Octave Frequency Research Articles

Line Intensity Mapping with [C ii] and CO(1-0) as Probes of Primordial Non-Gaussianity

Constraints on primordial non-Gaussianity (PNG) will shed light on the origin of primordial fluctuations and the physics of the early universe. The intensity mapping technique is a promising probe of structure formation on large scales; at high redshifts, it can provide complementary information to other cosmological probes. We explore the potential of future wide-field [CII] and CO intensity mapping surveys in constraining PNG of the local shape, which induces a distinct, scale-dependent correction to the line bias. We explore the parameter space of CO and [CII] survey designs that can achieve the nominal target of $\sigma(f_{\rm NL}^{\rm loc}) =1$ and further calculate what constraints such surveys can place on PNG of the equilateral, orthogonal, and quasi-single field shapes. We further test the dependence of these constraints on various model assumptions; namely the halo mass function, modeling of line bias, and correlation between mass and [CII]/CO luminosity. We find that the ability of CO and [CII] intensity mapping surveys to constrain $f_{\rm NL}^{\rm loc}$ relies heavily on the spectral (redshift) coverage, requiring at least a coverage of an octave in frequency, to produce significant results, with the optimized surveys generally covering between $z\sim[2-8]$. As this redshift window partially overlaps with 21-cm EoR experiments like the Hydrogen Epoch of Reionization Array (HERA), we additionally explore the prospects for a hypothetical set of surveys to place constraints on $\sigma(f_{\rm NL}^{\rm loc})$ utilizing multi-tracer analysis between the lines of HI, CO, and [CII].

Evaluating hospital soundscapes to improve patient experience.

Hospital soundscapes can be difficult environments to assess acoustically due to alarms, medical equipment, and the continuous activity within units. Routinely, patients perceive these soundscapes to be poor when rating their hospital experience on HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) surveys administered after discharge. In this study, five hospital units of widely varying HCAHPS "quietness" performance were analyzed. Sound pressure levels were measured in 15 patient rooms and 5 nursing stations over 24-h periods. HCAHPS "quietness of the hospital environment" patient survey data were correlated with measured acoustical data at a room-level, revealing acoustical metrics linked to patient perceptions of hospital soundscape conditions. Metrics found to be statistically correlated (p < 0.05) included the absolute LAMIN levels in patient rooms, which found significantly higher HCAHPS quietness scores in units with average LAMIN levels below 35 dBA, in addition to specific low frequency octave bands and occurrence rates. Many other standard acoustical metrics (such as LAEQ, LAMAX, LCPEAK, and LA90) were not found to be statistically correlated between measured acoustical data and HCAHPS quietness patient responses. Taken as a whole, this study provides insights into the potential relationships between hospital noise and patient satisfaction.

Comparison of hearing thresholds using audiometric versus android-based application

Background: Hearing loss is a highly widespread problem worldwide and early identification of hearing loss through screening is important to overcome the negative effects of untreated hearing impairment. Screening can be done using handheld device app technologies for the hearing assessments that would be easy to be used by any individual. Aims and Objectives: The aim of the present study was to compare the hearing thresholds with smartphone application and conventional audiometer. Materials and Methods: A total of 52 participants were included in the study. They were divided into two groups. Group 1 included 36 participants (72 ears) in the age range of 7 to 35 years with normal hearing sensitivity. Group 2 included 16 participants (32 ears) in the age range of 18-68 years with varying degree of hearing loss ranging from minimal hearing loss to severe hearing loss. Thus, a total of 104 ears were tested. Air Conduction thresholds were obtained at octave frequencies from 250 Hz to 4000 Hz using conventional audiometer in a sound treated room and through the android application (Hearing test version 1.1.) using a smart phone (Micromax Xpress Canvas) in a quiet room. The noise levels for hearing assessment through smart phone app ranged between 70-75 dB A, which was measured prior to the testing session. The thresholds were obtained for both right and left ear of the participants. The hearing thresholds obtained from both the measures was subjected to appropriate statistical analysis. Results: The results showed that there was a significant difference in the thresholds across the procedures for all the frequencies in Group 1. However, there was no significant difference in thresholds across the procedures for all the frequencies in Group 2. Conclusion: It can be concluded that hearing screening through mobile application is user-friendly and cost-effective, but it might lead into under referrals.

