PERCEPTUAL ANALYSIS OF SPEECH (INCLUDING SEGMENTAL AND SUPRASEGMENTAL ASPECTS AND INTELLIGIBILITY)

CONTENTS:

1.     INTRODUCTION:

·        PERCEPTUAL ANALYSIS

·        SEGMENTAL AND SUPRASEGMENTAL ASPECT

2.     PERCEPTUAL ANALYSIS OF SEGEMENTAL ASPECTS.

3.     PERCEPTUAL ANALYSIS OF INTELLIGIBILITY.

4.     PERCEPTUAL ANALYSIS OF SUPRA SEGMENTAL ASPECT.

5.     ADVANTAGES AND DISADVANTAGES OF PERCEPTUAL ANALYSIS.

6.     IMPORTANCE OF PERCEPTUAL ANALYSIS IN CLINICAL SET UP FOR DIAGNOSIS.

INTRODUCTION:

                Motor speech disorders can be analyzed in many ways, all of which contributes to their characterization and understanding.

                The methods can be categorized under two broad headings; perceptual and instrumental.

                  Perceptual methods are based primarily on the auditory-perceptual attributes of speech. They are the “Gold- standard” for clinical differential diagnosis, judgment of severity, many decisions about management, and the assessment of functional change.

                  But at the same time these perceptual analysis are unreliable for the judgment among clinician. It is difficult to quantify and cannot directly test hypothesis about patho physiology underlying perceived speech abnormalities. However it is unlikely that it will be replaced by other methods, however sophisticated, because the evaluation of a speech disorder always begins with a perceptual judgment that speech has changed or is abnormal or different in some way.

                  DAB (Darley, Aronson, Brown 1969, 1975) pioneered the modern use of auditory perceptual assessment to characterize the dysarthrias and to identify the clusters of salient perceptual characteristics that are associated with lesions in different portions of the central and peripheral nervous system.

SEGMENTAL AND SUPRA SEGMENTAL ASPECTS OF SPEECH

     

                  The speech mainly depends up on two aspects one segmental and other is supra segmental. These aspects are very important for correct production of speech.

SEGMENTAL ASPECTS OF SPEECH:

     Segmental aspects of speech includes

1.     Respiration

2.     Phonation

3.     Resonation

4.     Articulation

1.     Respiration

              Normal respiration is an important function in delivering a normal speech. While speaking the inhalation will be much more quick and bit more deep. After each inhalation the exhalation of the air should be controlled very precisely in order to maintain just the correct rate of airflow and the amount of pressure needed to “drive” the speech mechanism.

2.     Phonation:

                     

                       The larynx a delicate and very important part of speech mechanism is suspended in our neck beneath the hyoid bone (the only bone in our body which does not articulate with any other bone) and above the trachea (or wind pipe). The sound of human voice (phonation) is produced by paired vocal folds, one on the left side, and one on the right side, which lie within the major cartilage of larynx, the thyroid cartilage.

3.     Resonation:

                    All voices have sound energy present over a very wide range of frequencies. Normally there are greater amounts of energy present in the fundamental and lower frequency harmonics than in the higher frequencies.

                    The process of resonation enables us to produce recognizably different vowels and some consonant sounds. By altering configurations of our throat and mouth cavities through movement of tongue, lips, and jaw, we create resonators that will emphasize energy at some frequencies and suppress energy at others.

                     Above the pharynx and oral cavity is the nasal cavity a resonating chamber that also can add to (or subtract from) the original character of glottal tone. In producing the nasal consonants of course nasal resonance is an essential and distinguishing feature.

4.     Articulation:

                           

                           The articulators of speech sounds, the consonants, vowels and diphthongs that are the basic phonemic elements of our language, demands incredibly intricate coordination of the tongue, lips, mandible, and velum. And the movements of these structures occur in synchrony with those of the respiratory and phonatory systems.

SUPRASEGMENTAL ASPECTS OF SPEECH:

                            Suprasegmentals are characteristics of speech that involves larger units, such as syllables, words, phrases, or sentences. Among the suprasegmentals are stress, intonation, loudness, pitch level, juncture, and speaking rate. Briefly defined, the suprasegmentals also called prosodies, or prosodic features, are properties of speech that have a domain larger than single segment.

STRESS:  Stress refers to the degree of effort, prominence, or importance given to some part of an utterance.

