PP311 - Extended High-Frequency Hearing and Its Effect on Speech Perception in Noise

Abstract:
Hearing is vital for spoken communication and social interaction. While traditional audiometry measures through 8 kHz, extended high-frequency (EHF) hearing (above 8 kHz) is crucial for understanding speech in noise. This study investigates the link between EHF hearing and speech perception in noisy environments, particularly focusing on age-related changes and differences among English monolinguals and Spanish-English bilinguals. By using pure tone audiometry, Quick Speech-in-Noise (QuickSIN), and Audible Contrast Threshold (ACT), this research aims to understand how variations in EHF hearing affect speech recognition, potentially improving diagnostic and intervention strategies for hearing impairments.

Summary:
Background
The standard range for audiometric testing, 250 Hz to 8 kHz, captures the essential frequencies for human hearing, but the full spectrum extends from 20 Hz to 20 kHz, including extended high frequencies (EHF) above 8 kHz. EHF, often considered less significant, is now recognized for its crucial role in speech perception, particularly in noisy environments, and can be an early indicator of auditory decline, preceding detectable hearing loss. Consequently, EHF testing is valuable for early detection, hearing aid design, and rehabilitative strategies targeting improved speech perception in challenging listening conditions.

Speech-in-noise difficulties are common among individuals with hearing loss, and even those with normal thresholds. Quick Speech-in-Noise (QuickSIN) is widely used in clinical settings to evaluate speech recognition in noisy environments, but it focuses on frequencies up to 4 kHz, excluding the EHF range, which limits its efficacy for those with high-frequency hearing loss. Combining QuickSIN with language-independent tools like the Audible Contrast Threshold (ACT), which measures speech-in-noise ability across language backgrounds, could provide a more comprehensive understanding of speech perception and lead to better-tailored auditory interventions.

Recent findings by Hovsepyan et al. (2024) indicate that higher acoustic reflex thresholds correlate with poorer EHF and speech-in-noise performance, suggesting that standard audiograms may overlook these losses. Additionally, research on bilingualism reveals unique challenges for bilingual individuals in speech perception within noisy environments, potentially due to the added cognitive demands of processing multiple languages.

Aim
This study examines the relationships among EHF hearing, speech-in-noise performance, and bilingualism by comparing monolingual English speakers with Spanish-English bilinguals. Using EHF audiometry, QuickSIN, and ACT, it investigates how EHF loss affects speech perception, especially for those with normal hearing on standard tests.

Methods
Participants were divided by language background (monolingual English and Spanish-English bilinguals) and age (younger and older adults). All completed EHF audiometry, QuickSIN, and ACT tests to assess speech perception in noise. The study analyzed whether EHF sensitivity differs by age and language background and how these differences impact speech understanding in noisy environments.

Results
Preliminary findings show that younger adults generally have better EHF thresholds and perform better on QuickSIN and ACT tests than older adults. Bilingual participants perform slightly lower on QuickSIN compared to monolinguals, possibly due to cognitive demands associated with processing multiple languages. EHF loss is associated with poorer speech-in-noise performance, indicating that EHF testing can detect hearing difficulties overlooked by standard audiometry.

Conclusion
This study highlights the importance of EHF in speech perception in noise. The combined use of EHF audiometry, QuickSIN, and ACT provides deeper insights into the impact of high-frequency loss on communication, even for those with normal hearing thresholds. These findings support including EHF in audiological evaluations, with potential applications in early diagnosis, hearing aid customization, and auditory training to improve speech comprehension in complex settings.