bchunk converts a CD image in a ".bin / .cue" format (sometimes ".raw / .cue") to a set of .iso and .cdr tracks.
.iso is for the data portions of the disc and
.cdr is the audio data. There can be both on so called "mixed mode" CDs.
The .cdr tracks are in the native CD audio format. They can be either written on a CD-R using cdrecord ‐audio, or converted to WAV (or any other sound format for that matter) using sox.
and, if you don't like the
-w Makes binchunker write audio tracks in WAV format
You don't need an ISO image to write an audio CD. I don't know what you want to accomplish other than this, so probably you are asking the "wrong" question. You can write the audio CD information to disc with e.g.
wodim which is an available package in Ubuntu, or Brasero which is the main graphical burning program in Ubuntu, or probably in many other ways.