Putative Auditory-Evoked Neurophonic Measurements Using a Novel Signal Processing Technique: A Pilot Case Study

With changes to cochlear implant candidacy and improvements in surgical technique, there is a need for accurate intraoperative assessment of low-frequency hearing thresholds during cochlear implantation. In electrocochleography, onset compound action potentials (CAPs) typically allow estimation of auditory threshold for frequencies above 1 kHz, but they are less accurate at lower frequencies. Auditory nerve neurophonic (ANN) waveforms, on the other hand, may overcome this limitation by allowing phase-locked neural activity to be tracked during a prolonged low-frequency stimulus rather than just at its onset (Henry, 1995). Lichtenhan et al. (2013) have used their auditory nerve overlapped waveform (ANOW) technique to measure these potentials from the round windows of cats and guinea pigs, and reported that in guinea pigs these potentials originate in the cochlear apex for stimuli below 70 dB SPL (Lichtenhan et al., 2014). Human intraoperative round window neurophonic measurements have been reported by Choudhury et al. (2012). We have done the same in hearing impaired awake participants, and present here the results of a pilot study in which we recorded responses evoked by 360, 525, and 725 Hz tone bursts from the cochlear promontory of one participant. We also present a modification to the existing measurement technique which halves recording time, extracting the auditory neurophonic by recording a single averaged waveform, and then subtracting from it a 180° group-delayed version of itself, rather than using alternating condensation and rarefaction sound stimuli. We cannot conclude that the waveforms we measured were purely neural responses originating from the apex of the cochlea: as with all neurophonic measurement procedures, the neural responses of interest cannot be separated from higher harmonics of the cochlear microphonic without forward masking, regardless of electrode location, stimuli or post-processing algorithm. In conclusion, the extraction of putative neurophonic waveforms can easily be incorporated into existing electrocochleographic measurement paradigms, but at this stage such measurements should be interpreted with caution

Evaluating speech recognition threshold (SRTn) of the Malay digit triplet test (MDTT) in domestic usage

Online self-screening test using speech audiometry in noise offers a new approach to screen for hearing disability from homes and facilitate in creating hearing awareness to the general public. Therefore, the purpose of this study is to evaluate the speech recognition threshold (SRTn) of the Malay Digit Triplet Test (MDTT) in domestic usage

Normative speech recognition threshold in noise (SRTn) for Malay matrix sentence test (MMST) in open-set format

Speech perception ability in noise is a realistic key indicator of a person’s potential to communicate in real-world situations. The Malay Matrix Sentence Test (MMST) is able to provide information about a listener’s speech perception ability in noise. It can also be implemented in either open or closed-set test format. The main purpose of this study was to obtain normative speech recognition threshold in noise (SRTn) for MMST in the open-set test format

Transtympanic Electrocochleography for the Diagnosis of Ménière's Disease

This paper evaluated the diagnostic power of electrocochleography (ECochG) in detecting Ménière's disease (MD) as compared with two subjective assessment methods, including the clinical guidelines provided by the American Academy of Otolaryngology—Head and Neck Surgery Committee on Hearing Equilibrium and the Gibson score. A retrospective study of 250 suspected MD cases was conducted. The agreement between the three assessment methods was found to be relatively high, with a total reliability being higher than 70%. Participants who tested “positive” with ECochG exhibited a higher occurrence rate of asymmetric hearing threshold as well as the four MD symptoms, namely, vertigo, hearing loss, tinnitus, and aural fullness. The “positive” ECochG group also showed a high correlation between the ECochG measures in response to stimuli at adjacent frequency ranges, suggesting that the interfrequency ECochG correspondence may be sensitive to the presence of endolymphatic hydrops and thus may serve as a useful diagnostic marker for MD

Development of the Malay digit triplet test via headphones and telephones as a national hearing screening tool in Malaysia

Introduction: This study aimed to develop a self-administered hearing screening test using digit triplets in Malay (MDTT) to be used as a national hearing screening tool via internet and telephone landlines in Malaysia. Methods: Recordings of disyllabic Malay digits by a female Malay native speaker were used together with a speech shaped stationary noise (TSN). The test stimuli were normalized using responses from twenty normal hearing native Malay speakers. The data were used to produce eight equivalent test lists. An additional twenty normal hearing native Malay speakers were recruited to test the lists equivalency. Forty six listeners with varying levels of hearing were recruited to validate the tests. ROC analysis was done to identify the pass and refer cut-off limits. Results: No statistical differences were found between lists for both test conditions. The evaluation in fixed SNRs resulted in a mean speech reception threshold (SRT) of -11.3 ± 0.34 dB SNR for headphone and -10.24 ± 0.1 dB SNR for telephone applications. A significant main effect of type of transducer was observed in both normal and hearing impaired groups. The cut off for refer, sensitivity and specificity for the tests using telephones are (-5.8dB, 80.8%, 95%) and headphones (-9.8dB, 80.8%, 100%). Conclusions: The MDTT was successfully developed and the normative values are comparable to other versions of the digit triplet tests. The MDTT showed high sensitivity and specificity and can be made available to any Malay speaking public via telephone and internet

