Reddit mentions of Auditory Neuroscience: Making Sense of Sound (The MIT Press)

I like this question.

Beginner:

• Neuroscience: Exploring the Brain (I don't like this text, but it's fairly accessible to beginners.)
  
  
• Auditory Neuroscience
  
  
• Musicophilia
  
  Student:
  
  
• Neuroscience
  
  
• MATLAB for Neuroscientists
  
  
• An Introduction to the Psychology/Physiology of Hearing (sorry, that was cheating)
  
  Expert:
  
  
• Principles of Neural Science
  
  
• Spikes
  
  
• Signal Detection Theory and Psychophysics
  

I don't think there's a definite answer to this yet. But it's certainly true that many auditory neurons, even to cortical level, respond to a narrow range of periodicities of the input waveform (see, e.g. chapter three of this book). I think it is therefore reasonable to speculate that harmoniousness is something to do with different frequencies exciting neurons of the same characteristic frequency. For example, a tone with period T also has period 2T, so frequencies an octave apart would stimulate the same neurons.