There are several methods for diagnosing hypernasality.

- A speech therapist listens to and records the child while analysing perceptual speech. In hypernasality, the child cannot produce oral sounds (vowels and consonants) correctly. Only the nasal sounds can be correctly produced. A hearing test is also desirable.

- A mirror is held beneath the nose while the child pronounces the vowels. Nasal air escape, and thus hypernasality, is indicated if the mirror fogs up.

- A pressure-flow technique is used to measure velopharyngeal orifice area during the speech. The patient must be at least three to four years old.

- A video nasopharyngeal endoscopy observes velopharyngeal function, movements of the soft palate, and pharyngeal walls. It utilises a very small scope placed in the back of the nasal cavity. The doctor will then ask the child to say a few words. The patient must be at least three to four years old to ensure cooperation.

- A cinefluoroscopy gives dynamic visualisation and can easier be applied to younger children, though it has the disadvantage of exposing the patient to radiation.

- A nasometer calculates the ratio of nasality. The patient wears a headset, where the oral and nasal cavities are separated by a plate. On both sides of the plate are microphones. The ratio calculated by the nasometer indicates the amount of nasality, with a higher ratio indicating more nasality.

Hypernasality is generally segmented into so-called 'resonance' effects in vowels and some voiced or sonorant consonants and the effects of excess nasal airflow during those consonants requiring a buildup of oral air pressure, such as stop consonants (as /p/) or sibilants (as /s/). The latter nasal airflow problem is termed 'nasal emission', and acts to prevent the buildup of air pressure and thus prevent the normal production of the consonant. In testing for resonance effects without the aid of technology, speech pathologists are asked to rate the speech by listening to a recorded sentence or paragraph, though there is much variability in such subjective ratings, for at least two reasons. First, the acoustic effect of a given velopharyngeal opening varies greatly depending on the degree of occlusion of the nasal passageways. (This is the reason why a stuffy nose from an allergy or cold will sound more nasal than when the nose is clear.) Secondly, for many persons with hypernasal speech, especially hearing impaired, there are also mispronunciations of the articulation of the vowels. It is extremely difficult to separate the acoustic effects of hypernasality from the acoustic effects of mispronounced vowels (examples). Of course, in speech training of the hearing impaired, there is little possibility of making nasality judgments aurally, and holding a finger to the side of the nose, to feel voice frequency vibration, is sometimes recommended.

In psychiatry, stilted speech or pedantic speech is communication characterized by situationally inappropriate formality. This formality can be expressed both through abnormal prosody as well as speech content that is "inappropriately pompous, legalistic, philosophical, or quaint". Often, such speech can act as evidence for autism spectrum disorder (ASD) or a thought disorder, a common symptom in schizophrenia or schizotypal personality disorder.

To diagnose stilted speech, researchers have previously looked for the following characteristics:

- speech conveying more information than necessary

- vocabulary and grammar expected from formal writing rather than conversational speech

- unneeded repetition or corrections

While literal and long-winded word content is often the most identifiable feature of stilted speech, such speech often displays irregular prosody, especially in resonance. Often, the loudness, pitch, rate, and nasality of pedantic speech vary from normal speech, resulting in the perception of pedantic or stilted speaking. For example, overly loud or high-pitched speech can come across to listeners as overly forceful while slow or nasal speech creates an impression of condescension.

These attributions, which are commonly found in patients with ASD, partially account for why stilted speech has been considered a diagnostic criteria for the disorder. Stilted speech, along with atypical intonation, semantic drift, terseness, and perseveration, are all qualities known to be commonly impaired during conversation with adolescents on the autistic spectrum. Often, stilted speech found in children with ASD will also be especially stereotypic or rehearsed.

Patients with schizophrenia are also known to experience stilted speech. This symptom is attributed to both an inability to access more commonly used words and a difficulty understanding pragmatics, or the relationship between language and context. However, stilted speech appears as less common symptom compared to a certain number of other symptoms of the psychosis (Adler "et al" 1999). This element of cognitive disorder is also exhibited as a symptom in the narcissistic personality disorder (Akhtar & Thomson 1982).

In its more common usage, "stilted speech" is a term used to describe overly-formal, unnatural-sounding speech.