Development of a Time-Efficient Approach to Measure the Acoustic Impedance of Industrial Insulating Materials

This study presents a development on a time efficient approach to measure the Acoustic Impedance of Industrial Insulating materials using an impedance tube with single moveable microphone and a white noise generator. The standing wave method is used to measure the acoustic properties (absorption coefficient and acoustic impedance) of sound absorbing materials. In order to use a burst of white noise instead of individual stationary sine waves, a signal processing technique was developed. The algorithm is based on the equation of simple harmonic motion, but uses distance as a variable, instead of time. This innovative method allows measuring at frequency resolutions as low as 5 Hz in a reasonably short amount of time. This is an advantage, as the classical standing wave method uses frequency resolutions of one-third of octaves for measurements, as otherwise time would be prohibitive. Experimental results are validated with those measured with the sine wave generator using one-third of octave frequencies by comparing their behaviours.

A Large-Scale Examination of Veterans with Normal Pure-Tone Hearing Thresholds within the Department of Veterans Affairs

Department of Veterans Affairs (VA) audiologists have anecdotally reported examining numerous Veterans with normal pure-tone thresholds; however, the prevalence of these patients within the VA is unknown. The VA audiological data repository provides an ideal dataset to examine this group of Veterans. Knowing the prevalence of normal-hearing Veterans within the VA system is the first step to understanding the underlying referral patterns and clinical complaints of Veterans. Data repositories which capture data from both normal and impaired populations provide an indispensable view into hearing health care which can help to improve diagnosis and treatment of Veterans' hearing difficulties. Using the VA audiological data repository, this study aimed to (1) determine the prevalence of normal hearing thresholds among Veterans seeking hearing health care within the VA health care system and (2) determine the prevalence of abnormal clinical audiology test results among Veterans with normal hearing thresholds. This study was a large-scale retrospective, descriptive observational analysis of uploaded audiological records from the VA Denver Acquisition and Logistics Center audiological data repository encompassing visits that took place between April 1991 and June 2015. At the time of data extraction, there were 3,641,326 audiological records in the repository, with 2,322,771 unique individual records. The study sample was further restricted to include only individuals with normal hearing (n = 235,091), which was defined as pure-tone thresholds better than, or equal to, 25 dB HL at octave frequencies from 250 to 8000 Hz, bilaterally. Patients ranged from 19 to 90+ years of age. We describe the data using frequencies and percentages for categorical variables and means and standard deviations for continuous variables. In addition to hearing thresholds, the occurrence of abnormal results on other tests in the audiological test battery is also reported. We estimate the prevalence of normal hearing among all Veterans with records in the VA audiological data repository. Veterans with normal hearing were on average 37 yr old. The prevalence of Veterans with normal hearing thresholds visiting VA audiology clinics in the current hearing repository dataset was 10.12%. Overall, 41% of Veterans with normal pure-tone thresholds had other clinically abnormal audiological test results; for example, contralateral acoustic reflex thresholds (31.7%) and tympanometry (21.5%) had the highest rate of abnormal test results. Approximately one in ten Veterans seeking care within the VA healthcare system, and reported to the VA audiological data repository, has normal pure-tone hearing thresholds. This may be an underestimate of the true underlying prevalence of normal-hearing Veterans seeking audiology services at the VA because records with normal results were not consistently submitted to the repository. In addition, 41% of Veterans with normal pure-tone thresholds nonetheless presented with other audiological abnormalities. This study suggests that future work directed toward understanding referral patterns and clinical complaints of individuals who present to VA audiology clinics with normal hearing thresholds may be fruitful in the cause of improving diagnosis and treatment of Veterans' hearing difficulties.

Patients With Normal Hearing Thresholds but Difficulty Hearing in Noisy Environments: A Study on the Willingness to Try Auditory Training.

