Auditory Brainstem Responses in the C57BL/6J Fragile X Syndrome Knockout Mouse Model

Sensory hypersensitivity, especially in the auditory system, is a common symptom in Fragile X Syndrome (FXS), the most common monogenic form of intellectual disability. However, linking phenotypes across genetic background strains of mouse models has been a challenge and could underly some of the issues with translatability of drug studies to the human condition. This study is the first to characterize the auditory brainstem response (ABR), a minimally invasive physiological readout of early auditory processing that is also used in humans, in a commonly used mouse background strain model of FXS, C57BL/6J. We measured morphological features of pinna and head and used ABR to measure hearing range, monaural and binaural auditory responses in hemizygous males, homozygous females and heterozygous females compared to wildtype mice. Consistent with previous work we showed no difference in morphological parameters across genotypes or sexes. Male FXS mice had increased threshold for high frequency hearing at 64 kHz compared to wildtype males, while females had no difference in hearing range between genotypes. In contrast, female homozygous FXS mice had decreased amplitude of wave IV of the monaural ABR, while there was no difference in males for amplitudes and no change in latency of ABR waveforms across sexes and genotypes. Lastly, FXS males had increased latency of the binaural interaction component (BIC) at 0 ITD compared to wildtype males. These findings further clarify auditory brainstem processing in FXS by adding more information across genetic background strains allowing for a better understanding of shared phenotypes.

Hearing, echolocation, and beam steering from day 0 in tongue-clicking bats

Little is known about the ontogeny of lingual echolocation. We examined the echolocation development of Rousettus aegyptiacus , the Egyptian fruit bat, which uses rapid tongue movements to produce hyper-short clicks and steer the beam's direction. We recorded from day 0 to day 35 postbirth and assessed hearing and beam-steering abilities. On day 0, R. aegyptiacus pups emit isolation calls and hyper-short clicks in response to acoustic stimuli, demonstrating hearing. Auditory brainstem response recordings show that pups are sensitive to pure tones of the main hearing range of adult Rousettus and to brief clicks. Newborn pups produced clicks in the adult paired pattern and were able to use their tongues to steer the sonar beam. As they aged, pups produced click pairs faster, converging with adult intervals by age of first flights (7–8 weeks). In contrast with laryngeal bats, Rousettus echolocation frequency and duration are stable through to day 35, but shift by the time pups begin to fly, possibly owing to tongue-diet maturation effects. Furthermore, frequency and duration shift in the opposite direction of mammalian laryngeal vocalizations. Rousettus lingual echolocation thus appears to be a highly functional sensory system from birth and follows a different ontogeny from that of laryngeal bats.

Hearing Ability of Prairie Voles (Microtus ochrogaster)

Hearing ability of mammals can be impacted by many factors including social cues, environment, and physical properties of animal morphology. Despite being used commonly to study social behaviors, the hearing ability of the monogamous prairie vole (Microtus ochrogaster) has never been fully characterized. In this study, we measure morphological head and pinna features and use auditory brainstem responses to measure hearing ability of prairie voles characterizing monaural and binaural hearing and hearing range. Additionally, we measured unbonded male and female voles to characterize differences due to sex. We found that prairie voles have intermediate hearing ability with an optimal hearing range of 8 to 32 kHz, robust binaural hearing ability, and characteristic monaural ABRs. We show no differences between the sexes for binaural hearing or hearing range, however female voles have increased amplitude of peripheral ABR waves I and II and increased latency of wave IV. Our results confirm that prairie voles have both low and high frequency hearing, binaural hearing capability, and despite biparental care and monogamy, differences in processing of sound information between the sexes. These data further highlight the necessity to understand sex-specific differences in neural processing that may underly variability in behavioral responses between sexes.

Critical Repetition Rates for Perceptual Segregation of Time-Varying Auditory, Visual and Vibrotactile Stimulation

What sound quality has led to exclude infrasound from sound in the conventional hearing range? We examined whether temporal segregation of pressure pulses is a distinctive property and evaluated this perceptual limit via an adaptive psychophysical procedure for pure tones and carriers of different envelopes. Further, to examine across-domain similarity and individual covariation of this limit, here called the critical segregation rate (CSR), it was also measured for various periodic visual and vibrotactile stimuli. Results showed that sequential auditory or vibrotactile stimuli separated by at least ~80‒90 ms (~11‒12-Hz repetition rates), will be perceived as perceptually segregated from one another. While this limit did not statistically differ between these two modalities, it was significantly lower than the ~150 ms necessary to perceptually segregate successive visual stimuli. For the three sensory modalities, stimulus periodicity was the main factor determining the CSR, which apparently reflects neural recovery times of the different sensory systems. Among all experimental conditions, significant within- and across-modality individual CSR correlations were observed, despite the visual CSR (mean: 6.8 Hz) being significantly lower than that of both other modalities. The auditory CSR was found to be significantly lower than the frequency above which sinusoids start to elicit a tonal quality (19 Hz; recently published for the same subjects). Returning to our initial question, the latter suggests that the cessation of tonal quality — not the segregation of pressure fluctuations — is the perceptual quality that has led to exclude infrasound (sound with frequencies < 20 Hz) from the conventional hearing range.

