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.