Persons with normal audiometric thresholds but excessive difficulty hearing in background noise will choose auditory training as a treatment option. Auditory training has traditionally been reserved for those with marked hearing loss. We investigated auditory training as a treatment option for those who have normal auditory thresholds but complain about hearing in noise-a population of patients for which no therapy or intervention currently exists. We also determined the willingness of this patient population to volunteer for a free auditory training program. We administered a 14-item, telephone-based questionnaire to assess perceived difficulty hearing in noise and willingness to volunteer for auditory training. We developed questions to identify those who consistently reported difficulty hearing in noise, but not quiet. The 11,938-person database included 2,299 patients with pure-tone averages less than 25. A total of 474 of these patients completed our questionnaire, 135 of who had normal audiometric thresholds at all octave frequencies 0.25 to 8 kHz. We found that difficulty hearing in noise was a graded problem. Our approach to find consistent reports about hearing in noise showed that the majority of people who consistently had difficulty hearing in noise, but not quiet, were the most likely to try auditory training. While relatively few patients with both normal hearing thresholds and complaints of severe difficulty hearing in noise were in the database, these patients were generally willing to volunteer for auditory training. Our results provide evidence that many in this underserved population would volunteer for auditory training.

Wideband transient otoacoustic emissions in ears with normal hearing and sensorineural hearing loss

Otoacoustic emissions (OAEs) are generated in the cochlea in response to sound and are used clinically to separate ears with normal hearing from sensorineural hearing loss (SNHL). OAEs were elicited at ambient pressure by clicks (CEOAE) and wideband chirps (TEOAE) sweeping from low-to-high frequency with a sweep rate of either 187.6 Hz/ms (short chirps) or 58.2 Hz/ms (long chirps) and a bandwidth extending to 8 kHz. Chirps were presented at the same sound exposure level (SEL) as clicks, or + 6 dB relative to clicks. A total of 288 OAE waveforms were averaged for short chirps in ~1 minute compared to 120 waveforms for long chirps. Compared to clicks, the chirp has a lower crest factor, which allows it to be presented at an overall higher SEL without distortion. OAEs were elicited in 79 adults with normal hearing and 51 adults with mild-to-moderate SNHL. One-sixth octave OAE signal-to-noise ratios from 0.7 to 8.0 kHz were compared across stimulus types and conditions. The area under the receiver operating curve (AUC) was used to assess the accuracy of detecting SNHL. Average AUCs across 1/6th octave frequencies ranged from 0.90 to 0.89 for TEOAEs and were 0.87 for the CEOAE suggesting excellent test performance.

RETRACTED: K-means clustering analysis and evaluation for internet of acoustic environment characteristics

Abstract In order to improve the validity of acoustic environment characteristic analysis of university libraries, an evaluation study method of acoustic environment characteristic cluster analysis of university libraries was proposed based on the modified Cop-Kmeans algorithm scheme. Firstly, Fraunhofer theory was used for establishing the sound diffusion proper quantification method of Schroeder diffusion to obtain diffusion coefficient with 1/3 octave frequency band, as well as adopting normalized method to eliminate the edge diffraction scattering effect produced under the extreme dimensions. Secondly, against adverse effect that the personal property of pairing constraint might have on the precision of cluster results, the paper improved the algorithm further based on the first solution. Two distribution rules were formulated respectively to find out sample sets with direct or indirect constrained relationship and distribute some or multiple samples with highest accuracy of distribution in priority, which enhanced the cluster quality to some extent. At last, the validity of the proposed algorithm was verified through simulation experiments.

Comparison of the Minimum Plateau Width by Plateau and a New Method in People with Conductive Hearing Loss.

