Speech perception in various acoustic environments: Comparison of different sound coding strategies

Objectives to compare speech perception in a quiet and noisy environment using a basic audio coding strategy (CIS) and a modern strategy (ACE) over a period of 24 months. Material and methods. The study involved 30 patients who received hearing rehabilitation in the National Medical Research Center for Otorhinolaryngology of the Federal Medico-Biological Agency in the period of 2018 2021. The inclusion criteria were: implantation in the adult age (from 18 to 45 years), speaking fluent Russian, hearing loss after speech skills formation. After initialization and programming of the speech processor, the patients underwent speech audiometry in a free sound field using syllabic and speech tables in silence and noise. The results were collected in the special MS Excel templates and subjected to statistical analysis. Results. The intelligibility of syllables in patients with CIS and ACE strategies took comparable values and grew with experience within 24 months (from 52 7.00% at the beginning of the study to 72 7.25% at the end), the greatest increase in intelligibility was noted in the first 3 months after connecting the speech processor (from 52 7.00% to 66 7.87%). Using the Greenberg speech table in silence, the groups with the CIS strategy and the ACE strategy obtained similar results with a slight advantage of the ACE strategy up to 6 months of the study. Later, a significantly higher increase in speech perception was observed in the group with the ACE strategy compared to the group with CIS. After 12 months, the perception tests showed 67 8.62% in patients with CIS strategy and 71 7.54% in patients with ACE, after 24 months the results were 68 9.12%, and 72 8.62% respectively. Under noise conditions, we observed an increase of the difference between groups starting from 6 months (41 5.33% in patients with CIS versus 43.3 7.55% with ACE), the largest difference was registered after 24 months (51 5.50% versus 57 8.25% respectively). Conclusion. When compared to the basic strategy, a modern sound coding strategy with a higher resolution can improve speech perception especially with complex speech patterns and in a noisy environment.