If I import a WAV file that was set at a sample rate of 41000, I thought Audacity would “automatically” change the same rate to the Project Rate. I have made sure the Preferences: Quality Default Sample Rate is 48000.
I have a set of tracks in a Project where the sample rates vary from track to track: Either 41000 or 48000. If I try to overdub the existing tracks with a new recording, it has the wrong pitch and the wrong speed.
I can correct this by using the Tracks/Resample command on each 41000 track. Does Audacity not import audio AND change the sample rate?
If you import a 2nd file into the same project and it has a different sample rate, I believe it will be resampled to match the 1st one and the project.
(The bit-depth is converted to 32-bit floating-point.)
When you import a file into an empty project, Audacity automatically changes the “Project Rate” to match the imported file. This only happens when importing into an empty project. If the project is not empty, the imported file will create a track with the same sample rate as the imported file, but the Project Rate will not automatically change.
The “Project Rate” is the operational sample rate for the project. A project may contain multiple tracks with different sample rates, but the computer sound system requires that each audio application plays back using just one sample rate, so if necessary, Audacity will automatically resample tracks during playback so that the computer sound system receives the audio data at the “Project Rate”.
On exporting to an audio file, the audio file must have just one sample rate, so again Audacity will resample the audio data if necessary to the “Project Rate” to create an audio file.
You may change the Project Rate at any time. Doing so does not affect the actual tracks in any way, but it does affect the sample rate that they are played at.
Summary:
Each audio track has a sample rate. That’s the sample rate of the audio data in that track. I call this the “track rate” or “track sample rate”.
Each project has one sample rate. This is called the “Project Rate” and is shown in the lower left corner of the main Audacity window.
The Project Rate determines the sample rate for recording, playback, generating audio, and export.
So if you resample a track from from 88200 Hz to 96000 Hz will the newly upsampled track contain the same information as if you recorded that track at 96000 Hz?
I understand that the difference in quality is pretty much negligible but I want all my LP recordings to be recorded at the same sample rate
The frequency range in the digital audio is limited by the sample rate. Audio frequencies above half of the sample rate cannot be represented.
Example: With a sample rate of 44100 Hz, the available audio frequency range has an upper limit of 22050 Hz.
Example: With a sample rate of 88200 Hz, the available audio frequency range has an upper limit of 44100 Hz.
Example: With a sample rate of 96000 Hz, the available audio frequency range has an upper limit of 48000 Hz.
Resampling a high sample rate track to a lower sample rate will remove any frequencies that are above half of the new sample rate.
Example: If you have a track with a sample rate of 96000 Hz, there may be frequencies up to 48000 Hz. If you resample the track to 48000 Hz, the frequency limit is reduced to 22050 Hz, so any frequencies that were present in the original that were above 22050 Hz are lost.
Resampling from a lower sample rate to a higher sample rate does NOT add any additional frequencies. Although 96000 Hz sample rate supports frequencies up to 48000 Hz, if the audio doesn’t have very high audio frequencies, resampling to a higher rate will not magically add them.
Note that it is rare for adults to be able to hear frequencies much above 16000 Hz, and extremely rare for anyone to hear anything above 20000 Hz. Higher frequencies are off the scale for human ears and inaudible.
(Under scientific test conditions, it has been demonstrated that a few individuals are able to detect the presence of sounds that are a little over 20000 Hz, though in real world conditions it is fair to say that such high frequencies are totally inaudible to everyone, and for most people the upper frequency hearing limit is significantly lower than 20000 Hz.)