (according to my laptop). The electrical waves are measured by shorting the ground and input/output pins of a $2.80 USB DAC/ADC (Which, at this price, is VERY noisy, as you can see in the pics. However, it is good enough for our purposes.) I used this because A)I can't find a male-male 3.5mm cable and B)I don't want to damage my laptop, it barely works as-is. The acoustical waves are measured by holding my triple.fi 10's (connected to my macbook's audio out) up to my macbook's microphone (also very noisy due to the fan's whirring/low microphone quality, but good enough). The results are as follows:
Digital sine (ignore the dirtiness from the cheap DAC/ADC):

Acoustical sine:

Digital full square wave:

Acoustical full square wave:

Digital half square wave (either my equation is messed up or the DAC really hates positive-only voltages, I think the latter may be the problem):

Acoustical half square wave:
 

Digital sawtooth wave:

 
Acoustical sawtooth wave:

Digital triangle wave:

Acoustical triangle wave:

I hope this information is interesting to someone!
Cheers,
Will