Hearing threshold estimation using concurrent measurement of distortion product otoacoustic emissions and auditory steady-state responses

Multichannel search strategy for improving the detection of auditory steady-state response

Auditory steady-state response (ASSR) is useful for hearing threshold estimation. The ASSR is usually detected with objective response detectors (ORD). The performance of these detectors depends on the signal-to-noise ratio (SNR) as well as the signal length. Since it is undesirable to increase the signal length, then, this work provides a multivariate technique for improving the SNR and consequently the detection power. We propose the insertion of a short calibration step before the detection protocol, in order to perform a search among the available electroencephalogram (EEG) derivations and select the derivation with the highest SNR. The ORD used in this work was the magnitude-squared coherence (MSC). The standard detection protocol is to use the same EEG derivation in all exams. Using 22-scalp positions, the new technique achieved a detection rate higher than that obtained in 99.13% of the standard detection protocol. When restrictions were applied to the search, a superior performance was achieved. Thus, the technique proposed was able to track the best EEG derivations before exams and seems to be able to deal with the variability between individuals and between sessions.

Does airborne ultrasound lead to activation of the auditory cortex?

As airborne ultrasound can be found in many technical applications and everyday situations, the question as to whether sounds at these frequencies can be heard by human beings or whether they present a risk to their hearing system is of great practical relevance. To objectively study these issues, the monaural hearing threshold in the frequency range from 14 to 24 kHz was determined for 26 test subjects between 19 and 33 years of age using pure tone audiometry. The hearing threshold values increased strongly with increasing frequency up to around 21 kHz, followed by a range with a smaller slope toward 24 kHz. The number of subjects who could respond positively to the threshold measurements decreased dramatically above 21 kHz. Brain activation was then measured by means of magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) and with acoustic stimuli at the same frequencies, with sound pressure levels (SPLs) above and below the individual threshold. No auditory cortex activation was found for levels below the threshold. Although test subjects reported audible sounds above the threshold, no brain activity was identified in the above-threshold case under current experimental conditions except at the highest sensation level, which was presented at the lowest test frequency.

Drug-induced ototoxicity: Mechanisms, Pharmacogenetics, and protective strategies

Drug ototoxicity limits the quality of life of patients after treatment, having serious consequences, especially for psychosocial development of children. Although the ototoxicity of many drugs resolves after treatment discontinuation, the use of platinum derivatives and aminoglycosides is associated with permanent hearing loss. In this review, we have listed ototoxic drugs and the mechanisms by which they damage the ears. Moreover, possible protective strategies and important methods for early detection of ototoxic effects are discussed.

Concurrent measures of contralateral suppression of transient-evoked otoacoustic emissions and of auditory steady-state responses

Contralateral suppression of otoacoustic emissions (OAEs) is frequently used to assess the medial olivocochlear (MOC) efferent system, and may have clinical utility. However, OAEs are weak or absent in hearing-impaired ears, so little is known about MOC function in the presence of hearing loss. A potential alternative measure is contralateral suppression of the auditory steady-state response (ASSR) because ASSRs are measurable in many hearing-impaired ears. This study compared contralateral suppression of both transient-evoked otoacoustic emissions (TEOAEs) and ASSRs in a group of ten primarily older adults with either normal hearing or mild sensorineural hearing loss. Responses were elicited using 75-dB peak sound pressure level clicks. The MOC was activated using contralateral broadband noise at 60 dB sound pressure level. Measurements were made concurrently to ensure a consistent attentional state between the two measures. The magnitude of contralateral suppression of ASSRs was significantly larger than contralateral suppression of TEOAEs. Both measures usually exhibited high test-retest reliability within a session. However, there was no significant correlation between the magnitude of contralateral suppression of TEOAEs and of ASSRs. Further work is needed to understand the role of the MOC in contralateral suppression of ASSRs.

Hearing impairment and language delay in infants: Diagnostics and genetics

This overview study provides information on important phoniatric and audiological aspects of early childhood hearing and language development with the aim of presenting diagnostic and therapeutic approaches. The article first addresses the universal newborn hearing screening that has been implemented in Germany for all infants since January 2009. The process of newborn hearing screening from the maternity ward to confirmation diagnostics is presented in accordance with a decision by the Federal Joint Committee (G-BA). The second topic is pediatric audiology diagnostics. Following confirmation of a permanent early childhood hearing disorder, the search for the cause plays an important role. Hereditary hearing disorders and intrauterine cytomegalovirus (CMV) infection, probably the most common cause of an acquired hearing disorder, are discussed and compared with the most common temporary hearing disorder, otitis media with effusion, which in some cases is severe enough to be relevant for hearing and language development and therefore requires treatment. The third topic covered in this article is speech and language development in the first 3 years of life, which is known today to be crucial for later language development and learning to read and write. There is a short overview and introduction to modern terminology, followed by the abnormalities and diagnostics of early speech and language development. Only some aspects of early hearing and language development are addressed here. Important areas such as the indication for a cochlear implant in the first year of life or because of unilateral deafness are not included due to their complexity.

Distortion product otoacoustic emissions upon ear canal pressurization

The purpose of this study was to quantify the change in distortion product otoacoustic emission (DPOAE) level upon ear canal pressurization. DPOAEs were measured on 12 normal-hearing human subjects for ear canal static pressures between -200 and +200 daPa in (50 ± 5) daPa steps. A clear dependence of DPOAE levels on the pressure was observed, with levels being highest at the maximum compliance of the middle ear, and decreasing on average by 2.3 dB per 50 daPa for lower and higher pressures. Ear canal pressurization can serve as a tool for improving the detectability of DPOAEs in the case of middle-ear dysfunction.

Providing Audiological Services to Individuals With Aphasia: Considerations, Preliminary Recommendations, and a Call for Research

Purpose

The populations most susceptible to hearing loss and to aphasia overlap substantially, creating a high likelihood that audiologists will be called on to assess and treat individuals with aphasia. There is, however, scarce research available to guide best practices for serving this population.

Method

The available relevant literature is reviewed to summarize what is already known, providing basic information about aphasia and its potential impact on audiological diagnostic and intervention processes.

Conclusion

Suggestions for managing aphasia in the clinical audiology setting are provided, and areas of needed research are identified so that services for individuals with aphasia can be optimized.