A comparison of automated verification using paediatric hearing aids.

OBJECTIVE: Best-practice guidelines recommend the use of hearing aid verification in children; however, this is not always performed. Automated hearing aid verification has been reported to be more accurate and efficient than manual verification in adults, but it is not known if this transfers to the paediatric population. DESIGN: A within-group design compared manual and automated hearing aid verification on four measures; fitting accuracy, prescription targets, completion time, and the speech intelligibility index. SAMPLE: Twenty paediatric patient hearing aid profiles (M = 8.25 years) with unilateral or bilateral hearing aids. RESULTS: A Wilcoxon-signed rank test indicated manual verification achieved a significantly closer match to target at 0.5 kHz, by an average of 1 dB. There were no significant differences at any other frequency. Across 80 comparisons (four frequencies measured in 20 listeners), 82.5% of automated verifications were identical to, or within 1 dB of, manual verifications. A paired-samples t-test confirmed automated verification to be an average of 91.9 seconds faster than manual verification. CONCLUSION: Automated verification was able to provide an accurate match to target within recommended tolerances for hearing aid fittings and was significantly quicker than manual verification. These data suggest that automated verification of hearing aids could play a role in paediatric audiological management.

Measuring access to high-modulation-rate envelope speech cues in clinically fitted auditory prostheses.

The signal processing used to increase intelligibility within the hearing-impaired listener introduces distortions in the modulation patterns of a signal. Trade-offs have to be made between improved audibility and the loss of fidelity. Acoustic hearing impairment can cause reduced access to temporal fine structure (TFS), while cochlear implant processing, used to treat profound hearing impairment, has reduced ability to convey TFS, hence forcing greater reliance on modulation cues. Target speech mixed with a competing talker was split into 8-22 frequency channels. From each channel, separate low-rate (EmodL, <16 Hz) and high-rate (EmodH, <300 Hz) versions of the envelope modulation were extracted, which resulted in low or high intelligibility, respectively. The EModL modulations were preserved in channel valleys and cross-faded to EModH in channel peaks. The cross-faded signal modulated a tone carrier in each channel. The modulated carriers were summed across channels and presented to hearing aid (HA) and cochlear implant users. Their ability to access high-rate modulation cues and the dynamic range of this access was assessed. Clinically fitted hearing aids resulted in 10% lower intelligibility than simulated high-quality aids. Encouragingly, cochlear implantees were able to extract high-rate information over a dynamic range similar to that for the HA users.

The near non-existence of "pure" energetic masking release for speech: Extension to spectro-temporal modulation and glimpsing.

Stone and Moore [(2014). J. Acoust. Soc Am. 135, 1967-77], showed that the introduction of explicit temporal-only modulations to a speech masker, that otherwise produced a near-constant envelope at the output of each auditory filter, rarely resulted in improved intelligibility, except at a very low modulation rate. This represents a failure in "dip-listening" or "glimpsing" [Cooke (2006). J. Acoust. Soc. Am. 119, 1562-1573], a facility where listeners are presumed to benefit from the temporarily improved signal-to-noise ratio during the masker dips. The dips of Stone and Moore only varied temporally, so Stone and Moore's method was used here to investigate the effect of maskers with both spectral and temporal dips, a pattern more representative of real-world maskers. For sinusoidally shaped modulations, intelligibility improved only at very low modulation rates, below 2 Hz temporally and 0.14 ripples/auditory filter spectrally. Square-wave modulation at a rate of 4 Hz resulted in improved intelligibility when only one cycle of spectral modulation was present across the audio bandwidth. Compared to the spectro-temporal extent of dips present during real-world noisy speech, dips generated by the reported modulation patterns were very large, further supporting the notion that dip-listening reflects a release from modulation masking and not energetic masking.