Loudness Measurements Research Articles

"Measurement" of Tinnitus.

Chronic tinnitus is the persistent sensation of hearing a sound that exists only inside the head. The prevalence of tinnitus in adults in the United States is estimated at 10 to 15%. For about 20% of these individuals the tinnitus is significantly bothersome. Although myriad therapies for tinnitus are offered (often at significant cost), most are not evidence based. Difficulty in the assessment and further development of interventions for tinnitus stems from the limitations of techniques used to evaluate these interventions. Questionnaires are widely available to "measure" (tinnitus can only be indirectly measured) functional effects of tinnitus, such as difficulty sleeping and concentrating, and negative emotions such as anxiety, depression, and annoyance. Questionnaires have recently been documented for sensitivity to change in response to intervention (i.e., "responsiveness"). All of these questionnaires function well to assess the overall impact of tinnitus. The limitations mentioned pertain primarily to measures of tinnitus perception, which typically include the psychoacoustic measures of tinnitus loudness and pitch matches, tinnitus spectral content, minimum masking levels, and residual inhibition. These measures, which are obtained routinely in many clinics and as part of research studies, have not been validated for being diagnostic, prognostic, discriminative, or responsive. In order for these measures to become clinically meaningful, normative standards are needed, both for baseline measures and for repeated measures of tinnitus perception. Evidence-based intervention for tinnitus requires accurately measuring both the perception of, and reactions to, tinnitus.

Effects of Expiratory Muscle Strength Training on Lung Function and Musical Performance in Collegiate Wind Instrumentalists

Expiratory muscle strength training (EMST) has been associated with increased maximum expiratory pressure (MEP). Because wind instrumentalists depend on sufficient pressure production for optimal musical performance, it is possible that EMST might improve musical performance in this population. The purpose of this study was to determine if 4 weeks of EMST would improve instrumental performance in relation to MEP in college-level wind instrumentalists. All participants (N=19) were pre-tested for MEP (inH 2 O) and musical performance measures of loudness (dB) and duration of play (sec) on various pitches. Participants were then divided into groups matched by MEP, gender, and instrument. The experimental group (n=12) trained 4 times/week for 4 weeks at 75% MEP. Following training, MEP increased significantly in the experimental group (pre: 49.50±14.41; post: 83.17±22.47 inH 2 O) compared to the control group (pre: 50.29±7.76; post: 53.14±11.89 inH 2 O, p< 0.0001). There were no significant musical performance improvements as measured following training, but results suggest that EMST may be a viable option for instrumental training. Future research might build upon this study design to better assess the effects of EMST on musical performance in wind instrumentalists by considering alternate definitions for musical performance and by assessing specific instruments separately.

Using Reaction Time and Equal Latency Contours to Derive Auditory Weighting Functions in Sea Lions and Dolphins.

Subjective loudness measurements are used to create equal-loudness contours and auditory weighting functions for human noise-mitigation criteria; however, comparable direct measurements of subjective loudness with animal subjects are difficult to conduct. In this study, simple reaction time to pure tones was measured as a proxy for subjective loudness in a Tursiops truncatus and Zalophus californianus. Contours fit to equal reaction-time curves were then used to estimate the shapes of auditory weighting functions.

Modeling the Individual Variability of Loudness Perception with a Multi-Category Psychometric Function.

Loudness is a suprathreshold percept that provides insight into the status of the entire auditory pathway. Individuals with matched thresholds can show individual variability in their loudness perception that is currently not well understood. As a means to analyze and model listener variability, we introduce the multi-category psychometric function (MCPF), a novel representation for categorical data that fully describes the probabilistic relationship between stimulus level and categorical-loudness perception. We present results based on categorical loudness scaling (CLS) data for adults with normal-hearing (NH) and hearing loss (HL). We show how the MCPF can be used to improve CLS estimates, by combining listener models with maximum-likelihood (ML) estimation. We also describe how the MCPF could be used in an entropy-based stimulus-selection technique. These techniques utilize the probabilistic nature of categorical perception, a novel usage of this dimension of loudness information, to improve the quality of loudness measurements.

