What are the frequency limits of pcm wav?

[BirdDaddie]

I have tried searches like google but the results all have to do with editing and do not give specifics

[SingSing]

For sampling and playback at 44KHz, it will be 22KHz.

[JohnnyMalaria]

According to MS documentation:

nSamplesPerSec

Sample rate, in samples per second (hertz). If wFormatTag is WAVE_FORMAT_PCM, then common values for nSamplesPerSec are 8.0 kHz, 11.025 kHz, 22.05 kHz, and 44.1 kHz.

nSamplesPerSec is a 'DWORD' which means it can range from 0 to 4,294,967,295.

So, *in theory*, the existing PCM WAV format can accommodate any sampling frequency up to 4.3GHz!!!! (As long as it is a whole number of Hz).

In practice, you can choose any value you like - the limitation will be whether any associated hardware supports it or not.

Whatever the sampling frequency, the maximum reproducible frequency will be exactly half that.

[greymalkin]

so just out of curiosity, what is your application? Or is it just a curiosity?

[liquid217]

Whatever the sampling frequency, the maximum reproducible frequency will be exactly half that.

Hence, the Nyquist theorem
http://en.wikipedia.org/wiki/Nyquist-Shannon_sampling_theorem

http://en.wikipedia.org/wiki/Nyquist_frequency

[Cornucopia]

Trying to be practical, you'll need to stay within usual guidelines for sample rates, etc so that more mainstream applications can understand the files and be able to work with them.

That gives you sample rates of:

8, 11.025, 12, 16, 22.050, 24, 32, 44.100, 48, 88.2, 96, 176.4, and 192kHz

which when using the Nyquist theorem will give you upper frequency availabilities of:

4, 5512.5, 6, 8, 11.025, 12, 16, 22.050, 24, 44.1, 48, 88.2, and 96kHz

(these may all be a little less because of non-perfect filtering)

The last 4 items won't be available in many programs, unless they're either very recent or were made to specifically accept higher samplerate material. Also, you may be able to convert/generate and save material in that high samplerate format, but unless you have a playback system that FULLY SUPPORTS high sample rates--ALL THROUGH THE CHAIN, you won't be able to enjoy it.
Meaning, that whatever is the weakest link in your playback system (player software/hardware, drivers, soundcard/soundchips, cabling, receiver/D-to-A converter, amplifier, and speakers) will determine the highest frequencies heard. Oh, yeah--EARS, too!

Scott

[BirdDaddie]

I am wanting to do research on animal's hearing

[jagabo]

Do you have speakers that will output sounds over 20 KHz?

[BirdDaddie]

some peizos I have from a project long ago,I know they do ultrasonic,I don't have the specs on them

[SingSing]

Peizos has strong odd harmonics, so the subject will react to 3x,5x,7x... of the test frequency. A Heil transformer is a better transducer.

[raquete]

@ JohnnyMalaria and Cornucopia
wonderful lessons,cool posts! 8)

@ jagabo

Do you have speakers that will output sounds over 20 KHz?

very cool question!
when i asked in another forum about where they do they "scientifics tests" using "what speakers with what frequence range" and i was trying to explain that for audio scientific tests they in the end was using the ears....boom,was a "blasfemia"

[raquete]

Peizos has strong odd harmonics, so the subject will react to 3x,5x,7x... of the test frequency. A Heil transformer is a better transducer.

hy SingSing
re reading this whole cool treat i saw that your observations are very interesting and takes me to this question:
how "they" read and measure the odd harmonics,distortions,etc in piezos?
what "aparatos" and parameters are used?
thanks!

[MOVIEGEEK]

I've seen piezo tweeters go to 55KHz and should work for animal testing,piezos also don't require a crossover.The only problem is the dB level will be too high and may cause hearing damage,make sure you use a dB meter and keep the volume under 90dB.
http://www.lsu.edu/deafness/HearingRange.html

[raquete]

thanks for the link about "hearing range" MOVIEGEEK,very good.
do you know another one showing how the frequences and levels are measure from piezos?...how can be measure and what tools are used? ! ?
thanks so much