Application of the Electrostatic Micro-Speakers for Producing Audible Directional Sound

In recent years, the demand for control of sound power and radiation patterns in personal messaging, calls, automotive entertainment, and gaming has brought a new interest in the audio world. The aim of this paper is to investigate the feasibility of producing the sound waves in the audible range and directing them in the desired listening zone by electrostatic micro-speakers. Therefore, a capacitive circular micro-plate has been modeled as an electrostatic micro-speaker. Then a Bessel panel array has been developed using a number of these plates arranged in a square array. The equations governing the vibrations of the micro-speaker’s diaphragm, as well as radiation pattern of the sound waves, have been introduced and solved. The results have shown that the Micro-Electro Mechanical Systems (MEMS) electrostatic diaphragms have the capability of producing the directional sound in the human hearing range. Moreover, we have investigated the effect of different excitation frequencies, radii size and the number of the diaphragms as well as the inter-element spacing on the sound radiation pattern of the Bessel panel array.

Hearing thresholds of small native Australian mammals – red-tailed phascogale (Phascogale calura), kultarr (Antechinomys laniger) and spinifex hopping-mouse (Notomys alexis)

Hearing is essential for communication, to locate prey and to avoid predators. We addressed the paucity of information regarding hearing in Australian native mammals by specifically assessing the hearing range and sensitivity of the red-tailed phascogale (Phascogale calura), the kultarr (Antechinomys laniger) and the spinifex hopping-mouse (Notomys alexis). Auditory brainstem response (ABR) audiograms were used to estimate hearing thresholds within the range of 1–84 kHz, over a dynamic range of 0–80 dB sound pressure level (SPL). Phascogales had a hearing range of 1–40 kHz, kultarrs 1–35 kHz and hopping-mice 1–35 kHz, with a dynamic range of 17–59 dB SPL, 20–80 dB SPL and 30–73 dB SPL, respectively. Hearing for all species was most sensitive at 8 kHz. Age showed no influence on optimal hearing, but younger animals had more diverse optimal hearing frequencies. There was a relationship between males and their optimal hearing frequency, and greater interaural distances of individual males may be related to optimal hearing frequency. Because nocturnal animals use high-range hearing for prey or predator detection, our study suggests this may also be the case for the species examined in this study. Future studies should investigate their vocalizations and behaviour in their natural environments, and by exposing them to different auditory stimuli.

Focused Audification and the optimization of its parameters

We present a sonification method which we call Focused Audification (FA; previously: Augmented Audification) that allows to expand pure audification in a flexible way. It is based on a combination of single-side-band modulation and a pitch modulation of the original data stream. Based on two free parameters, the sonification’s frequency range is adjustable to the human hearing range and allows to interactively zoom into the data set at any scale. The parameters have been adjusted in a multimodal experiment on cardiac data by laypeople. Following from these results we suggest a procedure for parameter optimization to achieve an optimal listening range for any data set, adjusted to human speech.

An Update on Applications of Power Ultrasound in Drying Food: A Review

Ultrasound is sound waves with above the human hearing range frequency that is approximately 20 kHz. Application of power ultrasound in combination with other food processing methods including drying, is considered to be an emerging and promising technology. The use of novel non-thermal technologies, such as power ultrasound, is suitable to facilitate the drying of heat sensitive food materials. Ultrasound enhance heat and mas transfer which result in faster moisture removal during drying due to heating, vibration and synergistic effects. These effects could lead to product quality preservation in terms of color, texture, vitamin C and antioxidants content, by the use of milder drying conditions, and in some cases can promote better energy efficiency. In this article, after a brief review on the history of ultrasonic drying, different methods are categorized and combinations of ultrasound with novel drying methods and their effects on phytochemicals are discussed with the focus on the recently published articles. Studies showed that the quality of ultrasonically dried products was usually higher than conventionally dried products. However, the effect of ultrasonic drying on the texture and nutritional value of the products should be further investigated.