An Acoustic-Phonetic Model of F0 Likelihood for Vocal Melody Extraction

This paper presents a novel approach to extraction of vocal melodies from accompanied singing recordings. Central to our approach is a model of vocal fundamental frequency (F0) likelihood that integrates acoustic-phonetic knowledge and real-world data. This model consists of a timbral fitness score and a loudness measure of each F0 candidate. Timbral fitness is measured for the partial amplitudes of an F0 candidate, with respect to a small set of vocal timbre examples. This F0-specific measurement of timbral fitness depends on an acoustic-phonetic F0 modification of each timbre example. In the loudness part of the likelihood model, sinusoids are detected, tracked, and pruned to give loudness values that minimize interference from the accompaniment. A final F0 estimate is determined by a prior model of F0 sequence in addition to the likelihood model. Melody extraction is completed by detecting voiced time positions according to the singing voice loudness variations given by the estimated F0 sequence. The numerical parameters involved in our approach were optimized on three development sets from different sources before the system was evaluated on ten test sets separate from these development sets. Controlled experiments show that use of the timbral fitness score accounts for a 13% difference in overall accuracy.

Some factors affecting loudness measurement and prediction

The current ANSI standard (ANSI S3.4, 2007) estimates the loudness of sustained sound, but many naturally occurring sounds have time-varying levels. Glasberg and Moore (2002) published a model for the prediction of time-varying sounds and this aspect should be considered as part of a revision to the ANSI standard. To assess the predictions of the dynamic model, loudness magnitude estimation functions were obtained for 24 listeners using pure tones (0.5 and 1.0 kHz), vowels, spondees, and speech-shaped noise (SSN) presented at levels from 40 to 90 dB SPL. Inferred equal-loudness levels from the fitted loudness functions were compared to the model predictions. The loudness model was qualitatively consistent with the behavioral data. The model predicted SSN to be louder than vowels and spondees which would be louder than tones; however, the model over-predicted the loudness differences. Possible explanations for the over-prediction include biases in loudness judgments, cognitive factors regarding learned expectations for loudness, assumptions regarding the free-field-to-headphone transfer function, and the model’s over-prediction of spectral, loudness summation, a result found recently (Schlittenlacher et al., 2014) for the ANSI standard and DIN 45631.

Clinical trials supported by the Tinnitus Research Consortium: Lessons learned, the Southern Illinois University experience

The Tinnitus Research Consortium funded three clinical trials investigating treatments for chronic bothersome tinnitus at Southern Illinois University School of Medicine. The trials were designed to measure the subjective changes in tinnitus distress using standardized questionnaires and objective changes in tinnitus loudness using psychophysical matching procedures. The results of the first two trials have been published and are summarized here. The first trial investigated the effect of gabapentin on the loudness and annoyance of tinnitus in adults with chronic bothersome tinnitus with and without a history of acoustic trauma. A small but significant number of subjects reported decreased tinnitus annoyance that corresponded with a decrease in objective measures of tinnitus loudness during active drug treatment with a washout effect during placebo treatment. The second trial compared the effect of tinnitus retraining therapy (TRT) on adults with normal to near-normal hearing and chronic bothersome tinnitus to treatment with general counseling without acoustic enrichment. Significant improvements in tinnitus severity, but not in objective psychometric measures of tinnitus loudness, occurred in both treatment groups, however a greater effect was observed in the TRT group compared with the control group. The third trial is nearing completion and investigates the long-term results of tinnitus retraining therapy on chronic bothersome tinnitus in adults with hearing loss. Significant lessons and observations on conducting tinnitus clinical trials were learned from these three trials. The challenges of recruiting and retaining study participants is discussed. More importantly, the reliability and stability of the Tinnitus Handicap Inventory (THI) over long intervals is presented. The implications of this variability for the design and interpretation of future tinnitus studies is discussed.This article is part of a Special Issue entitled <Tinnitus>.

