Frame Theory for Signal Processing in Psychoacoustics

This review chapter aims to strengthen the link between frame theory and signal processing tasks in psychoacoustics. On the one side, the basic concepts of frame theory are presented and some proofs are provided to explain those concepts in some detail. The goal is to reveal to hearing scientists how this mathematical theory could be relevant for their research. In particular, we focus on frame theory in a filter bank approach, which is probably the most relevant view-point for audio signal processing. On the other side, basic psychoacoustic concepts are presented to stimulate mathematicians to apply their knowledge in this field

Temporal resolution in the auditory system

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Basilar-membrane modularity and the growth of forward masking

Forward masking growth functions were measured for pure-tone maskers and signals at 2 and 6 kHz as a function of the silent interval between the masker and signal. The inclusion of conditions involving short signals and short masker-signal intervals ensured that a wide range of signal thresholds were recorded. A consistent pattern was seen across all the results. When the signal level was below about 35 dB SPL the growth of masking was shallow, so that signal threshold increased at a much slower rate than masker level. When the signal level exceeded this value, the masking function steepened, approaching unity (linear growth) at the highest masker and signal levels. The results are inconsistent with an explanation for forward-masking growth in terms of saturating neural adaptation. Instead the data are well described by a model incorporating a simulation of the basilar-membrane response at characteristic frequency (which is almost linear at low levels and compressive at higher levels) followed by a sliding intensity integrator or temporal window. Taken together with previous results, the findings suggest that the principle nonlinearity in temporal masking may be the basilar membrane response function, and that subsequent to this the auditory system behaves as if it were linear in the intensity domain

Comparison of continuous sampling with active noise cancelation and sparse sampling for cortical and subcortical auditory functional MRI

Purpose: Detecting sound-related activity using functional MRI requires the auditory stimulus to be more salient than the intense background scanner acoustic noise. Various strategies can reduce the impact of scanner acoustic noise, including “sparse” temporal sampling with single/clustered acquisitions providing intervals without any background scanner acoustic noise, or active noise cancelation (ANC) during “continuous” temporal sampling, which generates an acoustic signal that adds destructively to the scanner acoustic noise, substantially reducing the acoustic energy at the participant’s eardrum. Furthermore, multiband functional MRI allows multiple slices to be collected simultaneously, thereby reducing scanner acoustic noise in a given sampling period. Methods: Isotropic multiband functional MRI (1.5 mm) with sparse sampling (effective TR = 9000 ms, acquisition duration = 1962 ms) and continuous sampling (TR = 2000 ms) with ANC were compared in 15 normally hearing participants. A sustained broadband noise stimulus was presented to drive activation of both sustained and transient auditory responses within subcortical and cortical auditory regions. Results: Robust broadband noise-related activity was detected throughout the auditory pathways. Continuous sampling with ANC was found to give a statistically significant advantage over sparse sampling for the detection of the transient (onset) stimulus responses, particularly in the auditory cortex (P < .001) and inferior colliculus (P < .001), whereas gains provided by sparse over continuous ANC for detecting offset and sustained responses were marginal (p ~ 0.05 in superior olivary complex, inferior colliculus, medial geniculate body, and auditory cortex). Conclusions Sparse and continuous ANC multiband functional MRI protocols provide differing advantages for observing the transient (onset and offset) and sustained stimulus responses

Design methodology for a hexarot-based centrifugal high-G simulator

The perceptual salience of a target tone presented in a multitone background is increased by the presentation of a precursor sound consisting of the multitone background alone. It has been proposed that this "enhancement" phenomenon results from an effective amplification of the neural response to the target tone. In this study, we tested this hypothesis in humans, by comparing the auditory steady-state response (ASSR) to a target tone that was enhanced by a precursor sound with the ASSR to a target tone that was not enhanced. In order to record neural responses originating in the brainstem, the ASSR was elicited by amplitude modulating the target tone at a frequency close to 80 Hz. The results did not show evidence of an amplified neural response to enhanced tones. In a control condition, we measured the ASSR to a target tone that, instead of being perceptually enhanced by a precursor sound, was acoustically increased in level. This level increase matched the magnitude of enhancement estimated psychophysically with a forward masking paradigm in a previous experimental phase. We found that the ASSR to the tone acoustically increased in level was significantly greater than the ASSR to the tone enhanced by the precursor sound. Overall, our results suggest that the enhancement effect cannot be explained by an amplified neural response at the level of the brainstem. However, an alternative possibility is that brainstem neurons with enhanced responses do not contribute to the scalp-recorded ASSR

Blood Prestin Levels in Normal Hearing and in Sensorineural Hearing Loss: A Scoping Review

Objectives: Recently, it has been hypothesized that blood prestin concentration levels may reflect cochlear damage and thus serve as an easily measurable, early sensorineural hearing loss (HL) biomarker. This is a scoping review aiming to identify and critically appraise current evidence on prestin blood levels and their temporal variation in rodents and humans with normal hearing and with sensorineural HL. Design: This study was designed and held according to PRISMA Extension for Scoping Reviews (PRISMA-ScR) guidelines. With no limitation with regards to study type, animal and human studies focusing on prestin blood levels in normal hearing and in sensorineural HL were sought in major databases such as Medline, Central Scopus, PROSPERO, and Clinicaltrials.gov. Results were then hand-searched. A data charting form was developed including the parameters of interest. Results: Seven studies focusing on measuring prestin blood levels by means of ELISA in rodents and human subjects with normal hearing and noise-induced, drug-induced, or idiopathic sudden HL were found eligible and were included in the analysis. According to these proof-of-concept studies, prestin can be detected in the circulation of subjects with no HL; however, normal ranges remain unclear. After cochlear damage, blood prestin levels seem to initially rise and then return to near or below baseline. The degree of their change relates with subjects&apos; degree of HL, damaged cochlear region and recovery. Prestin blood levels and their temporal variation seem to correlate with cochlear damage; however, methodological weaknesses, such as small sample size, lack of detailed phenotyping, insufficient exclusion of confounding factors, and short follow-up, do not allow for robust conclusions. Conclusions: Current findings support the value of studying blood prestin levels in normal hearing and HL and highlight a need for larger-scale longitudinal research. © 2021 Lippincott Williams and Wilkins. All rights reserved