Background and ObjectivesIn clinical masking, the plateau is a state in which the non-test ear (NTE) is completely masked by the noise and tone is heard only by the test ear (TE). At least 15 to 20 dB of plateau width is needed to obtain valid threshold. In the study, a part of plateau after initial masking level known as the minimum plateau width (mPW) was determined and compared by a new formula and the plateau searching method. Subjects and MethodsMinimum plateau widths of air conduction were obtained in 29 participants with unilateral and 30 participants with bilateral conductive hearing loss (CHL) aged 20 to 45 years old by using step by step plateau method and mPW estimation by the formula between two points of masking diagram [mPW=(N2-N1)-(T2-T1)] and then the mPW of two methods was compared for each frequency. ResultsThere was no significant difference between the minimum plateau width obtained by the plateau and formula methods for two given point of masking diagram in people with unilateral and bilateral CHL at octave frequencies from 500 Hz to 4,000 Hz. ConclusionsThreshold obtaining of TE by two tones for two noise levels delivered to the NTE is enough to estimate the mPW between these two noise points and it is not necessary that for clinicians to know the actual values of masking diagram components.

Hearing Loss in Children With Otitis Media With Effusion: Actual and Simulated Effects on Speech Perception.

Conductive hearing loss simulations have attempted to estimate the speech-understanding difficulties of children with otitis media with effusion (OME). However, the validity of this approach has not been evaluated. The research aim of the present study was to investigate whether a simple, frequency-specific, attenuation-based simulation of OME-related hearing loss was able to reflect the actual effects of conductive hearing loss on speech perception. Forty-one school-age children with OME-related hearing loss were recruited. Each child with OME was matched with a same sex and age counterpart with normal hearing to make a participant pair. Pure-tone threshold differences at octave frequencies from 125 to 8000 Hz for every participant pair were used as the simulation attenuation levels for the normal-hearing children. Another group of 41 school-age otologically normal children were recruited as a control group without actual or simulated hearing loss. The Mandarin Hearing in Noise Test was utilized, and sentence recall accuracy at four signal to noise ratios (SNR) considered representative of classroom-listening conditions were derived, as well as reception thresholds for sentences (RTS) in quiet and in noise using adaptive protocols. The speech perception in quiet and in noise of children with simulated OME-related hearing loss was significantly poorer than that of otologically normal children. Analysis showed that RTS in quiet of children with OME-related hearing loss and of children with simulated OME-related hearing loss was significantly correlated and comparable. A repeated-measures analysis suggested that sentence recall accuracy obtained at 5-dB SNR, 0-dB SNR, and -5-dB SNR was similar between children with actual and simulated OME-related hearing loss. However, RTS in noise in children with OME was significantly better than that for children with simulated OME-related hearing loss. The present frequency-specific, attenuation-based simulation method reflected the effects of OME-related hearing loss on speech perception impairment in quiet environments. In noisy environments, the simulation method could only approximately estimate the effects of OME-related hearing loss on speech perception in typical classroom noise levels. Children with OME-related hearing loss may develop compensatory strategies to reduce the effects of hearing loss in adverse listening environments.

Temporal Fine Structure Processing, Pitch, and Speech Perception in Adult Cochlear Implant Recipients.

The aim of the study was to investigate the link between temporal fine structure (TFS) processing, pitch, and speech perception performance in adult cochlear implant (CI) recipients, including bimodal listeners who may benefit better low-frequency (LF) temporal coding in the contralateral ear. The study participants were 43 adult CI recipients (23 unilateral, 6 bilateral, and 14 bimodal listeners). Two new LF pitch perception tests-harmonic intonation (HI) and disharmonic intonation (DI)-were used to evaluate TFS sensitivity. HI and DI were designed to estimate a difference limen for discrimination of tone changes based on harmonic or inharmonic pitch glides. Speech perception was assessed using the newly developed Italian Sentence Test with Adaptive Randomized Roving level (STARR) test where sentences relevant to everyday contexts were presented at low, medium, and high levels in a fluctuating background noise to estimate a speech reception threshold (SRT). Although TFS and STARR performances in the majority of CI recipients were much poorer than those of hearing people reported in the literature, a considerable intersubject variability was observed. For CI listeners, median just noticeable differences were 27.0 and 147.0 Hz for HI and DI, respectively. HI outcomes were significantly better than those for DI. Median STARR score was 14.8 dB. Better performers with speech reception thresholds less than 20 dB had a median score of 8.6 dB. A significant effect of age was observed for both HI/DI tests, suggesting that TFS sensitivity tended to worsen with increasing age. CI pure-tone thresholds and duration of profound deafness were significantly correlated with STARR performance. Bimodal users showed significantly better TFS and STARR performance for bimodal listening than for their CI-only condition. Median bimodal gains were 33.0 Hz for the HI test and 95.0 Hz for the DI test. DI outcomes in bimodal users revealed a significant correlation with unaided hearing thresholds for octave frequencies lower than 1000 Hz. Median STARR scores were 17.3 versus 8.1 dB for CI only and bimodal listening, respectively. STARR performance was significantly correlated with HI findings for CI listeners and with those of DI for bimodal listeners. LF pitch perception was found to be abnormal in the majority of adult CI recipients, confirming poor TFS processing of CIs. Similarly, the STARR findings reflected a common performance deterioration with the HI/DI tests, suggesting the cause probably being a lack of access to TFS information. Contralateral hearing aid users obtained a remarkable bimodal benefit for all tests. Such results highlighted the importance of TFS cues for challenging speech perception and the relevance to everyday listening conditions. HI/DI and STARR tests show promise for gaining insights into how TFS and speech perception are being limited and may guide the customization of CI program parameters and support the fine tuning of bimodal listening.

