Measure THD of a Song.

[rachitdave]

Hello,

I am using mini DSP MIC. I want to measure THD of a song clip that is played in Android Phone and recorded using mini DSP MIC using Audacity.

What actions are done till now:
1. Recorded sweep tone from 20 Hz to 20000 Hz using miniDSP Mic and capturing the recording in Audacity. Imported the wav file in RTA. THD results are not as expected.
2. Recoded fixed tone of 1000 Hz using miniDSP Mic and captured recording in Audacity. Imported the wav file in RTA, THD results are as expected.

Please do guide me how I can measure THD of a song clip using REW.

Thanks in advance.

 

[John Mulcahy]

The help covers measuring with file playback, which uses an REW measurement sweep.

 

[rachitdave]

Hello John,

I want to measure THD of a song and not sweep.

 

[John Mulcahy]

REW does not have a way to do that.

 

[JLM1948]

No one can measure the "THD of a song". THD depends on frequency and level; it can only be measured with fixed tones (at least fixed enough to allow measurement to settle).
One thing is not clear: do you want to evaluate the THD inherent to the song, or the THD resulting from passing the song through your equipment.
The latter could be understandable, although not possible. The former just makes no sense.

 

[charleski]

the THD inherent to the song

While the production of the song will almost inevitably have involved effects that distort the original audio (distortion in the mic electronics, EQ, compressors, explicit distortion effects, etc.) it’s impossible to measure that without having a reference signal. If you just want to compare a song as processed by your playback/recording chain to the signal that’s input to the system then you could try DeltaWave, though interpreting the results will be more complex than looking for a simple THD number.

As JLM1948 says, the important thing (as with most of science) is to be very clear about exactly what question you’re asking.

 

[rachitdave]

No one can measure the "THD of a song". THD depends on frequency and level; it can only be measured with fixed tones (at least fixed enough to allow measurement to settle).
One thing is not clear: do you want to evaluate the THD inherent to the song, or the THD resulting from passing the song through your equipment.
The latter could be understandable, although not possible. The former just makes no sense.

Hello JLM1948, I wanted to measure THS resulting from passing the song from my equipment that is an Android Phone. It makes sense that I will not be able to measure THD of song as there will be multiple frequency superimposed and SW will evaluate based on the fundamental.

 

[rachitdave]

While the production of the song will almost inevitably have involved effects that distort the original audio (distortion in the mic electronics, EQ, compressors, explicit distortion effects, etc.) it’s impossible to measure that without having a reference signal. If you just want to compare a song as processed by your playback/recording chain to the signal that’s input to the system then you could try DeltaWave, though interpreting the results will be more complex than looking for a simple THD number.

As JLM1948 says, the important thing (as with most of science) is to be very clear about exactly what question you’re asking.

Understood. Thanks for the feedback.