Preface

Japanese words have been romanized throughout this writeup.

In Japanese, phonoaesthetics are almost always written in hiragana. Among other things, this indicates their Japanese linguistic roots. They have been found as early as the Manyoushuu (万葉集) and early Heian women's literature. (Kaiser)

To quote Kaiser:

"In modern Japanese, phonoaesthetic Japanese (PJ) expressions are common in the informal register of speech; they are much less used in formal language. In writing, they are widely found in literature, but less in essays and even less in specialist articles, and are virtually absent from law codes and legal documents. In newspapers, they are infrequent in the politics and economics sections, but appear more often in the social pages. PJ items stike a chord with people's feelings, and are therefore widely used in the language of advertisements, but are also ubiquitous in comics, including many newly invented ones (for instance, to imitate the laughter or sound of anger of an extraterrestrial being) to supplement the pictures."
Kaiser, pp. 37

Phonoaesthetic Japanese

For the language learner, among the most confusing of phonoaesthetic Japanese is the use of the phenomime, a type of onomatopoeia which does not specifically refer to any audible or otherwise perceptible sound. How can one understand the meaning of a sound one cannot truly hear? And how can that inaudible sound be represented by language?

The phenomime is often used as an adverb in Japanese, sometimes using the special adverbial marker to (と) as a suffix. This form of adverbial use is unfamiliar to the native speaker of English, because English uses a myriad of verbs, many themselves onomatopoeiac. Japanese, on the other hand, tends to use one common, base verb and an assortment of phenomimes as adverbs.

Consider different kinds of the English verb walk below. (Koujien)

Kinds of walk
   Japanese      Japanese          English
  Phenomime        Verb             Verb                 

tobotobo         aruku          trudge		  
chokochoko       aruku          trot		  
noronoro         aruku          inch (along)
yoroyoro         aruku          stagger, stumble, shamble
furafura         aruku          shamble, teeter
burabura         aruku          stroll, loiter
zorozoro         aruku          swarm (in/out), cluster

In his textbook, Kaiser (2001) describes another type of phonoaesthetic, the psychomime. Although the difference between the above phenomime is fuzzy, and it is often considered to be a sub-type, psychomimes are used to express states of mind or emotion, while phenomimes are used to express an action, movement, or state. The simplest type of phonoaesthetic, the phonomime, mimics a natural sound. Most of the examples given by jprockwell above are phonomimes.

Here are examples of psychomimes being used as Japanese adverbs to express facial or body expressions, as well as emotional states and feelings. They often take the standard Japanese verb suru (する), do, and I have attempted to provide suitable verbs for their usage. Note that while the psychomimes are all linguistically adverbs, they often translate into different forms in English.

Facial / Body Expressions and Reactions

   Japanese      Japanese            English
  Psychomime       Verb             Expression                         

angurito           akeru         be open-mouthed with amazement
                                 eg. kuchi wo angurito akeru
bonyari            suru          be vacant, dull, sleepy
boutto             suru          be absent-midned
buzutto            suru          be sulky
deredere           suru          be spoony
doronto            suru          be dull (esp. eyes)
fufunto            suru          be huffy, turn up one's nose
gessori            suru          be disenheartened
gyotto             suru          be startled, shocked
gyorogyoro         saseru        roll one's eyes, glare
herahera           warau         gloat, smirk
jirijiro           miru          stare
kerotto            suru          behave as if nothing had happened,
                                 forget one's grievance
magomago           suru          get confused, be at a loss
majimaji(to)       suru          gaze at
muttsuri           shita         look sullen
                                 eg. muttsuri shita kao = a sullen face
nikoniko           warau         smile, beam
nyanya             warau         smirk, look pleased
nitanita           warau         grin
ninmari            warau         grin from ear to ear, look satisfied
pokanto            shita         blank-looking, vacant-looking
poutto             shita         depressed, disappointed, sad-looking

Emotional States or Feelings

   Japanese      Japanese            English
  Psychomime       Verb             Expression            

akkerakanto        suru          be vacant, distracted
dokidoki           suru          be anxious
gakkari            suru          feel downcast, dejected
hiyahiya           suru          be frightened, scared
hotto              suru          feel relieved
iraira             suru          be irritated, aggravated
jirijiri           suru          be irritated, impatient
mutto              suru          be annoyed, be angry
ukiuki             suru          feel elated
uttori             suru          be fascinated, rapt
wakuwaku           suru          be excited

Another common usage of the psychomime is to express different types of pain. The verb "itamu" (to be painful) may also be used in place of "suru".

Types of Pain
   Japanese      Japanese          English
  Psychomime       Verb             Expression                  

chikichiku        suru            sting, prick
gangan            suru            pounding, splitting (headache)
hirihiri          suru            tingle
jiinto            suru            numbing pain
kirikiri          suru            stabbing pain
piripiri          suru            sharp, biting pain
shikushiku        suru            gripping pain
zukizuki          suru            throb, smart

Being able to "hear" these inaudible sounds is probably a sign of having mastered the Japanese language.

If nothing else, being able to understand the concept of the Sound of Silence is very zen.

Afterword
I suppose it bears mentioning that the Japanese word for onomatopoeia is giseigo, based on three characters which mean "imitate", "voice", and "word".

Sources:

Genius Japanese-English Dictionary. Tokyo, Japan. Taishukan.
Kaiser, Stefan. (2001) Japanese Language II. Tokyo, Japan. Council of Local Authorities for International Relations.
Koujien, 5th ed.