Octave Frequency Research Articles

Broadband Scalable Antenna Arrays With Constant Beamwidths Fed by Frequency-Selective Networks

A novel concept of broadband scalable antenna arrays that allows achieving constant beamwidths across one frequency octave has been proposed. The presented antenna arrays consist of an odd number of broadband antenna elements equally spaced and fed by a frequency-selective feeding network. The feeding network gradually switches the signal between the radiating elements across the bandwidth. The required frequency characteristics for such a selective power divider have been shown and its circuit realization has been proposed. The presented concept has been verified by the design and measurements of an antenna array consisting of five radiating elements in which the beamwidth of around 24° is achieved. The developed antenna operates in the 2–4-GHz frequency range. Moreover, the presented concept has been extended showing the possibility of designing antenna arrays having an arbitrary odd number of effectively radiating elements and constant beamwidths over one frequency octave.

Assessing auditory evoked potentials of wild harbor porpoises (Phocoena phocoena).

Testing the hearing abilities of marine mammals under water is a challenging task. Sample sizes are usually low, thus limiting the ability to generalize findings of susceptibility towards noise influences. A method to measure harbor porpoise hearing thresholds in situ in outdoor conditions using auditory steady state responses of the brainstem was developed and tested. The method was used on 15 live-stranded animals from the North Sea during rehabilitation, shortly before release into the wild, and on 12 wild animals incidentally caught in pound nets in Denmark (inner Danish waters). Results indicated that although the variability between individuals is wide, the shape of the hearing curve is generally similar to previously published results from behavioral trials. Using 10-kHz frequency intervals between 10 and 160 kHz, best hearing was found between 120 and 130 kHz. Additional testing using one-third octave frequency intervals (from 16 to 160 kHz) allowed for a much faster hearing assessment, but eliminated the fine scale threshold characteristics. For further investigations, the method will be used to better understand the factors influencing sensitivity differences across individuals and to establish population-level parameters describing hearing abilities of harbor porpoises.

Modelling total weighted vibration of a trailer seat pulled by a two-wheel tractor consumed diesel–biodiesel fuel blends using ANFIS methodology

The application of adaptive neural-fuzzy inference system (ANFIS) to predict the total weighted vibration acceleration of a trailer seat pulled by a two-wheel tractor is set out in the present paper. The vibration acceleration signals were obtained in a field experiment using a 9.5 kW two-wheel tractor. Three accelerometers were installed at three orthogonal directions according to ISO 2631-1 standard on the trailer seat for measuring and recording the vibration acceleration signals. The two-wheel tractor consumed diesel–biodiesel fuel blends, and the engine speed and gear ratio were varied to cover normal range of operation in transportation conditions on asphalt rural road. The digital recorded vibration acceleration signals in time domain were converted to the frequency domain using Fast Fourier Transform algorithm, and the one-third octave frequency bands were obtained. The one-third octave frequencies were weighted according to the ISO standard. Altogether, 100 patterns were generated for training and evaluation of ANFIS. The input parameters of ANFIS were the tractor engine speed, transmission gear ratio of the tractor and fuel blend type, and the output parameter was the trailer seat total weighted vibration acceleration. The ANFIS structure was designed based on the grid partition, fuzzy c-means clustering and subtractive clustering. The results revealed that the ANFIS with subtractive clustering method was the best for accurate prediction of the total weighted vibration acceleration of the trailer seat. The number of rules, root-mean-square error (RMSE) of train, RMSE of test, correlation coefficient (R) of train and R of test values for the optimized structure were 5, 0.1479, 0.2141, 0.9175 and 0.8804, respectively.

The effect of tactile cues on auditory stream segregation ability of musicians and nonmusicians.

