Snd is a sound editor modelled loosely after Emacs.  It is highly
programmable, supports a variety of audio and sample file formats,
includes a complete implementation of Common Lisp Music (CLM), can be
run sans GUI as a scripting engine, and more.

This SlackBuild configures Snd to use Scheme (s7), ALSA, and Motif.
But using GTK3 instead of Motif is also easy.
  GTK=yes sh ./snd.SlackBuild

To enable support for OpenGL spectrogram rendering:
  OPENGL=yes sh ./snd.SlackBuild