Compressed Audio Question

[Ghoostknight]

Again, this is very easy to test yourself, a square wave sounds the same as a sine wave at say 12kHz because the difference is the square wave has (inaudible) harmonics.

just to clarify... if i play a 8khz squarewave, does it have harmonics at just 16khz or at 12khz too?

i was able to spot a small difference with 8k pretty clearly between square and sine wave ... the square wave had something "metallic" sounding to it
with 12k i was able to spot a kinda very small difference but could be potentially placebo

 

[VNandor]

just to clarify... if i play a 8khz squarewave, does it have harmonics at just 16khz or at 12khz too?

i was able to spot a small difference with 8k pretty clearly between square and sine wave ... the square wave had something "metallic" sounding to it
with 12k i was able to spot a kinda very small difference but could be potentially placebo

This test is surpisingly easy to mess up, especially if you don't really understand what you are doing. If you play a 8kHz square wave the first harmonic should be at 24kHz! Remember, a square wave contains all the odd harmonics with no other harmonics. If you managed to properly generate a square wave, you should not have any harmonics at either 12kHz or 16kHz.

You must have at least a basic understanding of the software that you are using to generate the square wave. Does it generate a square wave that's sampled at 44.1kHz for example:? If that is the case, the 8kHz "square wave" it outputs is supposed to be just an 8kHz sine wave. If it isn't working properly, it will alias the frequencies over 22kHz back to the audible range. Keep in mind, it is not possible to generate a frequency over 22kHz if you use a 44kHz sampling rate!

The metallic sound you are hearing is very likely coming from the massive aliasing of your generated "square wave". Try to use a program and check if that is indeed what is happening. If you generated a 12kHz square wave with a sampling rate of 44.1kHz with anti-aliasing properly applied, the analyzer shouldn't show any other frequencies beside 12kHz. Keep in my the program you use for checking that also uses sampling so that is also susceptible to aliasing.

If you used a sighted test it could be placebo. If you didn't use anti-aliasing while generated the square wave, you might hear the aliasing.

 

[71 dB]

A bass covers three octaves, doesn't it? That would be around 40 to 320Hz.

To me bass is 20-200 Hz which is 3.321928095 octaves. How this range is used depends of the music genre.

 

[71 dB]

In music the bass that carries most of the load is 80-160Hz. Everyone thinks it's the sub bass below 80, but sub bass is just a rumble. It doesn't have a lot of definition.

Try some drum 'n' bass for example tracks and you'll hear well-defined bass below 80 Hz. Even when it's "just a rumble", it is important body for the sound shaping the transients properly.

 

[71 dB]

A CD can actually extend below 20Hz.

There is no lower limit for frequencies that can be put on a CD other than the time limitation. Since CDs can be about 80 minutes long, the lower limit for frequency is 1/(60*80) Hz = 1/4800 Hz = 0.0002 Hz. CD players however use highpass filtering typically around 2-5 Hz I believe. CD covers the lower end of human hearing range with total ease. It is the speaker system that struggles!

 

[71 dB]

It should also be evident with folks that there are modern music genres that are all about the bass

Yes and I am into many of those.

(should I try to resist including the link for Meghan Trainor?).

You should! Meghan Trainor's music is some of the most annoying pop music out there.