(ProQuest: ... denotes formulae omitted.)Western music is often composed of multiple melodic streams that combine to produce a complex structure that gives a particular piece its unique depth and quality. In order to appreciate the interplay of melodic streams, listeners need to be able to first segregate them. Unfortunately, people with hearing loss typically experience great difficulty in doing so primarily due to an impoverishment of their perceptual cues (Oxenham, 2008). This makes music appreciation very challenging for these listeners. For hearing-impaired people whose auditory pathway is fundamentally limited, such as those who use a cochlear implant, it is important to explore sensory substitution as a possible means of enhancing stream segregation and music perception. Recent studies have shown that visual cues can aid hearing-impaired people, and more specifically cochlear implant listeners, in better segregating two musical streams (Innes-Brown, Marozeau, & Blamey, 2011; Marozeau, InnesBrown, Grayden, Burkitt, & Blamey, 2010). We therefore hypothesize that tactile information can be used in a similar way. This paper describes a first study which tests the effect of tactile cues on segregation ability in normal hearing listeners as function of their musical background.Segregation of a melodic stream is made possible by both bottom-up and top-down processes. Bottom-up processes are derived from perceptual cues such as pitch, timbre, and loudness (Bregman, 1990; Marozeau, Innes-Brown, & Blamey, 2010). Topdown processes are derived from cognitive processes involving memory, expectation, musical training, and attention (Carlyon, Cusack, Foxton, & Robertson, 2001). Auditory stream segregation can also be influenced by cross-modal interaction (Carlyon, Plack, Fantini, & Cusack, 2003). Marozeau et al. (2010) have demonstrated that visual cues can improve the streaming ability in both musicians and nonmusicians. Carlyon et al. (2003) has also demonstrated both cross-modal and nonsensory influences on auditory streaming.It is not uncommon for a listener to describe the sensation of feeling Tactile information can add to temporal cues emphasizing the rhythm within a piece (Fraisse, 1981), and can generate a strong sensation of rhythm on its own (Brochard, Touzalin, Despres, & Dufour, 2008). Huang, Gamble, Sarnlertsophon, Wang, and Hsiao (2013) demonstrated that meter is perceived similarly well (70%-85%) when either tactile or auditory cues are presented alone, and that in bimodal mode auditory and tactile cues are integrated to produce coherent meter percepts. It might therefore be hypothesized that tactile information can have an effect on the perception of the musical streams.Musical training is known to have a positive effect on segregation ability (Strait, Kraus, Parbery-Clark, & Ashley, 2010). The effect of cross-modal information on stream segregation can therefore interact with musical training. In order to isolate and understand the interaction between tactile cues and auditory stream segregation ability normal hearing listeners with and without musical experience were assessed.MethodParticipantsTwenty-four participants (12 musicians and 12 nonmusicians, with approximate age average of 27 years old, ranging from 21 to 35 years old) were recruited using social networks in the musician and nonmusician communities. All musicians were full-time professional performers. Nine of them had a formal tertiary education in music and could read music proficiently. The other three were professional flamenco players with an expert level of musicianship but a weaker ability to read music. All the nonmusician participants were unable to play an instrument, and had limited musical training. All participants reported normal hearing and had hearing thresholds at octave frequencies from 125 Hz to 8 kHz below 20 dB HL. Participants also reported normal tactile sensation in their fingertips. …

Perception of Changes in Spectrum and Envelope of Musical Signals vs Auditory Fatigue

AbstractThe paper presents results of research on an influence of listening fatigue on the detection of changes in spectrum and envelope of musical samples. The experiment was carried out under conditions which normally exist in a studio or on the stage when sound material is recorded and/or mixed. The equivalent level of presented sound samples is usually 90 dB and this is an average value of sound level existing in control room at various recording activities. Such musical material may be treated as a noise so Temporary Threshold Shift phenomenon may occur after several sessions and this may lead to a listening fatigue effect. Fourteen subjects participated in the first part of the experiment and all of them have the normal hearing thresholds. The stimuli contained the musical material with introduced changes in sound spectrum up to ±6 dB in low (100 Hz), middle (1 kHz) and high frequency (10 kHz) octave bands. In the second part of research five subjects listened to musical samples with introduced envelope changes up to ±6 dB in interval of 1 s. The time of loud music exposure was 60, 90 and 120 minutes and this material was completely different from the tested samples. It turned out that listening to the music with an Leq= 90 dB for 1 hour influences the hearing thresholds for middle frequency region (about 1-2 kHz) and this has been reflected in a perception of spectral changes. The perceived peaks/notches of 3 dB have the detection ability at 70% and the changes of low and high ranges of spectrum were perceived at the similar level. After the longer exposure, the thresholds shifted up to 4.5 dB for the all investigated stimuli. It has been also found that hearing fatigue after 1 hour of a listening influences the perception of envelope which gets worse of 2 dB in comparison to the fresh-ear listening. When time of listening to the loud music increases, the changes in envelopes which can be detected rise to the value of 6 dB after 90-minutes exposure and it does not increase with further prolongation of listening time.

