Audio numbers (ex. 16/48)

[ra1024]

I've seen audio formats listed like the following and was wondering what these numbers meant and their significance.

LPCM 16/48
DD THD 24/48

I believe these indicate the number of bits and the sampling rate but didn't know what the range was and how they related to the audio quality.

Can anyone give a brief explanation on these? I want to be able to look at titles and know what I'm getting.

[WriteSimply]

Wikipedia to help you out.


fuad

[ra1024]

Thanks for the link but I may not have asked my question well. That article explains sampling which I have a limited background in from my EE days at GT.

I'd like to know what the first number represents and what the second number represents when you see these audio formats listed in the home audio arena. The article doesn't mention the range that we'll find on BR or HD DVD which is also what I'd like to understand. For example, if a soundtrack is listed as 24 bit, is that the highest level or the lowest?

[Ascended_Saiyan]

24 Bit is the highest quality sound movies are currently done it, as far as I know. Some movies are mixed at 16 bits, so those can't go higher than that. I don't know much beyond that. I hope that what you are looking for.

[MatrixS2000]

16/48 = 16 bit, 48Khz
24/48 = 24 bit, 48kHz

16 and 24 bit = # of sampling bits, higher is better. 24 bit sample has more resolution than a 16 bit sample.

48Khz = Sample frequency so 48Khz = 48,000 samples/sec

How is that for short?

[ra1024]

Thanks for the info. That's what I was looking for

Does anyone know what the range is for the sampling frequency? I thought I had seen 96 listed at one point.

[Deciazulado]

16 bit you use as the quantization noise vs signal. For example 16 bit without dither gives a theoretical 16 x 6.02 dB = 96.32 dBs of s/n

24 x 6.02 = 144.48 dBs

If you add mathemathical dither the figure is reduced 1.76 dBs but there's much better improvement in the sound of the signals near the noise floor level so we can "perceive" sounds "below" it.

Normal range for the human ear is usually stated as going from 0 to 120 dBs.

48 kHz refers to the sampling frequency. 48kHz is used to record up to a 24kHz limit

Normal frequency range for the human ear is usually stated as going 20 Hz to 20kHz, altho you may distinguish time differences smaller than that for stereo discrimination.

depending on the format, the highest consumer sound has been 192 kHz samping for PCM DVD-Audio and 2.82 MHz (2,822 kHz) for DSD SACD

[ra1024]

If the human ear can't hear above 20khz, why do they sample above 48khz? 192khz just seems like insane overkill unless you have dogs in the audience.

[Filterlab]

Originally Posted by ra1024

If the human ear can't hear above 20khz, why do they sample above 48khz? 192khz just seems like insane overkill unless you have dogs in the audience.

There's been a massive amount of research done in this area, too much to type in full. The outline of it is that the human hearing may only be attributed to interpret frequencies up to around 20Khz, however the natural dynamic range of musical instruments and standing waves/environmental affects go way beyond that figure. Therefore capturing those frequencies adds to the overall effect of music.

Also, the more resample calculations, the less chance of something important being missed. There's also the halving effect - limitation of resampling cuts the response range of high frequencies in half; i.e. 44.1Khz (CD) tops out at 22.05Khz audible frequency etc etc etc.

Have a look at Townshend's page on supertweeters, there's loads of info on there. http://www.townshendaudio.net/index....d=27&Itemid=81

[ra1024]

Originally Posted by Filterlab

There's been a massive amount of research done in this area, too much to type in full. The outline of it is that the human hearing may only be attributed to interpret frequencies up to around 20Khz, however the natural dynamic range of musical instruments and standing waves/environmental affects go way beyond that figure. Therefore capturing those frequencies adds to the overall effect of music.

It sounds like what you're saying is that with the higher frequencies, the sound wave is actually different which I agree and understand. The thing I've never been able to understand is how someone could truly hear a difference. If the human ear can't hear those frequencies, it would seem that it's acting as a low pass filter and the sound wave delivered to your brain is thus delivered with those frequencies removed. This would then seem to be the same wave you would hear without those recorded in the first place.

I'm not arguing that they're wrong, I've just don't see how it can be the case. I looked at that link and it seemed to say that people could hear a difference but didn't really explain why. I guess the answer to my question just boils down to people can hear a difference. Someday when I have time I may search out for some research explaining how this can be but for the moment, I'll just settle for knowing it does happen.

Thanks for the info

[MatrixS2000]

Think of it this way - you also can hear below 20Hz, but I bet you can feel it and when you watch a movie with that deep rumble that you can feel but not hear - it adds to your experience.

The think with the higher freq is a very old argument and was really raging when people first went from records to CDs. Many complained that the records sounder warmer than the CDs since the record was a analogue playback and could reproduce all the harmonics.

[Deciazulado]

Originally Posted by Deciazulado

Normal frequency range for the human ear is usually stated as going 20 Hz to 20kHz, altho you may distinguish time differences smaller than that for stereo discrimination

.

[ra1024]

"altho you may distinguish time differences smaller than that for stereo discrimination"

I have no idea what you meant by that which is why I asked the follow up.

[Deciazulado]

Originally Posted by ra1024

"altho you may distinguish time differences smaller than that for stereo discrimination"

I have no idea what you meant by that which is why I asked the follow up.

Ok .
Some people have proposed that since we can hear timing differences between signals reaching the two ears smaller than what a 20kHz frequency response sampling limit might suggest, the sound would have better "depth" and "focus" when sampled at higher frequecies. The theory is that you have two "mics" that reach 20k. But the brain can analize timing differences between those 2 mics finer than that.