-Record the audio as wav with PCM signed 16 Bit, 48000 Hz, Mono (preferable) else stereo.
Yes. Edit → Preferences → Quality. (That may not be important since you are going to downsample anyway).
Record high quality
The quality depends on your hardware and your acoustic environment. Audacity just “captures” the digital audio stream and sends it to your hard drive.
mix down to 8Khz mono
There is a drop-down box in the lower left of the Audacity Window to set your project sample rate. At the top, there is a menu button that looks like a microphone. There you can select your input and one or two channels.
-Filter out audio below 300 Hz and above 3000 Hz
Effect → High-Pass Filter at 300Hz, Effect → Low-Pass filter at 3000Hz*
-Keep volume levels between -6 and -9db
Effect → Amplify. The Amplify effect allows you to set your peak levels.** (Targeting a particular average level is trickier)
-Wav PCM Signed Mono
That’s NOT standard. 8-bit WAV files are unsigned. (16-bit WAV files are signed.) You can create a RAW 8-bit signed PCM file, but it won’t have the WAV header. Export → Other Compressed Files → Options…
16-bits X 8000Hz = 128 kbps so that happens automatically.
Note that the filter “cutoff” frequency is defined as the -3dB point… So if you need to filter out everything at 300Hz and below, you’ll need to set the cutoff frequency slight above 300Hz (and slight below 3000Hz).
** With 8-bits, you don’t have a whole lot of resolution and with peaks at -6 or -9dB you are not using all of the bits and “throwing away” resolution.
Thank you so much for your kind reply.
I have followed your steps and recorded the audio accordingly. How should I check whether the sound recorded by me is matching the specifications. I am uploading the file that i have recorded.
Kindly help !!!
If you right-click over the file > Properties, Windows may or may not confirm the bit depth. You can see the sample rate in Hz if you import the file into Audacity then look above Mute / Solo to left of the waves. The bit depth there is the bit depth Audacity uses to read the data, not the actual bit depth of the file.
you still have content below 300 Hz and above 3000 Hz, including a relatively high peak at 161 Hz. You will need to run High Pass and Low Pass again with cutoff frequency further above 300 Hz (and further below 3000 Hz).