Characteristics of disfluency clusters in adults who stutter

Background/Aims: The purpose of this study was to examine characteristics of disfluency clusters in adults who stutter (AWS) and to compare these characteristics to those previously reported for children who stutter (CWS). Method: The spontaneous speech of ten AWS was sampled and organized according to utterance length in syllables. The overall number and type of disfluency clusters occurring in each sample were determined. Results: Findings indicated that utterances containing disfluency clusters were significantly longer than fluent utterances and the occurrence of disfluency clusters was correlated with overall percentage of disfluency. Conclusion: The results obtained in the present study for AWS tend to parallel those found for CWS and serve to validate their occurrence as feature of the disorder of stuttering

Development of an adaptive low-pass filtered speech test for the identification of auditory processing disorders

Objective: One type of test commonly used to examine auditory processing disorders (APD) is the low-pass filtered speech test (LPFST), of which there are various versions. In LPFSTs, a monaural, low-redundancy speech sample is distorted by using filtering to modify its frequency content. Due to the richness of the neural pathways in the auditory system and the redundancy of acoustic information in spoken language, a normal listener is able to recognize speech even when parts of the signal are missing, whereas this ability is often impaired in listeners with APD. One limitation of the various versions of the LPFST is that they are carried out using a constant level of low-pass filtering (e.g. a fixed 1 kHz corner frequency) which makes them prone to ceiling and floor effects. The purpose of this study was to counter these effects by modifying the LPFST using a computer-based adaptive procedure, and to evaluate the performance of normal-hearing participants of varying ages on the test. Methods: In this preliminary study, 33 adults and 30 children (aged 8 to 11 years) with no known history of listening difficulties were tested. The University of Canterbury Adaptive Speech Test (UCAST) platform was used to administer a four-alternative forced-choice adaptive test that altered a low-pass filter (LPF) to track the corner frequency at which participants correctly identified a certain percentage of the word stimuli. Results: Findings on the University of Canterbury Adaptive Speech Test – Filtered Words (UCAST-FW) indicated a significant maturational effect. Adult participants performed significantly better on the UCAST-FW in comparison to the child participants. The UCAST-FW test was reliable over repeated administrations. Conclusions: An adaptive low-pass filtered speech test such as the UCAST-FW is sensitive to maturational changes in auditory processing ability

An exploration of dichotic listening among adults who stutter

A pilot investigation of dichotic listening of CV stimuli was undertaken using seven adults who stutter (AWS) and a comparison group of seven adults who do not stutter (AWNS). The aim of this research was to investigate whether AWS show a difference in the strength of the right ear advantage (REA) in both undirected and directed attention tasks when compared to AWNS. The undirected attention task involved manipulating the interaural intensity difference (IID) of the CV stimuli presented to each ear. The CV stimuli were presented with equal intensity for the directed attention task. The undirected attention results indicated that both AWS and AWNS have a REA for processing speech information, with a primary difference observed between groups in regard to the IID point at which a REA shifts to a LEA. This crossing-over point occurred earlier for AWS, indicating a stronger right hemisphere involvement for the processing of speech compared to AWNS. No differences were found between groups in the directed attention task. The differences and similarities observed in dichotic listening between the two groups are discussed in regard to hemispheric specialization in the processing of speech

Environmental Sound Perception of Cochlear Implant Users

Introduction Most current adult cochlear implant (CI) users achieve higher open-set speech perception scores post- surgery than pre- surgery, a factor which greatly improves their overall quality of life. There is little published research assessing the ability of CI users to identify environmental sounds, an important skill which also impacts upon a patient’s quality of life. This study compared adult CI users to normally hearing (NH) listeners in their ability to identify various environmental sounds. The Environmental Sounds Perception Test (ESPT) developed for this study was more difficult and more comprehensive than those used in current studies, in order to reduce the likelihood of any potential ceiling effect affecting the results. It was hypothesised that the CI users would score lower than similarly-aged NH listeners on the ESPT