Exploring Hearing Care Technology from Clinic to Capability.

Healthcare systems are traditionally a clinician-led and reactive structure that does not promote clients managing their health issues or concerns from an early stage. However, when clients are proactive in starting their healthcare earlier than later, they can achieve better outcomes and quality of life. Hearing healthcare and the rehabilitation journey currently fit into this reactive and traditional model of care. With the development of service delivery models evolving to offer services to the consumer online and where they are predominately getting their healthcare information from the internet and the advancement of digital applications and hearing devices beyond traditional hearing aid structures, we are seeing a change in how consumers engage in hearing care. Similarly, as the range of hearing devices evolves with increasingly blended and standard levels of technology across consumer earbuds/headphones and medical grade hearing aids, we are seeing a convergence of consumers engaging earlier and becoming increasingly aware of hearing health needs. This article will discuss how the channels, service, and technology are coming together to reform traditionally clinician-led healthcare models to an earlier consumer-led model and the benefits and limitations associated with it. Additionally, we look to explore advances in hearing technologies and services, and if these will or can contribute to a behavioral change in the hearing healthcare journey of consumers.

Use of a Deep Recurrent Neural Network to Reduce Wind Noise: Effects on Judged Speech Intelligibility and Sound Quality.

Despite great advances in hearing-aid technology, users still experience problems with noise in windy environments. The potential benefits of using a deep recurrent neural network (RNN) for reducing wind noise were assessed. The RNN was trained using recordings of the output of the two microphones of a behind-the-ear hearing aid in response to male and female speech at various azimuths in the presence of noise produced by wind from various azimuths with a velocity of 3 m/s, using the "clean" speech as a reference. A paired-comparison procedure was used to compare all possible combinations of three conditions for subjective intelligibility and for sound quality or comfort. The conditions were unprocessed noisy speech, noisy speech processed using the RNN, and noisy speech that was high-pass filtered (which also reduced wind noise). Eighteen native English-speaking participants were tested, nine with normal hearing and nine with mild-to-moderate hearing impairment. Frequency-dependent linear amplification was provided for the latter. Processing using the RNN was significantly preferred over no processing by both subject groups for both subjective intelligibility and sound quality, although the magnitude of the preferences was small. High-pass filtering (HPF) was not significantly preferred over no processing. Although RNN was significantly preferred over HPF only for sound quality for the hearing-impaired participants, for the results as a whole, there was a preference for RNN over HPF. Overall, the results suggest that reduction of wind noise using an RNN is possible and might have beneficial effects when used in hearing aids.

Wind noise within and across behind-the-ear and miniature behind-the-ear hearing aids.

Previous studies investigated wind noise with Behind-The-Ear (BTE) hearing aids, but not the more common mini-BTE style of device, which typically has a smaller shell and microphones located more deeply behind the pinna. The current study investigated wind-noise levels across one BTE and two mini-BTE devices, and between the front and rear omni-directional microphones within devices. Levels were measured at two wind speeds (3 and 6 m/s) and 36 wind azimuths (10° increments). The pattern of wind-noise level versus azimuth was similar across mini-BTE devices, and differed for the BTE device. However, mean levels were markedly different across mini-BTE devices, and could be higher, lower, or similar to those of the BTE device. For within-device level differences, the pattern and mean across azimuth were similar across mini-BTE devices, and differed for the BTE device. Wind noise had the potential to slightly or severely reduce speech intelligibility at 3 or 6 m/s, respectively, across all devices.

Preferred delay and phase-frequency response of open-canal hearing aids with music at low insertion gain.

OBJECTIVE: Preferences between low delays and phase-frequency responses of behind-the-ear, open-canal hearing aids were investigated with acoustic conditions deemed sensitive to delay effects by normal-hearing listeners. DESIGN: Hearing aids with the following selectable delay and phase response options were fitted at low insertion gain: (1) 1.4 ms delay, minimum phase; (2) 3.4 ms delay, minimum phase; and (3) 3.4 ms delay, linear phase. Blind paired comparisons were made between processing options and between each option and a muted hearing-aid output with two music stimuli. The three alternative forced choice responses were "Slightly prefer", "Prefer", or "Strongly prefer". STUDY SAMPLE: Twelve hearing-impaired musicians. RESULTS: At the 3.4-ms delay, the minimum-phase response was significantly preferred to the linear-phase response for one music sample and vice-versa for the other sample with a sign test (p < 0.04) but not a Wilcoxon signed rank test that accounted for the low preference strength. Preferences between all other processing conditions were not significant. CONCLUSIONS: In acoustic conditions sensitive to delay effects, delays of 1.4 or 3.4 ms were either not detected or no less preferable than no delayed aided signal. It is unclear whether different phase-frequency responses may be preferred with different music stimuli.