Spectral Measures of Loudness in Patients with Ataxic Dysarthriag

Dysarthria refers to a group of speech disorders characterized by neuromuscular involvement. This may affect different subsystems of speech like respiration, phonation, articulation and prosody differentially. Ataxic dysarthria is caused due to damage to the cerebellum. Excessive fluctuation in loudness or monoloudness typically characterizes ataxic dysarthria. These characteristics may be different in ataxic dysarthria due to lesions in different cerebellar loci. There is a need to address the spectral measures related to loudness in patients with lesions in different cerebellar loci.Seventeen subjects with ataxic dysarthria due to lesions in different cerebellar loci and matched controls performed an alternating motion rate (AMR) task. The recorded and digitized speech samples were analysed for spectral measures of maximum and minimum intensity. Intensity range was reduced in subjects with left (left superior paravermal, left anteroinferior), superior vermis, right superior paravermal and right anterosuperior lesions compared to normal controls in AMR task. It was comparable to normal controls in subjects with right posterosuperior lesions. Reduced intensity range seems to be because of increase in energy minima and decrease in energy maxima or due to decrease in energy maxima only.

Unilateral cochlear implant use promotes normal-like loudness perception in adolescents with childhood deafness.

Behavioral measures of cochlear implant (CI) device stimulation levels can be difficult to obtain in individuals with limited or no hearing experience. Loudness measures are particularly challenging. It would therefore be useful to have a battery of objective and behavioral measures to determine CI stimulation levels in listeners with childhood deafness. In the present study, the authors characterized loudness growth in 20 adolescents: 8 with normal hearing and 12 CI participants with pre/perilingual bilateral sensorineural hearing loss. They asked (1) do adolescent CI users with childhood deafness experience similar increases in loudness as their peers with normal hearing? and (2) can loudness be predicted by objective measures of auditory activity? The authors hypothesized that loudness perception would be significantly different between CI and normal-hearing groups and that it would correlate with objective measures. CI users were recruited from the Cochlear Implant Program at The Hospital for Sick Children and all had used unilateral Nucleus CIs for at least 2 years. The dynamic range for each participant was defined as the difference between the behavioral threshold and the electrically evoked stapedius reflex (ESR) threshold. Loudness growth was assessed within this range behaviorally on a continuous visual scale and objectively with physiological measures. Auditory brainstem responses (ABRs) and ESRs were recorded in both groups and electrically evoked compound action potentials (ECAPs) of the auditory nerve were recorded in addition in CI listeners. The regression line slopes of ECAP and ABR amplitude growth functions were then calculated and compared with behavioral loudness growth slopes in the upper portion (40-100%) and lower portion (0-40%) of the dynamic range. Electrical pulse stimuli (in CI users) and acoustic clicks (in normal-hearing participants) were presented within each participant's dynamic range. The mean dynamic range in CI listeners was more variable than in normal-hearing individuals. Despite this difference, loudness at the ESR threshold was not significantly different in CI adolescents from their normal-hearing peers, and CI users exhibited normal-like loudness growth. There was a significantly positive correlation between ECAP amplitude growth and loudness growth in CI users in the upper portion of the dynamic range, while ABR wave V amplitude growth was not related to loudness growth in either group. We confirmed that the ESR threshold is a good measure of comfortably loud levels in adolescents with cochlear implants and their normal-hearing peers. Adolescents using CIs show normal-like rates of loudness growth on average, despite having highly variable dynamic ranges of hearing. Individual rates of loudness growth in the upper dynamic range in CI users can be predicted by the rate of amplitude growth of the ECAP. Thus, the rate of neural recruitment with increasing CI current is important for loudness perception in pre/perilingually deaf listeners and should be considered when programming their CIs.

