New Study Shows Oticon Speech Guard Helps Deliver Sound Information Children Need for High Speech Recognition

19 July 2016
A new study shows the adaptive-compression scheme found in Oticon Speech Guard provides a beneficial alternative to traditional fast wide dynamic range compression. The study of children, ages 8 - 12 years with moderately-severe sensorineural hearing loss, found that Speech Guard’s floating linear gain compression helps to deliver the essential sound information needed to improve speech recognition in children with hearing loss. Children participating in the study showed clear and significant advantages of 6-8% in speech recognition in both steady state and modulated noise. The magnitude of the speech recognition results was maintained when the children were performing a secondary task in addition to the primary auditory task. The results indicate that even when cognitively loaded, the compression characteristics of Speech Guard are still beneficial to the child.

In acoustic analysis, the intensity contrasts in a speech signal are better preserved with Speech Guard processing than with traditional single compression and likely account for the children’s increased speech recognition.

“This is the first research study to investigate the benefits of Speech Guard over traditional syllabic WDRC,” says Kamilla Angelo, Senior Researcher, Ph.D., Clinical Evidence, Oticon Paediatrics. “The results support our hypothesis that preserving the dynamic of speech gives children a more natural, detailed and undistorted sound picture and thus better speech recognition. The data gives us confidence that with Speech Guard we are providing the children with our best possible amplitude compression scheme. Speech Guard compression has been in our Super Power Safari devices for two years and is now in the Pro model of our new Paediatric hearing instrument family, Oticon Sensei.

Insights on Amplitude Compression Strategies in Paediatric Hearing Aids
While fast wide dynamic range compression (WDRC) effectively increases low-level speech sounds, it also holds the risk to disrupt or alter binaural cues that are important to a child’s ability to learn to spatially separate sound sources. The American Academy of Audiology has recommended amplitude compression strategies that, similar to Speech Guard, “ensure a range of input levels is compressed sufficiently” and “accommodate sensitivity to loud sounds while restoring low level speech audibility” and that, at the same time, “minimize alternation of speech cues.” The new study results support Oticon’s position on the use of Speech Guard in hearing solutions specifically designed for paediatric patients.

Study Methodology
The study, commissioned by Oticon A/S, involved children, ages 8 - 12 years with moderately-severe sensorineural hearing loss. The study participants were fitted binaurally with both Acto Pro and Agil Pro instruments with all advanced features disabled. This ensured that the amplitude compression scheme was the only difference. Acto Pro instruments featured the WDRC amplification scheme. The Agil Pro instruments featured Speech Guard’s adaptive-compression that responds slowly and operates in a linear manner when the acoustic environment is stable and adjusts swiftly to prevent sounds from becoming uncomfortable when the acoustic environment changes abruptly. Sentence material from the Hearing in Noise Test for Children (Hint-C) was used to score speech recognition.

Every Child Benefits
In testing, the children’s receptive vocabulary was measured using the Peabody Picture Vocabulary Test (PPVTv4). Results indicated that irrespective of their vocabulary performance, each child on average benefited from the Speech Guard compression scheme. In further acoustic analysis, Oticon Lead Developer Michael S. Pedersen, Ph.D. showed that the modulation of the speech signal is better maintained with Speech Guard than with fast WDRC.

“Evidence such as that from the study provides further validation that the adaptive amplification strategy provided by Speech Guard can help to optimize auditory development,” says Heine Højvang Andersen, Senior Director of Sales & Marketing, Paediatrics. “Oticon is committed to providing a better future for every child with hearing loss. Our goal is to continue to deliver innovative solutions with features that culminate in great speech understanding for children in the many complex environments they encounter every day.”

The next generation Speech Guard, Speech Guard E, is featured in Oticon Sensei, Oticon’s new family of premium paediatric hearing instruments. Sensei’s combination of audiological features is designed to optimize auditory and cognitive habilitation so that children can develop their auditory systems as fully and naturally as possible.

Learn more about Speech Guard E and Oticon Sensei.

The linear window of Speech Guard E is indicated by the purple line within the input/output domain. The window will move depending on the input level. At all times it will thus stay within the auditory dynamic range, making the output audible, comfortable and clear.