Can I change the sample rate of a recording

I have several Audiobooks that I have downloaded from various newsgroups in MP3 format. I normally play the books on my Samsung Galaxy S3 using the Smart AudioBook player. One of the features it has is the ability to play the books at speeds faster than normal, however for this function to work the files must have a sample rate of 44.1K. I’ve encountered several books where I can only play at normal speed.

How do I determine the sample rate the file currently has?
Using Audacity or any other software can I change the sample rate? If yes, how?

Yes, but. Audacity resamples internally and you can export a new file at whatever sample rate or compression you want. Change the show sample rate with the little window lower left.

That’s the good news. In order to retain the sound quality of the original show, you can’t compress it any more. No more MP3. You can export it as a very, very high quality MP3 or a WAV, AIFF, FLAC, or one of those. What you can’t do is go back to the tiny, efficient file that the show had originally. The sound damage is likely to be terrible.

Compressed files get progressively more damaged as you do production.


Right click on the files and look at the “properties” tab.

and you “think” that is because they are not 44.1 kHz, or you “know” that is because they are not 44.1 kHz?

and you “think” that is because they are not 44.1 kHz, or you “know” that is because they are not 44.1 kHz?

Per the author of the player it must be 44.1 kHz.

I forgot to ask when changing the sample rate can I do a group of files at the same time? Some of the books have over 200 MP3 files.

I’m not trying to compress the file anymore than it currently is or I don’t really care if it gets bigger. My phone has 32GB and if necessary I can add another 32GB and on my current desktop I have about 19 TB of space. Also I don’t need to convert it to another format all of my players (PC and Phone) play mp3.

What sample rate are they?

The only practical way to do multiple sample rate conversions is to multiple import the files, change the project rate bottom left, then FIle > Export Multiple.

Do you want to increase the pitch of the audio when you speed it up, or not? You could do either in Audacity, as an unattended batch process, but you could not change the sample rate as well. Effect > Change Speed will change the pitch as well as the speed, Effect > Change Tempo will not. See .


In Win7 when I right-click, select properties and then view the details tab I do NOT see anything about sample rate, I do see bit rate (in the Audio section) but this is not sample rate.

I’m not really sure what the sample rate of the files are. In Windows the properties does not display the sample rate or at least not on my Win7 system.

In Audacity when I open the files, in the bottom left corner of the window the Project Rate is 44100 Hz, does this mean that the sample rate of the files (I opened all the MP3 files in the folder for the book I’m currently working with)

I see that the files are MONO, I think one of the other requirements might be that the file must be stero. I just tried a test with three file and used Joint Stereo (whatever this is) and still I cannot change the speed in the playback app on the phone.

Sorry, you’re correct, I keep forgetting how limited Windows is.
There’s a program called MediaInfo that will be able to tell you
(If you don’t want to install the “bundle ware” that is included with MediaInfo, pay attention to the options when you install it or use the “without installer” version. See here for more information:

I have some progress but not success at this time

MediaInfo has changed the installer. As you install you will get a window titled “AVG Security Toolbar” on this screen you can select “Custom Installation”, when selected the default is to NOT install any of the AVG software (this is what I selected in that I already have Kaspersky Internet Security installed).

I also received an email from the author of Smart AudioBook Player and the file must be 44100 Hz and Stereo. When I use Audacity to export the files I noticed that it defaulted to “Joint Stereo” or I could select Stereo. I could not find anything that explained Joint Stereo but I ran a test with both options. Nether worked in SAP. I used MediaPlayer to display the info about my original file (44100, mono) and the exported file (44100 - should be stereo) but I don’t see where MediaInfo tells me if it is Mono or Stereo.

I went back to Audacity and open one of the converted Stereo files and it is still Mono thus the export did not change it from Mono to Stereo. I realize that the two chanels would be the same but it would still be stereo as far as SAP is concerned. Did I do something wrong in the export? I have three files I’m testing with, I select File > Export Multiple > on the Export Multiple window I selected MP3 as the output (BTW my source file is MP3, I clicked on the Options button and selected Mit Rate of 48 kbps and for the channel Mode I selected Stereo), my file location, Name files (I left the default of Using Label/Track Name), I also left the button for Tracks selected.

The “stereo / joint stereo” options in MP3 export have no effect if the audio that you are exporting is mono.

It is easy to recognise a mono track once it is in Audacity because it only has one channel (only one waveform), whereas as stereo track shows 2 channels (2 waveforms) one above the other.

To make a mono track into a 2 channel track:

  • Select the track (double click on it) and then Duplicate it (Edit menu or Ctrl+D).
  • Click on the name of the upper track and from the drop down menu select “Make Stereo Track”.

When you export it will create a 2 channel MP3.

MediaInfo should show the “number of channels”.

Joint Stereo will probably give you better sound quality, but you will need to check if it is compatible with your Smart AudioBook Player.

Does SAP change speed with complete flexibility - you can choose +25% or - 5% or other choices?

As well as MediaInfo, I use dBPowerAmp on Win 7. dBPowerAmp adds its own “Audio Properties” sheet to Explorer Properties. However I do have “Audio sample rate” on the “Details” tab as well (but don’t have it on Win 7 on another computer that lacks dBPowerAmp and MediaInfo). Therefore I assume that one of those programs must modify the “Details” properties sheet.

MediaInfo gives the number of channels under “First audio stream”.

Audacity’s Project Rate only shows the sample rate of the file if that file created the first track in the project. So if the first MP3 you import into an empty project is not 44100 Hz, the Project Rate will change to that rate, and will not change again, so make sure the rate is 44100 Hz before you export.