Acoustic reflex attenuation in phon loudness measurements

Equal Loudness-level Contours, ELC(f, L), represent the sound pressure level in dB SPL of tones at frequency f that are perceived by normal-hearing listeners as equally loud as a 1 kHz tone at L dB SPL. Loudness is defined relatively as L phons (Fletcher & Munson, 1933). ELC measurements by Lydolf and Moller (1997) included in the current ISO standard (Suzuki & Takeshima, JASA vol. 116, 2004), show systematic increases in ELC growth rate with loudness above 60 phons and below 1 kHz, which suggests middle-ear attenuation by the acoustic reflex (AR). A steady-state ELC model was assembled including known mechanisms: (1) middle ear transmission modified by a head-related-transfer-function, (2) compressive cochlear amplification (CA) for signaling loudness, (3) a negative feedback model for AR attenuation by CA inputs exceeding AR threshold, and (4) attenuation of pressure-field stimuli by trans-eardrum static pressure. Model parameters were calculated from ELC data using minimum-square-error estimation. AR attenuation below 1 kHz depends on AR attenuation at the 1 kHz loudness reference frequency, but predicted ELCs are relatively insensitive to it. An earlier psychophysical study of AR attenuation, including 1 kHz, is consistent with subject-dependent model predictions (Rabinowitz & Goldstein, JASA vol. 54, 1973; Rabinowitz, 1977). [NIH-Funded.]

Direct Comparison of Three Commercially Available Devices for Voice Ambulatory Monitoring and Biofeedback

Purpose: To provide a direct comparison of three commercially available devices for voice ambulatory monitoring and biofeedback to assist voice clinicians and researchers in choosing the device that best meets their needs. Methods: The Ambulatory Phonation Monitor (APM), VocaLog, and VoxLog were descriptively compared regarding cost, availability, physical characteristics, and operational features; and quantitatively compared regarding measures of loudness (dB sound pressure level [SPL]), pitch (fundamental frequency – F0), and phonation time. The quantitative comparison used simultaneous registrations acquired during a 90-minute lecture which also included a Smartphone-based system designed to capture the raw voice signal as a reference. Results: Differences regarding cost, physical characteristics, and operational features could influence device choice. All three devices register SPL and phonation time, and also biofeedback based on SPL. Furthermore, the APM and VoxLog provide monitoring and biofeedback for F0 with the associated capability of providing additional measures related to vocal dose. All devices produced comparable results for common measures, except for the overestimation of phonation time by the VocaLog. Conclusions: The cost, operational features, and performance characteristics of the three commercially available devices for voice ambulatory monitoring and biofeedback differ in ways that can significantly impact decisions about which one is best suited for a particular application.

Signal-Processing Strategy for Restoration of Cross-Channel Suppression in Hearing-Impaired Listeners

Because frequency components interact nonlinearly with each other inside the cochlea, the loudness growth of tones is relatively simple in comparison to the loudness growth of complex sounds. The term suppression refers to a reduction in the response growth of one tone in the presence of a second tone. Suppression is a salient feature of normal cochlear processing and contributes to psychophysical masking. Suppression is evident in many measurements of cochlear function in subjects with normal hearing, including distortion-product otoacoustic emissions (DPOAEs). Suppression is also evident, to a lesser extent, in subjects with mild-to-moderate hearing loss. This paper describes a hearing-aid signal-processing strategy that aims to restore both loudness growth and two-tone suppression in hearing-impaired listeners. The prescription of gain for this strategy is based on measurements of loudness by a method known as categorical loudness scaling. The proposed signal-processing strategy reproduces measured DPOAE suppression tuning curves and generalizes to any number of frequency components. The restoration of both normal suppression and normal loudness has the potential to improve hearing-aid performance and user satisfaction.