Development of Improved Software Intelligent System for Audiological Solutions.

Of late, there has been an increase in hearing impairment cases and to provide the most advantageous solutions to them is an uphill task for audiologists. Significant difficulty faced by the audiologists is in effective programming of hearing aids to provide enhanced satisfaction to the users. The main aim of our study was to develop a software intelligent system (SIS): (i) to perform the required audiological investigations for finding the degree and type of hearing loss, and (ii) to suggest appropriate values of hearing aid parameters for enhancing the speech intelligibility and the satisfaction level among the hearing aid users. In this paper, we present a Neuro-Fuzzy based SIS to automatically predict and suggest the hearing-aid parameters such as gain values, compression ratio and threshold knee point, which are needed to be fixed for different octave frequencies of sound inputs during the hearing-aid trial. The test signals for audiological investigations are generated through the standard hardware present in a personal computer system and with the aid of a software algorithm. The proposed system was validated with 243 subjects' data collected at the Government General Hospital, Chennai, India. The calculated sensitivity, specificity and accuracy of the proposed audiometer incorporated in the SIS were 98.6%, 96.4 and 98.2%, respectively, by comparing its interpretations with those of the 'gold standard' audiometers. Furthermore, 91% (221 of 243) of the hearing impaired subjects attained satisfaction in the first hearing aid trials itself with the gain values as recommended by the improved SIS. The proposed system reduced around 75% of the 'trial and error' time spent by audiologists for enhancing satisfactory usage of the hearing aid. Hence, the proposed SIS could be used to find the degree and type of hearing loss and to recommend hearing aid parameters to provide optimal solutions to the hearing aid users.

Tone-Evoked Acoustic Change Complex (ACC) Recorded in a Sedated Animal Model.

The acoustic change complex (ACC) is a scalp-recorded cortical evoked potential complex generated in response to changes (e.g., frequency, amplitude) in an auditory stimulus. The ACC has been well studied in humans, but to our knowledge, no animal model has been evaluated. In particular, it was not known whether the ACC could be recorded under the conditions of sedation that likely would be necessary for recordings from animals. For that reason, we tested the feasibility of recording ACC from sedated cats in response to changes of frequency and amplitude of pure-tone stimuli. Cats were sedated with ketamine and acepromazine, and subdermal needle electrodes were used to record electroencephalographic (EEG) activity. Tones were presented from a small loudspeaker located near the right ear. Continuous tones alternated at 500-ms intervals between two frequencies or two levels. Neurometric functions were created by recording neural response amplitudes while systematically varying the magnitude of steps in frequency centered in octave frequency around 2, 4, 8, and 16kHz, all at 75dB SPL, or in decibel level around 75dB SPL tested at 4 and 8kHz. The ACC could be recorded readily under this ketamine/azepromazine sedation. In contrast, ACC could not be recorded reliably under any level of isoflurane anesthesia that was tested. The minimum frequency (expressed as Weber fractions (df/f)) or level steps (expressed indB) needed to elicit ACC fell in the range of previous thresholds reported in animal psychophysical tests of discrimination. The success in recording ACC in sedated animals suggests that the ACC will be a useful tool for evaluation of other aspects of auditory acuity in normal hearing and, presumably, in electrical cochlear stimulation, especially for novel stimulation modes that are not yet feasible in humans.