                             Eg: Be sure to take the RED car

INTONATION:  Intonation is the vocal pitch contour of an utterance, that is, the way in which the fundamental frequency changes from syllable to syllable and even from segment to segment.

LOUDNESS:  Loudness is related to sound intensity or to the amount of vocal effort that a speaker uses.

PITCH LEVEL: Pitch level is the average pitch of a speaker’s voice and relates to the mean of the fundamental frequency of an utterance.

JUNCTURE:  Juncture sometimes called “Vocal punctuation”, is a combination of intonation, pausing and other suprasegmentals to mark special distinctions in speech or to express certain grammatical divisions.

                           Eg: “Let’s eat, Grandma.”

SPEAKING RATE:  The rate of speaking is usually measured in words per second, syllables per second, or phonemes per second. As speaking rate increases, segment duration generally become shorter, with some segment affected more than others.

HISTORY TAKING:

                                       A written case history is starting point of understanding the client’s and their communicative problems. A case history enables the clinician to anticipate those areas that will require assessment.

PERCEPTUAL ANALYSIS OF SEGMENTAL ASPECTS

     The segmental aspects of speech include

        Respiration

        Phonation

        Articulation

        Resonation

        Respiration:

                   Evaluation of respiration involves assessment of patient’s ability

      to control the respiratory mechanism for speaking as well as for

      vegetative purposes. The general diagnostic question that needs to be

      addressed is “Does this patient has sufficient air supply and

      neuromuscular control of the respiratory mechanism to communicate

      effectively?”

Observation of the patient’s use of respiratory system

           An in-depth respiratory diagnosis is not required for majority of patients with voice disorders. Many times the question whether the patient is using the respiratory system efficiently enough to effect functional communication can be answered through careful observation while he or she performs the following four tasks

1.     Read aloud the standard paragraph.

               For e.g. Rainbow passage

a)     In persons with normal voice, terminations of phrases or sentences coincide with the termination of exhalation.

b)    Some patients with voice disorders attempts to continue speaking past the point where there is sufficient airflow to

effect efficient phonation, thus resulting in an increase in laryngeal tension.

2.     Perform a task of sustained vowel production.

           Patient should be able to produce an adequate amount of air and

be able to sustain phonation long enough to communicate efficiently.

3.     Perform a task of sustained /s/ and /z/ productions.

4.     Perform a task of endurance of sustained speech production.

Evaluation of respiration should be done on the patient during quiet breathing and few non-speech activities.

Breathing posture should be observed in quiet breathing conditions. If

breathing posture is not normal; it should be noticed whether the patient is

slouched in the chair or bent forward or to the side, whether the patient tend to move towards abnormal posture in a chair of wheel chair, and to come back to a normal posture whether an additional effort or assistance is required. Is the head dropped forward or does it rest on the chest.                                                             

Whether the patient is braced in a wheel chair to maintain the normal posture. Respiratory support for speech is being reduced due to all these abnormal posture.

                    The information about insufficient breath at rest, during physical exertion or during speech (i.e. whether the breathing is rapid, shallow or labored) should be obtained.

                    The pattern of breathing should be taken in to consideration. Adequate thoracic and abdominal movements also should be checked.

                     Whether secondaries such as shoulder movements, neck extension are present.

                     Irregularity in breathing rate should be taken in to consideration.

        Phonation:

Over view of assessment

History of client

               History of client should be taken with the help of written case history, interview and from the information from other professionals.

Contributing factors:

             

              Environmental and behavioral factors medical and neurological factors. Motivation and concern.

Assessment of voice:

Pitch: Pitch of the person should be checked for high, low or normal pitch. Pitch breaks and inflections should be evaluated.

Loudness: It is important to assess whether the voice is too loud, soft or normal. Evaluation for Aphonia (Intermittent/continuous) and Inflection in the voice will have to be done.

Quality: Assessment of voice should be done to check the quality that is whether the voice is normal, harsh, breathy, and hoarse.

Procedure:

Screening

Serial tasks

Oral reading

Speech sampling

Maximum phonation duration

S/Z ratio

Velopharyngeal function

Stimulability of improved voice

Use of instrumentation

Oro-facial examination

Hearing assessment

Determination of diagnosis

Providing information [Written report, interview etc.]