Psychoacoustic Assessment to Improve Tinnitus Diagnosis

The diagnosis of tinnitus relies on self-report. Psychoacoustic measurements of tinnitus pitch and loudness are essential for assessing claims and discriminating true from false ones. For this reason, the quantification of tinnitus remains a challenging research goal. We aimed to: (1) assess the precision of a new tinnitus likeness rating procedure with a continuous-pitch presentation method, controlling for music training, and (2) test whether tinnitus psychoacoustic measurements have the sensitivity and specificity required to detect people faking tinnitus. Musicians and non-musicians with tinnitus, as well as simulated malingerers without tinnitus, were tested. Most were retested several weeks later. Tinnitus pitch matching was first assessed using the likeness rating method: pure tones from 0.25 to 16 kHz were presented randomly to participants, who had to rate the likeness of each tone to their tinnitus, and to adjust its level from 0 to 100 dB SPL. Tinnitus pitch matching was then assessed with a continuous-pitch method: participants had to match the pitch of their tinnitus to an external tone by moving their finger across a touch-sensitive strip, which generated a continuous pure tone from 0.5 to 20 kHz in 1-Hz steps. The predominant tinnitus pitch was consistent across both methods for both musicians and non-musicians, although musicians displayed better external tone pitch matching abilities. Simulated malingerers rated loudness much higher than did the other groups with a high degree of specificity (94.4%) and were unreliable in loudness (not pitch) matching from one session to the other. Retest data showed similar pitch matching responses for both methods for all participants. In conclusion, tinnitus pitch and loudness reliably correspond to the tinnitus percept, and psychoacoustic loudness matches are sensitive and specific to the presence of tinnitus.

Subjective and Objective Parameters of the Adult Female Voice after Cricotracheal Resection and Dilation

We compared the voice outcomes after cricotracheal resection (CTR) and airway dilation in adult women. We performed long-term comprehensive voice assessments in 23 adult women treated for laryngotracheal stenosis, including acoustic and perceptual measurements of voice, videostroboscopy, the Voice Handicap Index, and an open-ended subjective questionnaire. Voice measures were abnormal in both groups. Objective pitch and loudness measurements were significantly more impaired after CTR than after dilation. Perceptual ratings of voice were worse after CTR than after dilation, particularly with regard to breathiness, pitch, and loudness. The CTR group was more likely to report a voice disorder, reported significantly more voice symptoms, and had higher voice handicap scores. Videostroboscopy was frequently abnormal in both groups, with more evidence of vocal hyperfunction after CTR. Self-ratings of breathing and swallowing were generally high in both groups, but voice satisfaction was rated lower after CTR. Voice was more significantly negatively impacted by CTR than by dilation. Surprisingly, many individuals in both groups reported improvements--a finding that possibly highlights the impact of laryngotracheal stenosis on airflow and vocal function before surgery. The importance of patient selection and preoperative counseling is emphasized, along with the potential need for voice therapy.

Assessing whether loud speech affects vowel formant values in toddlers

Extensive token-to-token variability is a widely-noted characteristic of child speech. This variability likely arises from several sources. In a recent analysis of vowel formants in the speech of toddlers, we observed that some children produced extreme ranges of F1 for the same target vowel, and that some high values of F1 were associated with a loud voice. Here, we undertake a systematic analysis of vowel formants as a function of perceived loud voice. Data were obtained from children 2–3 years of age producing many repetitions of the words “baby,” “ball,” “boy,” “bubble,” “moo,” and “pooh.” Since mouth-to-microphone distance varied, an acoustic measure of loudness was not possible. However, speaking level can affect voice quality and possibly other production features, and might be reliably perceptible nevertheless. All word productions suitable for acoustic analysis will be auditorily assessed by naïve listeners as having “regular voice” or “loud voice.” We will then determine whether productions judged as loud vary systematically in their formant frequencies. If so, it would suggest that researchers studying young child speech should attempt to limit extreme variations in vocal loudness, particularly if they are interested in acoustic measures of variability.

Automatic detection of breathy voiced vowels in Gujarati speech

This paper proposes a method for automatic detection of breathy voiced vowels in continuous Gujarati speech. As breathy voice is a specific phonetic feature predominantly present in Gujarati among Indian languages, it can be used for identifying Gujarati language. The objective of this paper is to differentiate breathy voiced vowels from modal voiced vowels based on loudness measure. Excitation source characteristics represented by loudness measure are used for differentiating the voice quality. In the proposed method, initially vowel regions in continuous speech are determined by using the knowledge of vowel onset points and epochs. Later, hypothesized vowel segments are classified by using loudness measure. Performance of the proposed method is evaluated on Gujarati speech utterances containing around 47 breathy and 192 modal vowels spoken by 5 male and 5 female speakers. Classification of vowels into breathy or modal voice is achieved with an accuracy of around 94 %.