The Role of Age-Related Declines in Subcortical Auditory Processing in Speech Perception in Noise.

Older adults, even those without hearing impairment, often experience increased difficulties understanding speech in the presence of background noise. This study examined the role of age-related declines in subcortical auditory processing in the perception of speech in different types of background noise. Participants included normal-hearing young (19 – 29 years) and older (60 – 72 years) adults. Normal hearing was defined as pure-tone thresholds of 25 dB HL or better at octave frequencies from 0.25 to 4 kHz in both ears and at 6 kHz in at least one ear. Speech reception thresholds (SRTs) to sentences were measured in steady-state (SS) and 10-Hz amplitude-modulated (AM) speech-shaped noise, as well as two-talker babble. In addition, click-evoked auditory brainstem responses (ABRs) and envelope following responses (EFRs) in response to the vowel /ɑ/ in quiet, SS, and AM noise were measured. Of primary interest was the relationship between the SRTs and EFRs. SRTs were significantly higher (i.e., worse) by about 1.5 dB for older adults in two-talker babble but not in AM and SS noise. In addition, the EFRs of the older adults were less robust compared to the younger participants in quiet, AM, and SS noise. Both young and older adults showed a “neural masking release,” indicated by a more robust EFR at the trough compared to the peak of the AM masker. The amount of neural masking release did not differ between the two age groups. Variability in SRTs was best accounted for by audiometric thresholds (pure-tone average across 0.5–4 kHz) and not by the EFR in quiet or noise. Aging is thus associated with a degradation of the EFR, both in quiet and noise. However, these declines in subcortical neural speech encoding are not necessarily associated with impaired perception of speech in noise, as measured by the SRT, in normal-hearing older adults.

Effects of Threshold Adjustment on Speech Perception in Nucleus Cochlear Implant Recipients.

The objective of this study was to investigate the impact of using smaller and larger electric dynamic ranges on speech perception, aided thresholds, and subjective preference in cochlear implant (CI) subjects with the Nucleus device. Data were collected from 19 adults using the Nucleus CI system. Current levels (CLs) used to set threshold stimulation levels (T-levels) were set above or below the measured hearing thresholds to create smaller or larger electric output dynamic ranges, respectively, whereas the upper stimulation level (C-level) was fixed. The base (unadjusted) condition was compared against two conditions with higher T-levels (compression), by 30% and 60% of the measured hearing dynamic range, and three conditions with lower T-levels (expansion), by 30%, 60%, and 90% of the measured hearing dynamic range. For each subject, the clinical CL units were adjusted on each electrode to achieve these conditions. The slow-acting dynamic acoustic gains of ADRO and Autosensitivity™ were enabled. Consonant-nucleus-consonant (CNC) word scores were measured in quiet at 50 dB and 60 dB SPL presentation levels. The signal-to-noise ratios (SNRs) for 50% understanding of sentences in noise were measured for sentences presented at 55 dB and 65 dB SPL in 4-talker babble noise. Free-field aided thresholds were measured at octave frequencies using frequency-modulated (warble) tones. Thirteen of the 19 subjects had take-home experience with the base and experimental conditions and provided subjective feedback via a questionnaire. There were no significant effects of 30% expansion and 30% compression of the electric dynamic range on scores for words in quiet and SNRs for sentences in noise, at the two presentation levels. There was a significant decrement in scores for words in quiet for 60% and 90% expansion compared with the base condition at the 50 dB and 60 dB SPL presentation levels. The score decrement was much less at 60 dB SPL. For the 50 dB SPL presentation level, the decrements in word scores at 60% and 90% expansion were linearly related to the reduction in CL units required to achieve these experimental conditions, with a greater decrement in scores for a larger CL change. There was a significant increase in SNR for sentences in noise for 60% compression compared with the base condition at the 55 dB and 65 dB SPL presentation levels. There was also a significant increase in SNR for sentences at the 55 dB SPL presentation level for 90% expansion. Aided thresholds were significantly elevated for the three expansion conditions compared with the base condition, although the mean elevation at 30% expansion was only 4 dB. The questionnaire results showed no clear preference for any condition; however, subjects reported a reduced preference for the extreme compression (60%) and expansion (90%) conditions. The results showed that CI subjects using the Nucleus sound processor had no significant change in performance or preference for adjustments in T-levels by ±30% of the hearing dynamic range. In quiet, speech perception scores were reduced for the more marked expansion (60% and 90%) conditions, whereas in noise, performance was poorer for the highest compression (60%) condition. Across subjects, the decrement in scores for words at 50 dB SPL for the 60% and 90% expansion conditions was related to the changes in CL units required for these conditions, with greater decrements for larger changes in levels.