Isotropic Effective Spin-Orbit Coupling in a Conjugated Polymer.

Conjugated polymers are anisotropic in shape and with regard to electronic properties. Little is known as to how electronic anisotropy impacts the underlying characteristics of the electron spin, such as the coupling to orbital magnetic moments. Using multifrequency electrically detected magnetic resonance spectroscopy extending over 12 octaves in frequency, we explore the effect of spin-orbit coupling by examining the pronounced broadening of resonance spectra with increasing magnetic field. Whereas in three commonly used materials, the high-field spectra show asymmetric broadening, as would be expected from anisotropic g-strain effects associated with the molecular structure, in the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) the spectra broaden isotropically, providing a direct measure of the microscopic distribution in g-factors. This observation implies that effective charge-carrier g-tensors are isotropic, which likely originates from motional narrowing in this high-mobility material.

Wideband high-efficient linear polarization rotators

We demonstrate a wideband polarization rotator with characteristics of high efficiency and large-range incidence angle by using a very simple anisotropic reflective metasurface. The calculated results show that reflection coefficient of cross polarization is larger than 71% over an octave frequency bandwidth from ~4.9 GHz to ~10.4 GHz. The proposed metasurface can still work very well even at incidence angle of 60°. The experiment at microwave frequencies is carried out and its results agree well with the simulated ones.

Protective earphones and human hearing system response to the received sound frequency signals

Sound is one of the most important problems in industrial environments, and it causes hearing loss at different frequencies in the workforce. Incorrect fitting of hearing protector has a negative effect on noise reduction. The present study was conducted with the aim of determination of the effective frequencies on hearing loss and variations of the sound level in different frequencies after placing the earplug. A model of ear canal with different materials was simulated. Sound pressure sensors and earplugs were placed in both sides of the ear canal. The rates of sound reduction in octave frequency signals were calculated for the simulated canal of different materials, in different distances between the microphone and the earplug with Labview software. The results of sound simulation in octave frequency signals showed that by increasing the frequency, the rates of sound reduction in different conditions also had an increasing trend. The obtained peak rates for all the situations coincided with each other at fixed frequencies. In most cases, a noise reduction in the frequency of 4000 Hz showed a high number. The maximum sound reduction was observed at 25.5 mm at frequencies below 250 Hz, which was similar to the average of human ear canal length; so the simulated model can be used to determine the performance of the protective earphones and test them at different frequencies and sound pressure levels.

A review of single crystal underwater transducers

The unique material properties of lead magnesium niobate-lead titanate (PMN-PT) single crystals enable compact, broadband, high power sound projectors that cannot be realized using conventional ceramics. This paper shall highlight single crystal transducer prototypes developed at the Naval Undersea Warfare Center, Division Newport, and elsewhere demonstrating that the broadband, high power performance promised by single crystal’s material properties can be realized in practical underwater transducers. Various single crystal transducer designs for underwater applications, including longitudinal vibrators, fully active and active-passive air-backed cylinder transducers, free-flooded ring transducers and bender bar transducers, will be shown. These transducer designs cover a wide span of frequencies, and utilize both 33- and 32- operating modes. Tuned bandwidths of up to 2.5 octaves of frequency, as well as source level increases of up to 15 dB at the band edges, will be demonstrated. t will also be shown that these technologies provide stable performance under high drive and duty cycle conditions. Finally, the impact of using these single crystal sources on the drive electronics and power consumption shall also be discussed.

