"Neutral Unit" for tone sequences

[Emma M Duffy <emma.duffy676@xxxxxxxxx>]

Hello,

I am pursuing an undergraduate Honors thesis in the Speech, Language and 
Hearing Sciences department at my university. For our project, we will 
present to our subjects tone sequences with varying rhythmicity and then 
present to them tone sequences with changes in pitch. One goal that we 
have is to have our subjects reproduce these sequences with a “neutral 
unit” that removes (as much as possible) the influence of speech and 
phoneme articulation.  We are considering something like the schwa, or 
an 'eh' sound.  I would appreciate suggestions or ideas regarding what 
neutral units might be appropriate to use for our task to get around 
the “speech unit” issue.

Thank you for your help!
Emma Duffy