One of the core beliefs of those making a case for singing in the school curriculum is its complementarity to the playing of instruments. According to Kemp, being musical through use of the voice, relying as it does on action within, and unseen, is less cognitive and more subjective than knowing through instruments.  Some kind of subjective-objective balance is proposed.
The voice within, the instrument without.
Well, there’s a compact rationale for you.
Many vocal advocates highly prize the power of silent singing (sub-vocalizing), the thinking and feeling of music in mind – (body), and thought of as a foundational form of listening.
But what about the art of Lip sync?
‘Lip sync, lip-sync, lip-synch (short for lip synchronization) is a technical term for matching lip movements with sung or spoken vocals. The term can refer to any of a number of different techniques and processes, in the context of live performances and recordings.’ 
Here the voice is disembodied, the lip syncer is wearing a mask.
We could think of this as sub-vocalizing with lips moving, a sort of musical ventriloquism. Much listening required in this, much attentive listening. 
But now let’s introduce that much neglected instrument, the kazoo patented in 1883. This is an instrument through which humming and other vocalise is transformed into instrumental timbres. Is there a kazoo-ukelele orchestra out there? 
Sub-vocalization, lip-synchronization and kazoo playing offer in their different ways forms of intensive listening experience and, of course, the experience of thinking in sound. Thinking in sound – is this what is meant by music as the target language? ‘The target language’ – what an unfortunate expression that is.
 Kemp, A. E. (1990) Kinaesthesia and development in music micro-technology, British Journal of Music Education, 7, 223-229.
 Lip syncing is a cultural practice and I’m not sure about reducing it to psychological behaviour. What do you think?