A NOTE ON METHODS FOR THE ESTIMATION OF THE AIRBORNE SOUND INSULATION OF TIMBER FRAME STRUCTURES

Acoustic behavior of structures with wooden elements is nowadays of great interest. At the same time, the estimation of the airborne sound insulation of timber frame structures is a complex procedure which includes the prediction of several resonances and the analysis of a significant decrease of the transmission loss in the low frequency range.Three case studies are presented in the paper. The emphasis is put on the transmission loss in 1/3 octave frequency bands of double leaf structures with gypsum panels, wood studs and a well-damped cavity. Methods of Sharp and Davy are used for the transmission loss prediction. Particular issues are discussed for an asymmetrically sheathed timber frame structure, wood studs with resilient channels and staggered studs.The paper also presents that the weighted sound reduction index is not sufficient quantity for characterizing the airborne sound insulation of timber frame structures. Various methods are employed for the calculation of the transmission loss of a traditional structure on a silicate base. Characteristic differences between a silicate based structure and a timber frame structure are highlighted. The usage of the spectrum adaptation terms is encouraged.The paper intends to be helpful in the field of the transmission loss estimation of double leaf structures with wood studs. Since the acoustic behavior of double leaf structures with wood studs is certainly a complex phenomenon, there is a further need for an improvement of methods for the transmission loss estimation and single number quantities for the evaluation of the sound insulation.

Effect two grades of octane numbers on the performance, exhaust and acoustic emissions of spark ignition engine

This study presents a comparative analysis of performance, exhaust and noise emissions for a one-cylinder, four-stroke, spark-ignition engine powered by gasoline fuels of two different grades of research octane numbers (RONs), namely octane 90, and octane 95. During the experimental works, each fuel test was performed by varying the engine speed within the range from 1000 to 3600rpm. The SI engine was connected to eddy current dynamometer with electronic control unit (ECU), an exhaust gas analyzer and the sound level meter (SLM) to determine engine performance, exhaust emissions, and measuring the sound pressure level (SPL) in decibels (dBA) and one octave frequency bands in the audible human range at different engine speeds, respectively. The experimental results showed that the using gasoline with octane grades higher than the requirement of an engine will decrease the engine performance. On average, the brake power and thermal efficiency for the SI engine fuelled with octane 90 is higher than that of gasoline octane 95 by 6% and 11% respectively, and improvement of BSFC by 14%, which is mainly due to higher heating value. Even though, the volumetric efficiency of octane 95 is more 5% than octane 90 due to higher latent heat and heat capacity. In general, the exhaust emission profiles for NOx and CO of the engine improved for octane 95 by 11% and 17% respectively. On the other side, the HC and CO2 emissions concentration of gasoline octane 90 is lower than that of gasoline octane 95 by 18% and 12% respectively. Finally, the noise levels showed a trend of the increase of disturbing for higher octane number and the increase of divergence between the two values of SPL at higher speed for both fuels.

Neural activation patterns indicate robust auditory nerve synchrony generated with octave-band chirps

Recent research has suggested that the amplitude of high-intensity compound action potentials (CAPs) can detect auditory nerve damage that is missed by traditional threshold measurements. The use of octave-band chirps may enhance neural synchrony and provide clinicians and researchers a precise tool for identifying changes in auditory nerve integrity. A group of Mongolian gerbils (N = 12) was used to compare the difference in amplitude-intensity functions and neural activation patterns generated by octave-band chirps and tonebursts at octave frequencies between 2 and 16 kHz at 40, 60, and 80 dB SPL. Amplitude-intensity functions revealed larger absolute CAP amplitudes for octave-band chirps than for tonebursts. Neural activation patterns were constructed by plotting the derivative of CAP amplitude across multiple conditions of simultaneous broadband noise that was high passed in 1/3 octave intervals. Neural activation patterns for octave-band chirps and tonebursts showed that the frequency location of peak activation was generally equivalent while the height of peak activation was greater for octave-band chirps than for tonebursts. This suggests that octave-band chirps elicit more synchronous neural firing, thereby indicating that they could be an optimal stimulus for detecting regional damage in auditory neurons that encode supra-threshold stimuli.

