Does speech therapy change voice quality in children with CP?

Speech therapy focusing on aspects such as breath control and speech tempo has shown to improve voice quality and articulation. These changes can boost intelligibility, i.e. how well speakers are understood by listeners. Nick Miller and colleagues therefore expected that work on breathing should help improve intelligibility. Whether this is indeed the case was tested in a study published in 2013. Specifically, the authors explored whether perceived voice quality is altered following a speech therapy focusing on respiration and phonation.

 

The study used single word and connected speech data of 16 children with CP (mean age was 14) collected before and after a six-week block of speech therapy. 16 SLTs took part in the perception study. They were asked to rate the voice quality of the speech files using the GRBAS scale. This is an evaluation scale that perceptually rates the voice quality for 5 parameters:  

     

 - Grade (degree of voice abnormality)
 - Roughness (steadiness of vocal cord function)

 -  Breathiness (extend of air leakage)

 -  Asthenia (weakness)

 -  Strain (tension)

Each parameter is assigned a value on a 4-point scale, where 0 is normal and 3 is severe. The SLTs were specialists in voice problems and knew how to use the scale. They rated the speech files assigned to them without knowing whether it was a recording made before or after therapy.

Findings showed that the children with CP had voice problems - before and after therapy. They also showed that the perceived changes in voice quality were small, which means that the children’s voice did not change much as a result of the therapy. This in turn means that voice changes were not the reason for the improvements seen for intelligibility. And indeed, only asthenia, i.e. weakness of the voice, was found to have some importance for intelligibility. Overall, other aspects such as tempo and speech melody will need exploring to explain the improvements in intelligibility observed after therapy.

Miller, N., Pennington, L., Robson, S., Roelant, E., Steen, N., Lombardo, E. (2013). Changes in Voice Quality after Speech-Language Therapy Intervention in Older Children with Cerebral Palsy, Folia Phoniatrica et Logopaedica, 65(4), 200-207.

Production of consonants in school-aged children with CP

Detailed descriptions of speech features in children with CP are a prerequisite for providing suitable interventions for children with speech impairments. However, as Ann Nordberg and colleagues point out in their most recent article: thorough descriptions of speech impairment in children with CP are rare - and even non-existent for those with ataxic dysarthria. The aim of their study was therefore to investigate the production of consonants produced by 19 school-aged Swedish-speaking children with CP in order to fill some of the blank spaces.

The children participating in the study were about 11 years old, and - according to medical records -had some form of speech impairment. In addition, 9 of the 19 children were known to have cognitive problems. The children were asked to name 59 pictures of the Swedish Articulation and Nasality Test (SVANTE), which covers the whole range of Swedish oral consonants prone to articulation deficits. Two speech and language therapists then phonetically analysed the consonants to obtain the percentage of correctly articulated consonants, and describe the error patterns. They also rated the severity of the speech impairment, whether the children sounded nasal and whether anything about their breathing, voice quality and prosody was noticeable.

Results showed that more than 50% of the children had severe difficulties with articulation resulting in a mean score of correct consonants that was well below that of typically developing children. The authors also found that children with spastic and dyskinetic dysarthria did better than the kids with ataxic dysarthria. Voicing errors were the most frequent type of errors followed by substitutions and omissions, which might be a result of poorly controlled phonation.

The authors further found that most of the children had mild dysarthria, and nasality – as opposed to previous reports – was not a common feature of the children’s speech. However, 13 children had problems related to breathing including having low energy, being breathless and not having enough air for speech production. The same number of children was also found to have unusual voice features such as high pitch levels, harsh voice and creaky voice. A further 6 of the 19 children were described as having deviant prosodic speech characteristics such as monotonous speech. The authors conclude that these features are equally important for the perception of dysarthria as the articulation deficit, and listeners may rely on the whole range of speech changes when making judgements about the presence and severity of dysarthria.


Nordberg, A., Miniscalco, C. & Lohmander, A. (2014). Consonant production and overall speech characteristics in school-aged children with cerebral palsy and speech impairment. International Journal of Speech-Language Pathology, 16(4), 386-395.

treatment effectiveness

Although a number of articles describing treatment approaches for developmental dysarthria were published over the years, to date only few studies were conducted to test whether dysarthria intervention in children with CP is actually effective.

A series of therapy studies conducted by Lindsay Pennington’s research group in Newcastle addressed this research gap. Pennington, Smallman and Farrier (2006) started off with a small scale intervention study in which six children with CP received individual dysarthria therapy targeting breath support and volume across utterances. Improvement was measured by means of intelligibility of single words and connected speech. Four of the six children were more intelligible directly after therapy, although improvement was only maintained in one speaker seven weeks later.

This study was followed by a more extensive investigation in 2010. Pennington and colleagues wanted to find out whether a systems approach targeting breath support, phonation and speech rate can increase the speech intelligibility of older children with CP. Sixteen children with moderate to severe dysarthria aged 12 to 18 years attended three therapy sessions per week over a period of six weeks. As in the previous study, improvement was measured in terms of intelligibility in single words and connected speech across four time points (6 and 1 week pre-therapy, and 1 and 6 weeks post-therapy). The intervention was found to increase speech intelligibility for familiar and unfamiliar listeners for both measures. Importantly, changes were maintained after 6 weeks, indicating acquisition of stable motor patterns.

A recent study by the same lead author examined intensive dysarthria therapy for younger children with CP. Just as the previous study, the intervention targeted breath support, phonation and speech rate. Fifteen children were recruited aged 5 to 11 years. The therapy success was measured in terms of intelligibility and participation in conversational interactions across five points: 6 and 1 week pre-therapy and 1, 6 and 12 weeks post-therapy. Overall, gains in intelligibility and participation in interaction were observed, although scores in the latter did not correlate with changes in the former. This finding shows that some children interacted more following therapy - perhaps due to increased confidence - irrespective of how much their speech intelligibility improved.

Pennington, L., Smallman, C., & Farrier, F. (2006). Intensive dysarthria therapy for older children with cerebral palsy: Findings from six cases. Child Language Teaching & Therapy, 22, 255–273.

Pennington, L., Miller, N., Robson, S. & Steen, N. (2010). Intensive speech and language therapy for older children with cerebral palsy: a systems approach. Developmental Medicine & Child Neurology, 52, 337–344.

Pennington, L., Roelant, E., Thompson, V., Robson, S., Steen, N. & Miller, N. (2013). Intensive dysarthria therapy for younger children with cerebral palsy. Developmental Medicine & Child Neurology, 55, 464–71.