|Variable Pitch Pipe (from: Wikipedia)|
“[…] Their study has revealed that languages with a wide range of tone pitches are more prevalent in regions with high humidity levels. In contrast, languages with simpler tone pitches are mainly found in drier regions. This is explained by the fact that the vocal folds require a humid environment to produce the right tone.”
— via New Shelton we/dry
“[…] A person with poor pitch perception may be able to improve his or her ability to differentiate pitches or mimic them, but a person who is truly tone deaf may not have the capacity to improve whatsoever no matter how much he or she practices.
The level of exposure to music as a child may play a part, in that the brain may have reduced capacity for pitch mimicry. But this -- nor any other environmental factor -- doesn't account for tone deafness.
Tone deafness seems to be entirely hereditary, and identical twins score similarly when taking pitch tests. As we mentioned earlier, it's not the reception of the tone that is compromised, but the brain's processing of it.”
— Tom Scheve, How Stuff Works
“So, you'd think that a tone-deaf [Mandarin] Chinese [-speaking person] would be stuck. How can [she/] he tell the difference in speech between, say, ‘woman’ and ‘horse’ with only their distinct tones to distinguish the meanings?
Easily enough, it turns out. Mostly, he [/she] uses context and other language clues. Homonyms in Chinese (or English: 'I'm a little hoarse'), rarely confuse a listener — when heard in context. But also, it's easier to distinguish varying tones. Moreover, the tones we use in languages are coarse discriminators that even a disabled person can manage. To convey meaning differences, speech requires tone distinctions three to six times greater than melodies do for musical nuances.”
— April Holladay, USA Today