Screening:

                  A screen for voice disorders can be accomplished with a few quick and easy tasks. For example, have the client imitate words or phrases, count, recite the alphabet, read a short passage or talk conversationally. Wilson (1987) recommended these four steps to screen children for voice disorders:

1.     Count from 1 to 10.

2.     Read orally for one minute.

3.     Produce continuous speech for one minute.

4.     Prolong the following vowels for five seconds each:                         /a/, /i/, /u/ and /ae/.

This sample is then evaluated according to the screening guidelines known as Buffalo-voice profile system which is given by D.K Wilson (1987).

The Buffalo voice profile system:

Author: D.K Wilson

                   This system provides a criteria and profile for rating the parameters of voice. In Buffalo voice profile evaluate 12 parameters of voice. In that mainly they consider four parameters for assessment. They are Laryngeal tone, Pitch, Loudness and Nasal resonance. They classified variation from the normal in to three they are Slight, Moderate, Severe variations.

The screening procedure from the Boone voice program for children (Boone, 1986) is also useful. Boone utilizes three rating scales to evaluate the basic parameters of voice. If any response not scored as normal, the client fails the screen and referred for a complete voice evaluation.

                    In three point rating scale Pitch, Loudness, Quality, Nasal resonance and Oral resonance are the categories which is to be checked and according to performance it is separated as  –ve to N to +ve in which –ve is too low, +ve is too high and N is normal.

Buffalo voice profile:

1.     Laryngeal tone

         Normal

    Breathy

    Harsh

    Hoarse

2.     Laryngeal tension

Normal

Hyper tension

Hypo tension

3.     Vocal abuse

Present/absent

4.     Loudness

Normal/too loud/too soft

5.     Pitch

Normal/high/low

6.     Vocal inflection

Normal/monotone/excessive

7.     Pitch breaks

None/amount of pitch breaks

8.     Diplophonia

Present/absent

9.     Resonance

Normal/hyper nasal/hypo nasal

10.                        Nasal emission

Present/absent

11.                        Rate of speech

Normal/fast/slow

12.                        Overall voice efficiency

Adequate/inadequate

Seven point rating scale is used to evaluate

1-4 slight variation

4-7 moderate variation

7 severe variations

GRBAS rating scale:

Author: Hirano, 1981

                    This test is used to check the various parameters in pathological voice cases.

1.     4 point rating scale.

2.     5 parameters; they are mainly Grade, Rough, Breathy, Asthenia and strain

                     For each dimension a score of 0 to 3 is used, where ‘0’ represents non hoarse or normal and ‘3’ represents extreme severity. Together these individual ratings combine to form a profile of the patient’s voice quality.

        Articulation:

               Normal articulation is a series of complex actions. Accurate articulation requires exact placement sequencing, timing, direction and force of articulation. These occur simultaneously with precise air stream alteration, initiation or halation of phonation and velopharyngeal action.

              Articulation problems results from organic or functional etiologies.

               The primary purposes of an assessment of articulation and phonological processes include:

 Describing the articulatory or phonological development and status of the client.

 Determining whether the individual’s speech sufficiently deviate from the normal expectations to warrant concern or intervention.

 Identifying factors that relate to the presence or maintenance of the speech disorder.

 Making prognostic judgments about change with and with out intervention.

 Monitoring changes in articulatory and phonological abilities and performance across time. (Adapted from Bernthal and Bankson 1988).

History of the client:

               

              History of the client should be taken with the help of written case history, interview and from the information from the other professional.

              Information about hearing ability of client should be available. Presence of any medical or neurological factors should be revealed out. Dentition of the client should be checked. Maturation and motor development should be checked.

Assessment procedure for articulation and phonological process include:

Screening

Articulation tests

Speech sampling

Stimulability of errors

In the analysis,

             Number of errors should be counted. Error types such as substitutions, omissions, distortions, additions should be analyzed directly from the client or from the speech sample. Consistency of errors should be noted. Intelligibility rate of speech should be assessed. Oro-facial examination should be done.

             In the case of children who are having cleft palate articulation, resonance and intelligibility should be checked.

             Perceptual speech assessment is central to the evaluation of speech outcomes associated with cleft palate and velopharyngeal dysfunction.

                  In the analysis of articulation disorders the articulatory system should be assessed in the state of rest, during movement and speech.

Face at rest:

-         Symmetry/ Asymmetry.

