Speech Perception in Bilateral Hearing Aid Users With Different Grades of Asymmetric Hearing Loss

Impact of unilateral vs. bilateral evaluation on cochlear implant candidacy

BACKGROUND

The indication criteria for cochlear implantation differ considerably across regions.

OBJECTIVES

To estimate the effects of different candidacy criteria on the number of cochlear implant (CI) candidates.

METHODS

We analysed a very large clinical audiological database comprising pure-tone thresholds and speech-audiometric data in order to identify CI candidates on the basis of different audiometric candidacy criteria. In particular, we simulated the effects of three different CI candidacy criteria.

RESULTS

The bilateral evaluation of CI candidacy has the strongest influence on the number of potential CI candidates. Additionally, the cut-off criteria for middle-ear implants have a large effect on numbers of candidates when air conduction has deteriorated.Conclusions and Significance: Expanding the indication criteria opens up the possibility of improving the accurate identification of individual cases suitable for cochlear-implant provision.

Effect of a processing delay between direct and delayed sound in simulated open fit hearing aids on speech intelligibility in noise

Introduction

Subjects with mild to moderate hearing loss today often receive hearing aids (HA) with open-fitting (OF). In OF, direct sound reaches the eardrums with minimal damping. Due to the required processing delay in digital HA, the amplified HA sound follows some milliseconds later. This process occurs in both ears symmetrically in bilateral HA provision and is likely to have no or minor detrimental effect on binaural hearing. However, the delayed and amplified sound are only present in one ear in cases of unilateral hearing loss provided with one HA. This processing alters interaural timing differences in the resulting ear signals.

Methods

In the present study, an experiment with normal-hearing subjects to investigate speech intelligibility in noise with direct and delayed sound was performed to mimic unilateral and bilateral HA provision with OF.

Results

The outcomes reveal that these delays affect speech reception thresholds (SRT) in the unilateral OF simulation when presenting speech and noise from different spatial directions. A significant decrease in the median SRT from -18.1 to -14.7 dB SNR is observed when typical HA processing delays are applied. On the other hand, SRT was independent of the delay between direct and delayed sound in the bilateral OF simulation.

Discussion

The significant effect emphasizes the development of rapid processing algorithms for unilateral HA provision.

Outcomes from 7 years of a direct to audiology referral pathway

Background

The direct to audiology via ENT referral pathway was designed to enhance patient access to audiology services. The pathway is recommended in the Otolaryngology Head & Neck Surgery: a model of care for Ireland report, published in 2019.

Aims

This study aimed to review the outcomes of all patients that attended our institution over the last seven years.

Methods

A retrospective review of the direct to audiology referral service from March 2014 to December 2021 was conducted. Outcomes were defined by the pathway each patient took following attendance at the audiology clinic. Patients were either (i) discharged, (ii) referred for hearing aid(s) or (iii) identified as candidates for further diagnostic assessments, including a follow-up at the ENT outpatient clinic.

Results

During the time frame, 419 patients were triaged to the pathway. The average wait time was 13 days. The average age was 53 years (range 16–96 years, SD = 6.1). Approximately 34% (n = 143) of all patients referred were discharged back to the GP by the audiologist, but 66% (n = 276) presented with ‘red flags’ and needed further investigation in the ENT clinic, with 30% (n = 73) ultimately requiring imaging studies. Over half (n = 254, 61%) were referred for hearing aids.

Conclusion

The direct to audiology initiative has proven effective at reducing waiting times for ENT patients solely in need of audiological intervention. Approximately one-third of these referrals to the ENT service can be assessed comprehensively in the audiology clinic, thereby reducing the demand for ENT clinics, enhancing service provision and expediting onwards referral for amplification.