Reconstruction of sound driven, actively amplified and spontaneous motions within the tree cricket auditory organ

Hearing consists of a delicate chain of events. Sound is first captured by an eardrum or similar organ which is set into vibrations, these vibrations must then be transmitted to sensory cells in a manner that opens mechanosensory channels generating an electrical signal. Studying this process is challenging. Auditory vibrations are in the nano- to picometer-scale and occur at fast temporal scales of milli to microseconds. Finally, most of this process occurs within the body of the animal where it is inaccessible to conventional measurement techniques. For instance, even in crickets, a century-old auditory model system, it is unclear how sound evoked vibrations are transmitted to sensory neurons. Here, we use optical coherence tomography (OCT) to measure how vibrations travel within the auditory organ of the western tree cricket (Oecanthus californicus). We also measure the reversal of this process as mechanosensory cells generate spontaneous oscillations and amplify sound-evoked vibrations. Most importantly, we found that while the mechanosensory neurons were not attached to the peripheral sound collecting structures, they were mechanically well-coupled through acoustic trachea. Thus, the acoustic trachea are not merely conduits for sound but also perform a mechanical function. Our results generate several insights into the similarities between insect and vertebrate hearing, and into the evolutionary history of auditory amplification.

Auditory-Motor Perturbations of Voice Fundamental Frequency: Feedback Delay and Amplification

Purpose Gradual and sudden perturbations of vocal fundamental frequency ( f o ), also known as adaptive and reflexive f o perturbations, are techniques to study the influence of auditory feedback on voice f o control mechanisms. Previous vocal f o perturbations have incorporated varied setup-specific feedback delays and amplifications. Here, we investigated the effects of feedback delays (10–100 ms) and amplifications on both adaptive and reflexive f o perturbation paradigms, encapsulating the variability in equipment-specific delays (3–45 ms) and amplifications utilized in previous experiments. Method Responses to adaptive and reflexive f o perturbations were recorded in 24 typical speakers for four delay conditions (10, 40, 70, and 100 ms) or three amplification conditions (−10, +5, and +10 dB relative to microphone) in a counterbalanced order. Repeated-measures analyses of variance were carried out on the magnitude of f o responses to determine the effect of feedback condition. Results There was a statistically significant effect of the level of auditory feedback amplification on the response magnitude during adaptive f o perturbations, driven by the difference between +10- and −10-dB amplification conditions (hold phase difference: M = 38.3 cents, SD = 51.2 cents; after-effect phase: M = 66.1 cents, SD = 84.6 cents). No other statistically significant effects of condition were found for either paradigm. Conclusions Experimental equipment delays below 100 ms in behavioral paradigms do not affect the results of f o perturbation paradigms. As there is no statistically significant difference between the response magnitudes elicited by +5- and +10-dB auditory amplification conditions, this study is a confirmation that an auditory feedback amplification of +5 dB relative to microphone is sufficient to elicit robust compensatory responses for f o perturbation paradigms.

Тhe effects of auditory amplification on subjective assessments of hearing impairment and anxiety in people with presbycusis

Introduction/Objective. Presbycusis, elderly hearing loss, is a progressive, bilateral sensoryneural hearing loss characterized by reduced sensitivity of hearing and understanding speech in a noisy environment, thereby impairing communication and inducing anxiety. The objective was to examine the impact of hearing amplification on subjective hearing disability assessment and anxiety in people with presbycusis. Method. Sample consisted of 120 respondents aged 47?85 with presbycusis, 60 subjects with and 60 subjects with no auditory amplification. The standardized Hearing Handicap Inventory for the Elderly and the Spielberger State Trait Anxiety Inventory were used in the study. Results. In subjects with hearing amplification, test/retest has no statistical significance in the STAI and HHIE scales and subscales, except the HHIE-S (p = 0.004) with a lower score on the retest. Respondents in whom hearing amplification was performed during the year was statistically significant in HHIE (p = 0.016), HHIE-S (p = 0.004) and STAI-S (p = 0.029) which speaks of favorable effect of hearing amplification. In the group with no hearing amplification, statistical significance was observed in relation to the HHIE scores (p = 0.002), HHIE-E (p = 0.000), STAI (p = 0.000), STAI-S (p = 0.001) and STAI-T (p = 0.001) and it was noticed that anxiety, loss of emotional contacts, and more pronounced degree of hearing impairment were the result of unassisted hearing rehabilitation. Conclusion. Audiological practice should include tests for assessment of hearing disability and anxiety in order to preserve health in later life.

Early Vocal Development in Tactually Aided Children With Severe-Profound Hearing Loss

The vocalizations of six children with severe-profound hearing loss were audio-recorded in two conditions during individual speech-language intervention sessions: (a) auditory amplification alone, and (b) auditory amplification plus the Tactaid II, a two-channel vibrotactile device (Franklin, 1986). Utterances were categorized according to the infraphonological framework described by Oller (1980, 1986) and Oller and Lynch (1992). Vocalizations were categorized in a developmental framework relative to mature speech. Those utterances containing well-formed consonant-vowel syllables were transcribed with broad phonetic transcription and analyzed at both the syllabic and segmental levels. Statistically significant differences were found between the two conditions for vocal volubility (i.e., quantity of vocalizations produced); subjects vocalized more when using both auditory amplification and the Tactaid II together than with auditory amplification alone. Trends in the early vocal development of these children with severe-profound hearing loss are described at the infraphonologic, segmental, and syllabic levels.