Relationships among measures of physical activity and hearing in African Americans: The Jackson Heart Study.

To evaluate the relationships among measures of physical activity and hearing in the Jackson Heart Study. Prospective cohort study. We assessed hearing on 1,221 Jackson Heart Study participants who also had validated physical activity questionnaire data on file. Hearing thresholds were measured across frequency octaves from 250 to 8,000 Hz, and various frequency pure-tone averages (PTAs) were constructed, including PTA4 (average of 500, 1,000, 2,000, and 4,000 Hz), PTA-high (average of 4,000 and 8,000 Hz), PTA-mid (average of 1,000 and 2,000 Hz), and PTA-low (average of 250 and 500 Hz). Hearing loss was defined for pure tones and pure-tone averages as >25 dB HL in either ear and averaged between the ears. Associations between physical activity and hearing were estimated using linear regression, reporting changes in decibel hearing level, and logistic regression, reporting odds ratios (OR) of hearing loss. Physical activity exhibited a statistically significant but small inverse relationship with PTA4, -0.20 dB HL per doubling of activity (95% confidence interval [CI]: -0.35, -0.04; P = .016), as well as with PTA-low and pure tones at 250, 2,000, and 4,000 Hz in adjusted models. Multivariable logistic regression modeling supported a decrease in the odds of high-frequency hearing loss among participants who reported at least some moderate weekly physical activity (PTA-high, OR: 0.69 [95% CI: 0.52, 0.92]; P = .011 and 4000 Hz, OR: 0.75 [95% CI: 0.57, 0.99]; P = .044). Our study provides further evidence that physical activity is related to better hearing; however, the clinical significance of this relationship cannot be estimated given the nature of the cross-sectional study design. 2b Laryngoscope, 126:2376-2381, 2016.

Uncertainties of reverberation time estimation via adaptively identified room impulse responses.

This paper investigates the reverberation time estimation methods which employ backward integration of adaptively identified room impulse responses (RIRs). Two kinds of conditions are considered; the first is the "ideal condition" where the anechoic and reverberant signals are both known a priori so that the RIRs can be identified using system identification methods. The second is that only the reverberant speech signal is available, and blind identification of the RIRs via dereverberation is employed for reverberation time estimation. Results show that under the "ideal condition," the average relative errors in 7 octave bands are less than 2% for white noise and 15% for speech, respectively, when both the anechoic and reverberant signals are available. In contrast, under the second condition, the average relative errors of the blindly identified RIR-based reverberation time estimation are around 20%-30% except the 63 Hz octave band. The fluctuation of reverberation times estimated under the second condition is more severe than that under the ideal condition and the relative error for low frequency octave bands is larger than that for high octave bands under both conditions.

Hearing loss and cognition in the Busselton Baby Boomer cohort: An epidemiological study.

To determine the relationship between peripheral hearing loss (HL) in baby boomers (better-ear measure) and cognitive function, taking into account the impact of depression or cognitive reserve on this relationship and exploring binaural hearing. A prospective, epidemiology study. Data from 1,969 participants aged 45 to 66 years were collected in the Busselton Healthy Ageing Study. Participants were assessed using pure-tone air-conduction thresholds at octave frequencies (250; 500; 1,000; 2,000; 4,000; and 8,000 Hz). Hearing loss was grouped using 1) pure-tone averages across 4 frequencies (500 to 4000Hz) in the better ear (BE4FA) or 2) latent profile analysis (LPA) using all thresholds from both ears. Cognition was tested with the Cognitive Drug Research System, verbal fluency, and National Adult Reading Test (premorbid-IQ). Regression was used to determine the impact of HL relative to no HL on age and education-adjusted cognition, controlling for mood, sex, and premorbid-IQ. According to BE4FA, 4.7% had mild (26-40 dB) HL; 0.8% had moderate (41-60 dB) HL; and 0.3% had severe (61-80 dB) HL. Based on the LPA, 20.5% had high-frequency HL; 7.8% had mid- to high-frequency HL; and 1.9% had significant HL across all frequencies. The HL group was not a predictor of cognitive performance in any domain using BE4FA and explained just 0.5% and 0.4% of variance in continuity-of-attention and speed-of-memory retrieval using LPA. Critically, those with the worst hearing did not differ cognitively from those with the best. Hearing loss is not an important determinant of contemporaneous attention, memory, or executive function in middle-aged adults once age, education, depression, cognitive reserve, and sex are controlled. 4. Laryngoscope, 126:2367-2375, 2016.