Improving acquisition time of the frequency-specific auditory brainstem response through simultaneous independently random toneburst sequences

The frequency-specific auditory brainstem response (ABR) is an objective electroencephalographic (EEG) method for estimating auditory thresholds when behavioral thresholds are not attainable, primarily in infants and toddlers. It is recorded by repeatedly presenting brief, band-limited tonebursts and averaging the scalp potential response. In a typical ABR evaluation, measurements are made at multiple intensities, at multiple frequencies, and in both ears, leading to a large combinatorial space and long test times. Here, we present a method of recording the responses at five frequencies in both ears simultaneously, along with preliminary data demonstrating its effectiveness. We created ten toneburst trains—five octave frequencies (500–8000 Hz) by two ears—for simultaneous presentation. Importantly, the toneburst timing for each train was dictated by an independent random process, rather than being periodic. Independent sequences allow separate computation of the ABR to each of the toneburst trains as the cross-correlation of its timing sequence and the EEG recording. Early results suggest substantial improvements in recording time, particularly at lower stimulus intensities. It also appears that cochlear spread of excitation—a problem at high intensities—is mitigated by our method. This improvement in place specificity is predicted by modeling of auditory nerve activity.

The relation between choir size and choir dynamics

If six distinct levels of choir dynamics ( pp p mp mf f ff ) are to be achieved over two octaves of fundamental frequency in a choir section, how distinct are these levels? The just noticeable difference for sound level in a free field environment is 1-2 dB, while a doubling of loudness requires a 10 phon increase (10 dB SL increase at 1000 Hz). Most singers cannot double their vocal loudness 5 times. Generally the dynamic levels are 3–6 dB apart, depending on the individual voice range profiles of the singers. Overall choir size has no effect on dynamic range, unless the size is varied dynamically by not all singers singing all the time. A few loud voices dominate ff if everyone sings. To achieve an effective choir pp, only a few voices who can sustain very soft notes should sing. The dynamic range can be significantly limited when choral blend for loudness is imposed on a non-homogeneous group of singers.

Gliding ripple speed thresholds for rippled spectra

Rippled noise is a productive model of natural signals with complex spectrum patterns. It was used as a test signal to measure spectrum-pattern resolution both in normal-hearing listeners and in hearing-impaired listeners and users of cochlear implants. However, a variety of natural auditory signals feature combined spectro-temporal patterns. These signals may be modeled by rippled noise with ripples. In the present study, ripple gliding speed thresholds were measured in normal-hearing listeners. The highest gliding speed (expressed in oct/s or ripples/s) at which the gliding ripple pattern could be distinguished from a non-rippled noise was determined. The ripple gliding speed threshold expressed in ripple/s was inversely-proportional to the ripple density (ripples per octave, RPO); it decreased from approximately 400–500 ripple/s at RPO of 1/oct to approximately 50 ripple/s at RPO of 10/oct. Expressed in oct/s, the threshold decreased from 400 to 500 oct/s at RPO of 1/oct to 5 oct/s at RPO of 10/oct. Thus, the ripples fused into non-rippled spectrum at gliding speed more than 400 to 500 Hz/oct. At this speed, 400 to 500 ripples per second glide through an octave frequency band. [Work supported by The Russian Science Foundation, Grant 16-15-10046.]Rippled noise is a productive model of natural signals with complex spectrum patterns. It was used as a test signal to measure spectrum-pattern resolution both in normal-hearing listeners and in hearing-impaired listeners and users of cochlear implants. However, a variety of natural auditory signals feature combined spectro-temporal patterns. These signals may be modeled by rippled noise with ripples. In the present study, ripple gliding speed thresholds were measured in normal-hearing listeners. The highest gliding speed (expressed in oct/s or ripples/s) at which the gliding ripple pattern could be distinguished from a non-rippled noise was determined. The ripple gliding speed threshold expressed in ripple/s was inversely-proportional to the ripple density (ripples per octave, RPO); it decreased from approximately 400–500 ripple/s at RPO of 1/oct to approximately 50 ripple/s at RPO of 10/oct. Expressed in oct/s, the threshold decreased from 400 to 500 oct/s at RPO of 1/oct to 5 oct/s at RPO of ...