-         Expressionless/ Mask like/ Unblinking.

-         Abnormal spontaneous involuntary movements.

-         Deviation of lips.

Face at sustained posture:

-         Strength

-         Speed             Application to lip rounding

-         Range             retraction, puffing, puckering.

-         Steadiness

-         Tone

-         Accuracy    

Assessment of articulatory structures:

Appearance:

Lips should be checked for symmetry at rest.

Tongue should be checked for its size, surface and frenulum, tongue thrust.

Jaw should be checked for occlusion, size, and symmetry and for hanging down.

Teeth should be checked for alignment, symmetry, missing teeth and bite.

Hard palate: high arched symmetry and any organic pathology.

Soft palate:   symmetry, bifid uvula, absence of uvula and any other organic pathology.

Function:

Lips: Checking for protrusion, retraction, rounding, and puffing cheeks and bite lower lip.

Tongue: Checking for upward downward movement, lateral movements, tongue to cheek strength, lateral movements with in the mouth.

Jaw: Checking for clenching, chewing, lateral movements, upward and downward movements.

Soft palate: Checking upward and downward movements during phonation, gag reflex.

Alternate motion rate (AMR):

               AMRs, or diadachokinetic rates, are very useful for determining the speed and regularity movements of the jaws, lips and anterior and posterior tongue. They also permit assessment of articulatory precision, the adequacy of velopharyngeal closure, and respiratory and phonatory support for sustaining the task. These latter observations are usually secondary. “The primary value of AMRs is for assessing speed and regularity of rapid, repetitive articulatory movements”.

               The patient should be instructed to take a breath and repeat “puh-puh-puh” for as long and steadily he can. This should be followed by a 2 to 3 second example by the clinician. Patient can be told to stop when the sample is sufficient for clinical judgments.

               When repetitions of “puh” are completed the patient should be asked to repeat the task for “tuh” and “kuh”. AMRs for other consonant-vowel (CV) syllable can be pursued if other places and manner of articulation are of interest.

Sequential motion rate (SMR):

               SMR is a measure of ability to move quickly and in proper sequence from one articulatory position to another. Relative to AMRs, sequencing demands for SMRs are heavy; for this reason, “SMRs are particularly useful when Apraxia of speech is suspected”.

            The patient should be asked to take a deep breath and repeat “puh-tuh-kuh” over and over again until the clinician tells the client to stop. This should be allowed by 2 to 3 second example by the clinician. Some people need reinstruction in the sequence and slow or unison practice is sometimes necessary for the task to be grasped. When the sequence cannot be learned, repetition of “buttercup, buttercup, buttercup….” is acceptable, but the meaningfulness of the word makes it a simpler task than puh-tuh-kuh.

Articulation during speech:

          The misarticulation of phoneme of a word is assessed using standardized test materials such as picture articulation tests, Kannada articulation tests.

           Main four misarticulation types are obtained from the tests

a)     Substitution

b)    Omission

c)     Distortion        SODA

d)    Addition

The misarticulated sound is marked in initial, medial and final position.

Speech sampling is especially important for accurately diagnosing disorders of speech sound production. After obtaining a speech sample, analysis should be done with a focus of following behaviors.

 Number of errors

 Error types

 Consistency of errors between the speech sample and the articulation tests with in the same speech sample, and between different speech samples.

 Correctly produced sounds

 Intelligibility

 Speech rate

 Prosody

Articulation screening tests:

              

                   Frequently, a clinician will do a screening to determine if a more comprehensive assessment of this nature is warranted. Screening procedures are not designed to determine the need for the direction of therapy, but rather to differentiate the individuals who merit further evaluation from those for whom further evaluation is not indicated. Typical screening situations might include

1.     Screening children at a pre-school or “Kindergarten round up” to determine whether they have age appropriate phonological skills.

2.     Screening children in grade 3 (by which time maturation should have resolved most developmental errors).

3.     Screening college students preparing for occupation, such as teaching or broadcast journalism, which require certain speech performance standards.

4.     Screening the phonological status of referred children and adults for a suspected communication impairment.

                     In screening, individuals are not identified as candidates for therapy but rather are simply identified as needing further assessment. Instruments used for screening consists of a limited sampling of speech sound productions, which can usually be administered in five minutes or less. Screening measures can be categorized as informal or formal.