Using Supervised Learning to Improve Monte Carlo Integral Estimation

Monte Carlo techniques are used to estimate the integrals of a function using randomly generated samples. The interest in uncertainty quantification and robust design makes calculating the expected values of such functions (e.g., performance measures) important. Recent developments in scramjets, aircraft technology forecasting, structural reliability, and robust low-boom aircraft designs use Monte Carlo techniques to ensure the appropriate quantification of uncertainties. Because of high variance and slow convergence, Monte Carlo techniques require a large number of function evaluations, limiting the fidelity of the tools that can be used to predict performance. Stacked Monte Carlo is presented, which is a new method for postprocessing an existing set of Monte Carlo samples to improve integral estimation. Stacked Monte Carlo is based on combining fitting functions with cross-validation and should reduce the variance of any type of Monte Carlo integral estimate (importance sampling, quasi-Monte Carlo, etc.) without adding bias. An extensive set of experiments is reported, confirming that the stacked Monte Carlo estimate is more accurate than both the unprocessed Monte Carlo estimate and the estimate from a functional fit. Stacked Monte Carlo is applied to estimate the fuel-burn metrics of future commercial aircraft and sonic boom loudness measures, and the efficiency of Monte Carlo is compared with that of more standard methods. It is shown that for negligible, additional, computational cost, significant increases in accuracy are gained.

Auditory reaction time measurements and equal-latency curves in the California sea lion (Zalophus californianus) and bottlenose dolphin (Tursiops truncatus)

Subjective equal-loudness contours are used to create weighting functions for human noise-mitigation criteria. Comparable direct measurements of subjective loudness with animal subjects are, however, difficult to conduct. Using methods similar to those used in previous mammalian studies, this study estimated subjective loudness through the measurement of response time (RT) in an auditory signal-detection task. Measurements were conducted in a sound-attenuating hut with a California sea lion and under water in a quiet pool with a bottlenose dolphin. Tonal stimuli were presented at supra- and near-threshold sound pressure levels (SPLs) using a method of constants. Median RT increased with decreasing SPL for both species across all tested frequencies. A Piéron function, which models RT as a function of SPL, was fitted to the RT-SPL curves in a nonlinear fashion. Equal-latency curves were based on the Piéron functions at each frequency. Preliminary results for the sea lion suggest that the equal-latency curves are similar to the audiogram at longer median RTs (~300 ms), with increasing deviation from the audiogram at the fastest median RTs (~200 ms). Continued testing with additional subjects will provide further data for designing marine mammal auditory weighting functions. [Funded by U.S. Navy Living Marine Resources Program.]

Modeling music perception in impaired listeners

We employ computational models of loudness and pitch perception to better understand the impact of sensorineural hearing loss on music perception, with the aim of guiding technology development for hearing-impaired listeners. Traditionally, hearing aid development has been geared towards improving speech intelligibility and has largely failed to provide adequate restoration of music to those with hearing loss. One difficulty with trying to improve music perception in impaired listeners is the absence of a good quantitative measure of music reception, analogous to speech reception measures like word-recognition rate. Psychoacoustic models for loudness and pitch allow us to guage quantitative parameters relevant to music perception and make predictions about the type of deficits listeners face. We examine the impact of hearing loss to predicted measures of loudness, specific loudness, pitch, and consonance and make suggestions on possible methods for restoration.

Relation between loudness in categorical units and loudness in phons and sones

Data are presented on the relation between loudness measured in categorical units (CUs) using a standardized loudness scaling method (ISO 16832, 2006) and loudness expressed as the classical standardized measures phon and sone. Based on loudness scaling of narrowband noise signals by 31 normal-hearing subjects, sound pressure levels eliciting the same categorical loudness were derived for various center frequencies. The results were comparable to the standardized equal-loudness level contours. A comparison between the loudness function in CUs at 1000 Hz and the standardized loudness function in sones indicates a cubic relation between the two loudness measures.