Wind noise at microphones within and across hearing aids at wind speeds below and above microphone saturation.

The variation of wind noise at hearing-aid microphones with wind speed, wind azimuth, and hearing-aid style was investigated. Comparisons were made across behind-the-ear (BTE) and completely-in-canal (CIC) devices, and between microphones within BTE devices. One CIC device and two BTE devices were placed on a Knowles Electronics Manikin for Acoustic Research. The smaller BTE device had vented plastic windshields around its microphone ports while the larger BTE device had none. The microphone output signals were digitally recorded in wind generated at 0, 3, 6, and 12 m/s at 8 wind azimuths. The microphone output signals were saturated at 12 m/s with wind-noise levels of up to 116 dB SPL at the microphone output. Wind-noise levels differed by up to 12 dB between microphones within the same BTE device, and across BTE devices by up to 6 or 8 dB for front or rear microphones, respectively. On average, wind-noise levels were lowest with the CIC device and highest at the rear microphone of the smaller BTE device. Engineering and clinical implications are discussed.

Environmental noise reduction configuration: Effects on preferences, satisfaction, and speech understanding.

The effects of four configurations of an environmental noise reduction (ENR) algorithm on preferences, speech understanding, and satisfaction were investigated. The gain reduction at 0 dB modulation depth was either 10 dB in all channels (ENR StrongFlat) or shaped from 2-10 dB across channels according to a speech importance function (ENR MildSII). This gain reduction was either invariant (ENR Constant) or varied with (ENR Variable) the noise level. Ten hearing-impaired participants blindly compared pairs of configurations in real-world situations and recorded their preferences. Sentence reception thresholds (SRTs) were measured in quiet and noise, and satisfaction was rated with speech in noise. Half of the participants preferred ENR MildSII and half preferred ENR StrongFlat. All preferred ENR Variable to ENR Constant. Overall, the preferred ENR configuration was preferred to ENR off in 90% of responses. No statistically significant effect on SRTs was found, but a clinically significant effect of up to 2 dB could not be ruled out from the available data. ENR significantly improved satisfaction for listening comfort, ease of speech understanding, and sound quality.

Effects of expansion algorithms on speech reception thresholds.

Expansion is commonly used to reduce microphone noise and low-level environmental noises that can be annoying to hearing aid users. It may also improve or reduce the perception of low-level speech. This study assessed the impact of two expansion algorithms, single and multiple channel, on speech reception thresholds (SRT) with 10 hearing impaired listeners wearing hearing aids with ADRO processing. The single-channel algorithm suppressed sounds below 45 dB A, while the multiple-channel algorithm suppressed sounds below the long-term average spectrum of speech at either 55 or 45 dB SPL. The mean HINT SRTs in quiet were 39.4, 40.7, 40.6, and 41.8 dB A without expansion, with single-channel expansion, and with multiple-channel expansion at expansion thresholds of 45 and 55 dB SPL, respectively. The difference in mean SRT was only statistically significant between no expansion and multiple-channel expansion at a 55 dB SPL threshold. A regression analysis between the change in individual SRT for each expansion condition and pure tone average hearing loss showed no correlation. Our calculations indicate that only those with exceptionally good hearing will find microphone noise audible. The current practice of prescribing expansion algorithms based on hearing thresholds alone is questioned, and other rationales are discussed.

The design and evaluation of a hearing aid with trainable amplification parameters.

