Hello ,
I need to measure dynamic range of my codec TLV320AIC3104 using Audacity S/W . Will you please tell me how i can achieve this .
Best regards ,
Falguni
The TLV320AIC3104 has a dynamic range of 93dB (specifications). This cannot be measured in Audacity because the surrounding circuitry and other factors increase the noise floor before any signal is available to Audacity.
There are several definitions of “dynamic range”. A common and easy to measure definition is the difference between the maximum signal level and the noise floor. Assuming that you are able to record at full track height (0 dB), then the dynamic range of the system is simply the inverse of the noise floor. So if the noise floor is -60dB, then the dynamic range can be said to be 60dB.
If you can’t hear noise (hum, hiss, or whine in the background) it’s good enough. 
For the ADC you can simply record silence (with nothing connected or the inputs shorted to ground) and then check the noise level.
Measure RMS is built-in. Or there are other Analyzer plug-ins.
For more extensive testing can try RMAA. But generally it’s “testing itself”, looping through the ADC and DAC so you’ll get a combination of the worst of both.
90dB would be unusual FOR A “soundcard” in the real world, especially for the microphone inputs. Microphone preamps generate noise (all analog electronics generate some noise) and the noise is amplified along with the signal.
Computers are electrically noisy internally and USB power tends to be noisy. That’s no problem for digital but sometimes the noise gets into the analog electronics, depending on how well everything is filtered and shielded.
There are USB audio interfaces that can beat 90dB on the mic inputs but they usually have a separate preamp circuit. And your odds are better when it has its own power supply, since the noise in USB power is unpredictable.
Noise specs are often A-weighted to account for the fact that our ears are most-sensitive to mid frequencies. That gives a “better number”.
USB power noise is unpredictable, but it is measurable. A device like a FNB48P or FNB58P (Google them), or a similar USB power tester with a simulated digital oscilloscope, between the power supply and the device will show you.
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