Informal screening measures:

                      Informal screening measures are usually devised by the examiner and are tailored to the population being screened. For example, with a group of kindergarten children, the examiner might ask each child to

1.     State his or her name and address.

2.     Count to ten; name the days of week.

3.     Tell about a television show.

          If the subjects are adults, the examiner might ask them

 to do one or both of the following:

1.     Frequently misarticulated sounds, such as /s/, /r/, /l/, and /θ/.

    For e.g. “I saw sally at her seaside house; Rob ran around the

    orange car.”

2.     Read a passage with a representative sample of English speech sounds such as the “Grandfather passage” or the “Rainbow passage”.

                Criterion for failures of informal screening is usually

determined by the examiner. An often used rate of thump is “If in doubt, refer”. In other words if one suspects that the client’s speech sound system is not appropriate for his or her age and/or language community, one should refer for a more complete assessment.

                     Formal screening measures include published elicitation procedures for which normative data and/or cut off scores are often available. These formal measures are of three types: (1) Tests that are part of a more comprehensive single- word articulation tests. (2) Tests designed solely for screening phonology and (3) Tests with screen phonology as well as other aspects of language. Tests designed explicitly for screening phonology are most frequently used when screening phonology is the primary goal.

The following are the formal phonology screening tests:-

Templin-Darley Screening Tests:- (Templin and Darley 1969).

                 This test consists of 50 items from Templin Darley test of articulation. Intention of this test is to elicit 22 single consonants, 26 consonant clusters, one vowel and one consonant- vowel combination. Norms and suggested cut off scores for children aged 3 through 8 years are provided.

Quick Screen of Phonology (QSP) (Bankson and Benthal, 1990).

                 This test consists of 28- picture naming items, with each word assessing sound in more than one content (usually initial and final). 23 phonemes are screened plus three consonant clusters. These items were selected because of their correlation with the overall norms of the Bankson-Benthal test of phonology. Percentile ranks and standard scores are provided for children ages 3; 0 through7; 11 years on the QSP.

Denver Articulation Screening Test (Drumwright 1971).

                       This instrument was designed specifically for screening phonological status in Algo, black and Mexican-American children. Responses are elicited imitatively. The examiner is asked to judge intelligibility on 4 point scales, with one being “easy to understand” and 4 being “can’t evaluate” children are ranked “normal to abnormal,” depending on composite articulation and intelligibility scores.

Screening Deep Test Articulation (McDonald, 1968).

                       This test consists of 90 items and is similar in form to the more completeDeep Test of articulation (McDonald, 1964a). It uses pairs of pictures to elicit ten productions of each nine commonly misarticulated consonants. This allows for production of specific consonants in a variety of contexts. The normative data provided for children from kindergarten through grade 3 are design to identify those children unlikely to develop mature articulation with out intervention.

Predictive Screening Test of Articulation (Van Riper and Erickson, 1969).

                        This test was designed not only for screening but also for predicting whether or not first-grade children are likely to correct their speech sound errors with out intervention. In other words it was designed both to indicate the need for additional testing for those who fail to obtain a cut-off score and to allow the examiner to make prognostic statements about the likelihood to self correction of speech sound errors. Stockman and McDonald (1980) reported that this test may have greater predictive value for those first graders who misarticulate specific consonant sounds since those sounds occur frequently in the test.

Fluharty Speech and Language Screening Test for Preschool Children (Fluharty, 1978).

                              This test was designed for children, ages 2 through 6 years. The phonology portion of the test uses 15 objects to elicit 19 target sounds. Some stimulus items are designed to assess a single segment; other items assess two sounds. Cut-off scores to indicate the need of further testing are included.

Preschool Language Scale (Zimmerman, Steiner, and Pond, 1979).

                               This test was designed for children, ages 1 through 7. The phonology portion of the test consists of 20 imitated words that test 18 speech sounds in initial, medial, and final word positions. Performance level expected for children are provided.

Iowa Pressure Articulation Test

                               The Iowa Pressure Consonant test is a subtest of the Templin-Darley Test of Articulation (Templin and Darley, 1969). It consists of 43 words containing pressure consonants. It is a useful assessment tool when velopharyngeal inadequacy is suspected as these pressure consonants require the build-up of intra oral pressure and, therefore adequate velopharyngeal function.

