What are the secrets of an ‘ugly’ voice? Steps towards answers were provided in 2006 by Professor Johan Sundberg, (personal Chair (Emeritus) in Music Acoustics at the department of Speech Music and Hearing KTH Royal Institute of Technology, Stockholm), in his paper for Advances in Cognitive Psychology, 2006 • volume 2 • no 2-3 • 131-143.
“Timbral beauty is an important aspect of a singer’s voice, but certainly also elusive: what is beauty and from what does it emerge? Yet, the beauty of a voice is often striking, but perhaps, and even more so, the ugliness of some voices.”
Here’s a human example from the paper [ .wav format ]
And a synthesised example [ .wav format ]
See ‘The KTH Synthesis of Singing’ by Johan Sundberg