Analysis of Selected Methods Used For The Reverberation Time Estimation

Abstract The paper presents a comparison of the reverberation time of two boxed rooms considered in two variants. The purpose of the paper is the comparison of the reverberation time measurements results with the results obtained of the available equations and simulation in the ODEON software. The differences between the applicable models and computer simulation and measurement were analyzed. The determined values of the residual analysis were used to develop the rules for granting points to formulas or acoustic simulation. On this basis the choice of the best formula or acoustic simulation for a given octave frequency compared with the measured value was made.

Quantum frequency up-conversion of continuous variable entangled states

We demonstrate experimentally quantum frequency up-conversion of a continuous variable entangled optical field via sum-frequency-generation process. The two-color entangled state initially entangled at 806 and 1518 nm with an amplitude quadrature difference squeezing of 3.2 dB and phase quadrature sum squeezing of 3.1 dB is converted to a new entangled state at 530 and 1518 nm with the amplitude quadrature difference squeezing of 1.7 dB and phase quadrature sum squeezing of 1.8 dB. Our implementation enables the observation of entanglement between two light fields spanning approximately 1.5 octaves in optical frequency. The presented scheme is robust to the excess amplitude and phase noises of the pump field, making it a practical building block for quantum information processing and communication networks.

Wideband Tympanometry Normative Data for Turkish Young Adult Population.

The aim of this study was to obtain norm values for a young adult Turkish group and to investigate the differences between female and male subjects in terms of wideband tympanometry. One hundred ten young adult volunteers (mean±SD: 21.1±1.9 years) participated in this study. The measurements of wideband tympanometry were performed at octave frequencies between 226 Hz and 8000 Hz using Titan version 3.1. The stimulus level was set at 100 dB peSPL. A cross-sectional study design was used. In total, 218 ears were tested. A significant relationship was found between gender and absorbance values for the frequency band from 3100 Hz to 6900 Hz. The difference between the middle ear resonance frequency and ear canal volume (ECV) of the male and female subjects was also found to be significant. The difference in ECV may result from the difference in body size between the male and female subjects because there was a significant relationship among ECV and the height and weight. According to these results, it can be concluded that using separate norms for males and females may increase test specificity and sensitivity for the diagnosis of disorders, such as ossicular discontinuity and tympanic membrane perforations, affecting the high-frequency region.

Development and Validation of a Portable Hearing Self-Testing System Based on a Notebook Personal Computer.

Hearing loss affects more than 27 million people in mainland China. It would be helpful to develop a portable and self-testing audiometer for the timely detection of hearing loss so that the optimal clinical therapeutic schedule can be determined. The objective of this study was to develop a software-based hearing self-testing system. The software-based self-testing system consisted of a notebook computer, an external sound card, and a pair of 10-Ω insert earphones. The system could be used to test the hearing thresholds by individuals themselves in an interactive manner using software. The reliability and validity of the system at octave frequencies of 0.25 Hz to 8.0 kHz were analyzed in three series of experiments. Thirty-seven normal-hearing particpants (74 ears) were enrolled in experiment 1. Forty individuals (80 ears) with sensorineural hearing loss (SNHL) participated in experiment 2. Thirteen normal-hearing participants (26 ears) and 37 participants (74 ears) with SNHL were enrolled in experiment 3. Each participant was enrolled in only one of the three experiments. In all experiments, pure-tone audiometry in a sound insulation room (standard test) was regarded as the gold standard. SPSS for Windows, version 17.0, was used for statistical analysis. The paired t-test was used to compare the hearing thresholds between the standard test and software-based self-testing (self-test) in experiments 1 and 2. In experiment 3 (main study), one-way analysis of variance and post hoc comparisons were used to compare the hearing thresholds among the standard test and two rounds of the self-test. Linear correlation analysis was carried out for the self-tests performed twice. The concordance was analyzed between the standard test and the self-test using the kappa method. p < 0.05 was considered statistically significant. Experiments 1 and 2: The hearing thresholds determined by the two methods were not significantly different at frequencies of 250, 500, or 8000 Hz (p > 0.05) but were significantly different at frequencies of 1000, 2000, and 4000 Hz (p < 0.05), except for 1000 Hz in the right ear in experiment 2. Experiment 3: The hearing thresholds determined by the standard test and self-tests repeated twice were not significantly different at any frequency (p > 0.05). The overall sensitivity of the self-test method was 97.6%, and the specificity was 98.3%. The sensitivity was 97.6% and the specificity was 97% for the patients with SNHL. The self-test had significant concordance with the standard test (kappa value = 0.848, p < 0.001). This portable hearing self-testing system based on a notebook personal computer is a reliable and sensitive method for hearing threshold assessment and monitoring.