DETERMINING INTELLIGIBILITY:

                                  Calculating overall intelligibility is necessary when considering the need for treatment, identifying factors that contribute to poor intelligibility, selecting treatment goals, recording baseline information and monitoring the effect of treatment over time.

                                   As the assessment of client’s speech and language sample progress an equal importance should be given for realizing the factors that can negatively influence intelligibility.

They include:

        The number of sound errors:

                A major factor influencing speech sound intelligibility is the number and nature of speech sound errors a speaker makes. The larger the number of speaker’s production which differs from the adult standard, the more the intelligibility is reduced.

        The type of sound errors:

        Inconsistency of errors:

                Intelligibility is also affected by consistency of misarticulated sounds and the frequency with which an error sound occurs in the language. The more consistently the target sound is produced in the error and the more frequently the target sound occurs in the language, the more likely the listener will perceive the speaker’s speech as defective.

        Vowel errors:

        The rate of speech:

        Atypical prosodic characteristic of speech such as abnormal intonation or stress:

        The length and linguistic complexity of the words and utterances used:

        Insufficient vocal intensity:

        Dysfluencies, particularly severe dysfluencies that disrupts the context:

        The lack of gestures or other paralinguistic cues that assist understanding:

        The testing environment:

        The client’s anxiety about the testing situation:

        The client’s lack of familiarity with stimulus materials:

        The client’s level of fatigue:

        The clinician’s ability to understand less intelligible speech:

        The clinician’s familiarity with the client and the client’s speaking context.

     Intelligibility rating scale:

There are three rating scales for intelligibility of speech, 7 point rating scale, 3 point rating scale and 5 point rating scale.

     7 point rating scale (Fudala, 1970) :

     The 7 point rating scale consists of the following

        Speech not intelligible

        Speech usually not intelligible

        Speech difficult to understand

        Speech intelligible with careful listening

        Speech intelligible although noticeable in error

        Speech intelligible with occasional error

         Speech totally intelligible

     3 point rating scale (Bleile, 1995):

            The 3 point rating scale is assessed by administering the following

        Readily intelligible

        Intelligible if topic is known

        Unintelligible even with careful listening

     5 point rating scale:

        Completely intelligible

        Mostly intelligible

        Somewhat intelligible

        Mostly unintelligible

        Completely unintelligible

Resonance:

                 A clear observation of Velopharyngeal region during movement should be done. Symmetry during palatal movement should be checked. Amount of air which escapes during speech should be noted. Observation have o be done to see whether the palate is hanging low in the mouth. Symmetry of the palatal arches should be checked.

          There are mainly three resonance problems which should be detected through careful listening they are:

1.     Hyper nasality

2.     Hypo nasality

3.     Assimilation nasality

1.     Hyper nasality:

Occlude client’s nares and instruct him/her to recite non nasal words and phrases. If excessive nasal pressure is felt or if nasopharngeal snorting is heard, suspect hyper nasality.

Methods for identifying hyper nasality without occluding the nares also exist. Carefully listen for the nasality or hold a mirror under the nostrils and look for clouding s air moves through the nose.

2.     Hypo nasality:

Instruct the client to recite phrases with nasal sounds. Then occlude the patient’s nares and repeat the task. If the client’s unoccluded and occluded productions sound the same hypo nasality (denasality) is present.

          To differentiate between hyper and hypo nasality, instruct the patient to rapidly repeat the phrase.

 For example: maybe baby maybe baby…..

If both the words sounds like maybe hyper nasality is present. If both words sound like baby then hypo nasality is present.

3.     Assimilation nasality:

Assimilation nasality occurs when a sound that precede or    follow a

          nasal consonant are also nasalized. To evaluate, instruct the client to

          recite the words and phrases with single nasal sounds and multiple

          nasal sounds. Pay particular attention to client’s speech rate in relation

          to severity of his/her resonance problem.

PERCEPTUAL ANALYSIS OF SUPRA SEGMENTAL ASPECTS:

          The supra segmentals include:

        Stress

        Rhythm

        Intonation

        Stress:

Definition:

Jones (1956) defines stress as the degree of force with which the sound or a syllable is uttered.

        In other way stress can be defined from the listener’s point of view and speaker’s point of view. From the listener’s point of view stress can be defined as perceived loudness of a syllable/word. From the speaker’s point of view it can be defined in terms of greater muscular effort and comparatively greater force.

o   Types of stress:

In traditional phonetics, stress has been frequently divided in to

dynamic or expiratory stress and musical or melodic stress.

