There is no agreement in the present day neurology on the human senses, their number, role, and classification. Various language cultures would have the secondary brain receptive areas for gnostic regions; some would try to find one gnostic area to explain the whole brain. It’s gotta be good for one to know where they are for one to know what they are speaking about. ;)
The mixup becomes serious when it comes to the tongue. Touch happens to be associated with exteroceptors. The tongue may be better off in the mouth.
I am definitely not an advocate of sorting out everything about the human being, especially in any absolute manner. My thing here is about the phonetic placement methods in speech training or re-training. Obviously, if the thing works for you, you go for it. All along, think whose tongue your tongue really is. My tongue has got to be mine to be my tongue, to me.
This is where some attention for the dispraised proprioception might help. Phonetic placement would put most emphasis on touch. There are touch receptors in the tongue and they are very sensitive. Yet, being touched in the tongue can be invasive and unpleasant (discomfort may make language learning a fiasco).
Speaking gives a much different sensation from that of being touched in the tongue. Further, however the tongue may touch the teeth or the palate for some speech sounds – what about vowels? They may be pronounced without occlusion.
The tricky part about hearing is that it is part intracranial. Most kids produce ‘crazy’ and loud sounds, which could be actually part practicing this inner hearing capacity. It is not gone with adulthood.
Speaking deliberately quiet with ear plugs – easy, your eardrums are not gonna like touch, either – can help realize the ‘inner ear’. A still better environment could be water. Just remember to switch the jacuzzi off and keep your head comfortably supported, obviously your face above the water and your ears in it. Full swimsuit, you can take the goggles off should you want to do some reading. I could also ‘sell’ here the laziest way to swim in the world ever. You can lie your back on the water just minding to hold some air in your lungs (and breathing, of course). It is going to keep you on the surface of a quiet lake. Whisper is good for the more advanced. :)
Vowels happen to be low, mid, and high. Vowel height seems to have given rise to some of the differences in contemporary interpretations of Latin. According to one of the schools, your read the letter /c/ as [k] before low vowel letter representations (please feel welcome to see ‘The game of the ziggurat’). The contemporary ‘aftermath’ could be the way people say /cat/, /cost/, /coast/, etc. Before the mid and high vowel letter representations, you’d pronounce /c/ as [c] or [ts], dependent on transcription.
This stipulated ancient Latin speech sound would be similar to the way you say /tsar/ in English. German has it in /zeit/, ‘time’; American has it in /zeitgeist/, ‘the general intellectual, etc. climate of an era’. Again, the contemporary ‘aftereffect’ could be the way people say /cell/, /cinema/, or /cycle/, there being a degree of overlap between /y/ and /i/ in Modern English. Another school would have the Latin /c/ for [k] regardless of aftereffects. ;)
Nature has had it that the brain needs to come before the tongue in speech. The phonetic placement method could not work for me. Generally, practicing with focus on hearing and tongue position can bring better effects.
‘Travelers in Grammar – The Whole Journey’, http://travelingrammar.com/.
 The disputed /u/ is reported to have developed from /v/. The Latin /c/ may be considered to have been interpreted as /k/ before non-vowel letter symbols, too. The Latin ‘caelum’, ‘sky’, ‘heaven’ would be a [tselum] or, more contemporarily, [tchelum]. The two letters stand for one sound, the mid [e]. The mid [e] also happened to be spelled as /oe/. According to older versions of the Latin alphabet, /cujus/ or /cuius/ ‘(of) which’, ‘whose’, ‘who’, ‘what’ – dependent on the time and epoch – could be transcribed as /cvivs/, for example. Latin alphabet evolved over ages, its knowledge belonging initially mostly with augurs, who kept things complicated enough.