Geographic variation assessment of Bryde's whale (Balaenoptera edeni) Be4 call in the Gulf of California

Mysticeti whales modify their calls in response to an increase in noise level within their environment. This is particularly important since environmental noise has been increasing continuously in the last decades. In the case of Bryde's whale (Balaenoptera edeni), previous studies of its predominant call, Be4, have exposed differences in the duration of its main component (f0) for northern and southern areas of the Gulf of California (GC). The objective of this research is to determine if the differences found among Be4 calls (f0, duration, and energy distribution) are influenced by the noise levels in those areas. Results based on the characterization of Be4 Call and noise show that northern noise level is intense in the octave frequency band centered around 30 Hz, and could mask the 30 Hz component. This kind of noise is rare in the south (5%) and when it was present, the 30 Hz component was not registered, which might be an adaptation to noise. Predominant moderate noise in the south within the band 20 to 70 Hz overlaps the signals and higher components are present, especially the 165 Hz component. Results suggest that the difference between call from north and south areas might also be related to the noise present.

Stochastic micro-vibration response characteristics of a sandwich plate with MR visco-elastomer core and mass

The magneto-rheological visco-elastomer (MRVE) is used as a smart core to control the stochastic micro-vibration of a sandwich plate with supported mass. The micro-vibration response of the sandwich plate with MRVE core and supported mass under stochastic support motion excitations is studied and compared to evaluate the vibration suppression capability. The effects of the supported mass and localized magnetic field on the stochastic micro-vibration response of the MRVE sandwich plate are taken into account. The dynamic characteristics of the MRVE core in micro-vibration are described by a non-homogeneous complex modulus dependent on vibration frequency and controllable by applied magnetic fields. The partial differential equations for the coupled transverse and longitudinal motions of the MRVE sandwich plate with supported mass are derived from the dynamic equilibrium, constitutive and geometric relations. The simplified ordinary differential equations are obtained for the transverse vibration of the MRVE sandwich plate under localized magnetic fields. A frequency-domain solution method for the stochastic micro-vibration response of sandwich plates with supported mass is developed based on the Galerkin method and random vibration theory. The expressions of frequency-response functions, response power spectral densities and root-mean-square velocity responses of the plate in terms of the one-third octave frequency band are obtained for micro-vibration evaluation. Finally, numerical results are given to illustrate the large response reduction capacity of the MRVE sandwich plate with supported mass under stochastic support motion excitations, and the influences of MRVE parameters, supported mass and localized magnetic field placement on the micro-vibration response.

Applications of the NTID speech recognition test (NSRT®)

Objective: This study evaluated the diagnostic capabilities of an adaptive speech recognition protocol (NSRT®) that can be self-administered in non-clinical venues by listeners using internet-based software. Design: All participants were given an audiological evaluation, including pure-tone testing, and responded to the NSRT administered in quiet and + 5 dB SNR listening conditions. The NSRT test materials are sentence-length utterances containing phonetic contrasts, primarily minimal pairs. Study sample: Subjects were 123 adults with normal hearing to moderately severe sensorineural hearing loss (mean age = 55 years, SD = 23). Results: Performance on the NSRT is strongly related to pure-tone thresholds. Linear regression analyses support the utility of the NSRT as a proxy for clinically-obtained hearing thresholds across the octave frequencies 0.5 to 8 kHz, primarily for individuals in the − 10 to 55 dB HL range. Other NSRT results are linked to analyses of phonetic errors and components of aural rehabilitation. Conclusions: Among its numerous results, the NSRT yields quantitative predictions of frequency-specific hearing thresholds, provides insight into the phonetic errors that affect speech understanding in adults who suffer from sensorineural hearing loss, primarily in the − 10 to 55 dB HL range, and has implications for the design of individualized auditory training programs.