OBJECTIVES: A prototype hearing aid with trainable amplification parameters (compression threshold, gain below the compression threshold, compression ratio, and noise suppression strength) was evaluated to answer the following research questions: (1) In everyday listening situations, do aid users prefer amplification parameters that were a result of training the aid in such situations to a set of untrained parameters that were prescribed and customized in a clinic? (2) Does the provision of trained noise suppression significantly increase the preference for the trained settings? (3) Is the preference for the trained settings correlated with a measure of training? DESIGN: Three take-home trials were conducted. I. The training trial: Eighteen subjects with symmetric, sensorineural hearing loss were recruited. The aid was fitted with untrained settings based on the NAL-NL1 prescription, and the subjects then attempted to train the aid's amplification settings to their preference in everyday situations for a period of between 1 and 4 weeks. II. The first double-blind comparison trial: Thirteen of the training-trial subjects agreed to participate. These subjects blindly compared their trained settings to untrained settings and voted for their preferred settings in everyday situations for a period of 1 week. Noise suppression was enabled for the trained settings (with trained noise suppression strength), but not for the untrained settings. III. The second double-blind comparison trial: A repeat of the first comparison trial, but with noise suppression disabled for both the trained and untrained settings. Subjects who had high trained noise suppression strength values for the first comparison trial were recruited (eight subjects agreed to participate). This trial more clearly evaluated the effect of training the compression characteristics, and differences between the results of the comparison trials showed the effect of the trained noise suppression. RESULTS: For the first comparison trial, nine subjects voted for the trained settings significantly more often than the untrained settings in real life environments. Three subjects had nonsignificant results, and one subject had a significant preference for the untrained settings. The results of the first and second comparison trials were not significantly different for seven of the eight subjects who participated in both trials. Thus, for these subjects (and the group data) the provision of trained noise suppression did not have a significant effect on the preference for the trained settings. Data logged during the trials showed that the percentage of votes for the trained settings for the first comparison trial was most strongly correlated with the number of hours of aid use during the training trial, although this was not significant when all subjects were included. CONCLUSIONS: In everyday listening situations, aid users can train this prototype aid to provide amplification parameters that, in such situations, they prefer significantly more often than untrained parameters prescribed and adjusted in a clinic. The preference for the trained settings was not significantly affected by the training of the noise suppression strength, and was moderately but not significantly correlated with the hours of aid use during the training period. Therefore, the customization of compression parameters that is currently performed in the clinic can at least partly be performed in real life listening situations by clients who have been fitted with this trainable aid.

The acoustic and perceptual effects of two noise-suppression algorithms.

Internal noise generated by hearing-aid circuits can be audible and objectionable to aid users, and may lead to the rejection of hearing aids. Two expansion algorithms were developed to suppress internal noise below a threshold level. The multiple-channel algorithm's expansion thresholds followed the 55-dB SPL long-term average speech spectrum, while the single-channel algorithm suppressed sounds below 45 dBA. With the recommended settings in static conditions, the single-channel algorithm provided lower noise levels, which were perceived as quieter by most normal-hearing participants. However, in dynamic conditions "pumping" noises were more noticeable with the single-channel algorithm. For impaired-hearing listeners fitted with the ADRO amplification strategy, both algorithms maintained speech understanding for words in sentences presented at 55 dB SPL in quiet (99.3% correct). Mean sentence reception thresholds in quiet were 39.4, 40.7, and 41.8 dB SPL without noise suppression, and with the single- and multiple-channel algorithms, respectively. The increase in the sentence reception threshold was statistically significant for the multiple-channel algorithm, but not the single-channel algorithm. Thus, both algorithms suppressed noise without affecting the intelligibility of speech presented at 55 dB SPL, with the single-channel algorithm providing marginally greater noise suppression in static conditions, and the multiple-channel algorithm avoiding pumping noises.

Preferred overall loudness. I: Sound field presentation in the laboratory.

This study questions the basic assumption that prescriptive methods for nonlinear, wide dynamic range compression (WDRC) hearing aids should restore overall loudness to normal. Fifteen normal-hearing listeners and twenty-four hearing-impaired listeners (with mild to moderate hearing loss, twelve with and twelve without hearing aid experience) participated in laboratory tests. The participants first watched and listened to video sequences and rated how loud and how interesting the situations were. For the hearing-impaired participants, gain was applied according to the NAL-NL1 prescription. Despite the fact that the NAL-NL1 prescription led to less than normal overall calculated loudness, according to the loudness model of Moore and Glasberg (1997), the hearing-impaired participants rated loudness higher than the normal-hearing participants. The participants then adjusted a volume control to preferred overall loudness. Both normal-hearing and hearing-impaired participants preferred less than normal overall calculated loudness. The results from the two groups of hearing-impaired listeners did not differ significantly.

Preferred overall loudness. II: Listening through hearing aids in field and laboratory tests.

In a laboratory study, we found that normal-hearing and hearing-impaired listeners preferred less than normal overall calculated loudness (according to a loudness model of Moore & Glasberg, 1997). The current study verified those results using a research hearing aid. Fifteen hearing-impaired and eight normal-hearing participants used the hearing aid in the field and adjusted a volume control to give preferred loudness. The hearing aid logged the preferred volume control setting and the calculated loudness at that setting. The hearing-impaired participants preferred, in median, loudness levels of -14 phon re normal for input levels from 50 to 89 dB SPL. The normal-hearing participants preferred close to normal overall loudness. In subsequent laboratory tests, using the same hearing aid, both hearing-impaired and normal-hearing listeners preferred less than normal overall calculated loudness, and larger reductions for higher input levels In summary, the hearing-impaired listeners preferred less than normal overall calculated loudness, whereas the results for the normal-hearing listeners were inconclusive.