           Jones (1950, 1972) listed four types of stress they are Level stress, Crescendo stress, Diminuendo stress and Crescendo-Diminuendo stress. All these four types of stress have been claimed to exist in Serbo Croatian language.

  Phonemic stress or word level stress: This kind of stress

presupposes that the domain of stress is a word.

  Morphological stress: The position of stress is fixed with regard to

a given morpheme.

  Sentence level stress: When stress functions at a sentence level, it

does not change the meaning of any lexical item but it increase the relative prominence of one of the lexical item. There are three types of sentence level stress.

1.     Primary stress (non-emphatic): Each sentence automatically

has a primary stress. Here, in a sentence the important syllable or word is stressed.

2.     Contrastive stress: This occurs in a sequence of sentences

with parallel constituents that are filled with different phonemes.

3.     Emphatic stress: This is used to distinguish a sentence from

its negation.

Measurement of stress:

Perceptual:  Perceptually one can do four kinds of stress analysis.

        Stress is used in a place of an unstressed syllable/word,

        Unstressed for a stressed syllable/word,

        Equal stress on all syllables, and

        No stress on any syllable.

Acoustic: Acoustically Fo, amplitude, phoneme duration, 2^nd formant frequency of a stressed phoneme can be measured and compared with the counterpart unstressed phoneme.

Analyzing stress production:  A simple way to analyze stress is to record spontaneous speech sample. By listening to the speech sample, one can analyze for +/- ,-/+, no stress or equal stress on all syllables.

              A second way is to use prerecorded material. The subject can be audio presented with the phrases/sentences and asked to repeat. The repeated sample can be analyzed in comparison with the original. An acoustic analysis is also possible, as reference is available.

Analyzing stress perception:  AB design can used where A is a phrase with a stressed word and B is a phrase with an unstressed word. Subjects have to say whether A and B are same or different. ABA design can be used where subject has to say which is the odd phrase. Synthetic materials can be used where the individual parameters like Fo, intensity or duration can be altered. The original and the synthetic phrase can be paired and given for a discrimination task.     

The analysis of stress can be made by the analyzing

 Increase in pitch

 More force

 Increase in loudness

 Sound quality occurring in syllables

 Increase in duration

 Pause before and after stress

  (It maybe strong or weak stress)

Research and methodological issues: The parameters acknowledged as co-signals to stress also apparently share in signaling another speech attribute namely intonation, a further problem in investigating stress is that there are several types of stress these are the reason for the paucity of the studies in the area of stress. However the analysis of stress is very important as it is deviant in hearing impaired, aphasic, dysarthric, learning disabled, mentally retarded and brain damaged.    

        Rhythm:

                     There are two prosodic features which describe the temporal

characteristics of a spoken utterance, tempo and rhythm. Tempo is the rate at which utterance is spoken and rhythm of an utterance is the pattern of time intervals which elapse between the occurrences of stressed syllables.

                          The term rhythm is derived from the Greek word “Rhuthmos”  where “rhu” means flow. It’s a pattern of movement which occurs more or less temporal regularity. “It is a swing or a balance bodily movement, music or verb or phrase (Encyclopedia Britanica, 1965)”.

                          The sense of rhythm is not properly developed or disrupted in the hearing impaired, stuttering, cluttering, dysarthria, aphasia and verbal apraxia (Starkweather, 1987). 

Tests of rhythm:

T-TRIP [Tennessee test of Rhythm and Intonation pattern ( Koike & ASP, 1981)]

          It is a three part supra segmental test with 25 items. It is spoken and recorded with different rhythm and intonation pattern. The test item consists of the nonsense syllable /ma/ spoken and recorded with different rhythm and intonation patterns. Items 1 to 17 are for testing rhythm. In part 1 the rhythm section had items 1-14 had 2-6 syllables that varied in stress and tempo. In part 2, item 15, 16 and 17 had a faster tempo with 3 syllables per beat and produced 3-9 syllables.

Limitations:

        Inability to achieve an adequate control over frequency.

        Perception of rhythm only. Intensity and durational cues are utilized and not F0.

        Difficult to test.

