Well it used to be the case with Puppy Linux that you couldn't monitor the recording sound level via, say, arecord --vv /dev/null, command at the same time as running a program like Precord. That's was because only one app could access alsa, including the recording program arecord at the same time. Some apps, such as mhwaveedit, tapped into alsa more directly (via compiled C) so could provide VU level meter, but was not possible with simple scripts such as Precord using underlying commandline utilities. However... if you have pulseaudio, that is no longer an issue. So you can, for example, record audio using the likes of Precord, whilst in another terminal running command:
arecord -vv /dev/null
Or if you want more sophistication you might like to use a wee oscilloscope program like xoscope, which works very nicely indeed:
http://xoscope.sourceforge.net/
which I'm currently playing with in WDL_Arch64 as well as trying out more sophisticated "WaveForms" by diligent:
https://digilent.com/shop/software/digilent-waveforms/
https://digilent.com/reference/software ... ms-3/start
WaveForms is free download and works (free to use it seems) with SoundCard simply by selecting that as input, but much heftier (slow) program than xoscope since Waveforms using Qt5 and more... WaveForms is interesting though since it provides many tools in addition to oscilloscope, including Function Generator (and also a SDK for software development with the likes of Python).