Background:
The aim was to measure, evaluate, and improve voice pitch characteristics (measured on the basis of the average fundamental frequency, Fx), in students aged 10–12 who had substantial or severe hearing loss and were fitted with hearing aids. Two core questions were asked: (i) Is therapy using the PCLX Laryngograph Processor effective? (ii) Which factors affect the outcome of therapy?

Material and Methods:
Therapy based on a multimedia computer workstation using the PCLX Laryngograph Processor is proposed, a system capable of visualizing voiced speech using electroglotography. The study is constructed as a pedagogical experiment, using parallel groups and Mill’s method of difference.

Results:
Pretest results show that, prior to therapy sessions, both groups (experimental and control) were largely equivalent with respect to voice pitch characteristics. In total, 49 students exhibited anomalous voice pitch characteristics while 14 cases could be described as unstable (with pitch sometimes correct, but not consistently so). Correlations between concomitant variables and the effectiveness of the therapeutic process were found. In particular, intelligence and visual-motor coordination played a significant role. Variables such as learning speed, working memory capacity, forgetfulness, time since onset of hearing loss, and degree of aural impairment seem to be less important. Improvements appeared to depend on the subject’s family environment and were largely independent of age and degree of hearing loss.

Conclusions:
The research has shown that in most aurally impaired subjects voice pitch is too high and needs to be corrected. The proposed therapy is shown to be highly effective, producing persistent long-term improvements, especially in the case of younger students.