Synthetic test of rhythm [Jayanthi Ray, 1993]

           This test had 17 synthetic stimuli varying in Fo, intensity and duration. There are three parts in the test. In part 1, 6 stimuli with change in Fo (increasing in steps of 10Hz steps) were prepared. Intensity and duration were kept constant. In part 2, 6 stimuli with change in intensity (increase in 10dB steps) were prepared. Fo  and duration were kept constant. In part 3, five stimuli with change in duration (increase in 10 ms steps) and constant Fo and intensity were generated. These stimuli were given for imitation in 20 kannada speaking adults and 40 children.

This test could be used

        As a clinical diagnostic tools in order to explore the suprasegmental functioning in patients having dysprosodia.

        As a therapeutic tool for facilitating rhythmic speech and hence enhancing speech intelligibility in those, who have arhythmia.

Measurement of rhythm:

Speech production:

               One can record speech sample and tap for rhythm and indicate the taps on a transcribed material. The speech samples of normals can be compared with that of the clinical population for production of rhythm.

               Acoustically one can measure Fo, intensity and duration of the tapped syllable. These acoustic measures in clinical population can be compared to that of normals.

        Intonation:

                               Intonation is an important feature of prosody. Intonation is defined as the fundamental frequency (pitch) variations in phrase/clauses/sentences in a temporal dimensions.

                              Intonation is the movement of pitch in an utterance. It is different from other utterances in that it is meaningful. A rising pitch indicates a question and a falling a statements.    

                                It is the variation of speech pitch as a function of time (Collier, 1991). Intonation plays an important role in intelligibility and naturalness of synthetic speech (Olive et al, 1974).

Tests of intonation:

T-TRIP [Tennessee test for rhythm and intonation patterns ( Koike and Asp, 1971)]

            It is a 25-items test with 18-25 items for intonation. Nonsense syllable as spoken in various intonation patterns by an adult male trained in phonetics is used. The following figure shows various intonation patterns used in T-TRIP.

              

                

  

                   

1+Low, 2= Mild, 3=High pitch

As this test is based on spoken /ma/  Fo control might not be very good.

According to Hiret (1977) 2 binary features are high and low.

Low- lowering of pitch

High- slightly rise in pitch

Droptone-combination of high and low

ADVANTAGES OF PERCEPTUAL ANALYSIS:

        Evaluation is non invasive.

        Instruments are not required.

DISADVANTAGES OF PERCEPTUAL ANALYSIS:

        There are no particular values obtained from these tests.

        A complete diagnosis cannot be done only with perceptual analysis.

        The perceptual analysis are unreliable for the

      judgment among clinician.

        It is difficult to quantify and cannot directly test hypothesis about patho-sphysiology underlying perceived speech abnormalities

IMPORTANCE OF PERCEPTUAL ANALYSIS IN CLINICAL     SET-UP FOR DIAGNOSIS:-

                              The evaluation of speech disorder always begins with a perceptual judgment that speech has changed or is abnormal or different in someway. Perceptual evaluations are mainly done based on the auditory-perceptual attributes of speech. Perceptual evaluations are the “Gold- Standard” for clinical differential diagnosis, judgment of severity, many decisions about management and the assessment of functional change.

            Perceptual evaluation is the important primary step in assessment of a case. It gives the clinician a brief idea about the case and about the management procedure which is to be carried out.

            Perceptual evaluation tests are less time consuming so it can be used as screening tool for different motor speech disorder. Since the perceptual evaluation gives a brief idea about the problem of the client it helps the clinician in selecting various diagnostic tests for detailed assessment of that particular problem. This indirectly helps in reducing the time for the assessment of the disorder.

            In most cases the ear is the best instrument for evaluating deficits of the motor speech mechanism. A clinician with an experienced ear can often make a quick, accurate diagnosis based only on the acoustic characteristic of patient’s speech. The importance of developing a sharp ear for the assessment of motor speech disorder cannot be overstated.

 REFERENCES:

        SPEECH CORRECTION: CHARLES VAN RIPER

        ARTICULATION AND PHONOLOGICAL DISORDER 3^rd EDITION                          : BERNTHAL, JOHN.E. & BANKSON,

                                                    NICHOLAS. W.

        MOTOR SPEECH DISORDERS

                                                 : JOSEPH DUFFY.

        ASSESSMENT IN SPEECH LANGUAGE PATHOLOGY

                                                 : SHIPLEY

            *******************BEST OF LUCK******************