Loudness Variation Research Articles

Vocalization with semi-occluded airways is favorable for optimizing sound production.

Vocalization in mammals, birds, reptiles, and amphibians occurs with airways that have wide openings to free-space for efficient sound radiation, but sound is also produced with occluded or semi-occluded airways that have small openings to free-space. It is hypothesized that pressures produced inside the airway with semi-occluded vocalizations have an overall widening effect on the airway. This overall widening then provides more opportunity to produce wide-narrow contrasts along the airway for variation in sound quality and loudness. For human vocalization described here, special emphasis is placed on the epilaryngeal airway, which can be adjusted for optimal aerodynamic power transfer and for optimal acoustic source-airway interaction. The methodology is three-fold, (1) geometric measurement of airway dimensions from CT scans, (2) aerodynamic and acoustic impedance calculation of the airways, and (3) simulation of acoustic signals with a self-oscillating computational model of the sound source and wave propagation.

Timbre Vibrato Perception and Description

In music, vibrato consists of cyclic variations in pitch, loudness, or spectral envelope (hereafter, “timbre vibrato”—TV) or combinations of these. Here, stimuli with TV were compared with those having loudness vibrato (LV). In Experiment 1, participants chose from tones with different vibrato depth to match a reference vibrato tone. When matching to tones with the same vibrato type, 70% of the variance was explained by linear matching of depth. Less variance (40%) was explained when matching dissimilar vibrato types. Fluctuations in loudness were perceived as approximately the same depth as fluctuations in spectral envelope (i.e., about 1.3 times deeper than fluctuations in spectral centroid). In Experiment 2, participants matched a reference with test stimuli of varying depths and types. When the depths of the test and reference tones were similar, the same type was usually selected, over the range of vibrato depths. For very disparate depths, matches were made by type only about 50% of the time. The study revealed good, fairly linear sensitivity to vibrato depth regardless of vibrato type, but also some poorly understood findings between physical signal and perception of TV, suggesting that more research is needed in TV perception.

A novel study on perception–cognition scenario in music using deterministic and non-deterministic approach

In the last few decades, nonlinear science and chaos theory has provided several robust non-deterministic tools by means of which the complexity of a nonlinear audio waveform can be measured precisely. On the other hand, sound signal analysis in linear deterministic approach has reached a new dimension where a number of well equipped software have been developed which can minutely measure and control the basic parameters of sound like pitch, intensity, tempo etc. The main objective of the present work is to quantitatively study the changes in acoustic signal complexity (measured using chaos based fractal technique) with individual variation in pitch, loudness and timbre of a sound signal. EEG (Electroencephalography) was also performed on 10 participants to see how the neuro-cognitive attributes of a sound change, i.e. when these basic components — pitch, loudness and timbre of the sound vary, one at a time. Single strokes of a piano were recorded where pitch and loudness of the sound signals were varied one at a time keeping the other parameters fixed. Then the sounds of 14 different musical instruments playing the same pitch at same loudness were recorded, which effectively served the purpose of timbre variation. EEG experiment was conducted with these audio signals as stimuli for the participants. The multifractal spectral widths were calculated for all the music signals as well as the corresponding EEG signals using Multifractal Detrended Fluctuation Analysis (MFDFA) and compared with each other. The results point towards the direction of a correlation between the conventional linear parameters and the latest nonlinear features in the acoustic domain, while the changes in the multifractal values of the different EEG waves reveal new information about the cognition of the basic features of sound in human brain. This study is a novel attempt to provide new data in engulfing apparent objective (acoustics) - subjective (EEG) connection, which is highly needed for building any model for perception–cognition connectivity.

Face-voice space: Integrating visual and auditory cues in judgments of person distinctiveness.

Faces and voices each convey multiple cues enabling us to tell people apart. Research on face and voice distinctiveness commonly utilizes multidimensional space to represent these complex, perceptual abilities. We extend this framework to examine how a combined face-voice space would relate to its constituent face and voice spaces. Participants rated videos of speakers for their dissimilarity in face only, voice only, and face-voice together conditions. Multiple dimensional scaling (MDS) and regression analyses showed that whereas face-voice space more closely resembled face space, indicating visual dominance, face-voice distinctiveness was best characterized by a multiplicative integration of face-only and voice-only distinctiveness, indicating that auditory and visual cues are used interactively in person-distinctiveness judgments. Further, the multiplicative integration could not be explained by the small correlation found between face-only and voice-only distinctiveness. As an exploratory analysis, we next identified auditory and visual features that correlated with the dimensions in the MDS solutions. Features pertaining to facial width, lip movement, spectral centroid, fundamental frequency, and loudness variation were identified as important features in face-voice space. We discuss the implications of our findings in terms of person perception, recognition, and face-voice matching abilities.

T59. ACOUSTIC SPEECH MARKERS FOR SCHIZOPHRENIA

BackgroundClinicians routinely use impressions of speech as an element of mental status examination, including ‘pressured’ speech in mania and ‘monotone’ or ‘soft’ speech in depression or psychosis. In psychosis in particular, descriptions of speech are used to monitor (negative) symptom severity. Recent advances in computational linguistics have paved the way towards automated speech analyses as a biomarker for psychosis. In the present study, we assessed the diagnostic value of acoustic speech features in schizophrenia. We hypothesized that a classifier would be highly accurate (~ 80%) in classifying patients and healthy controls.MethodsNatural speech samples were obtained from 86 patients with schizophrenia and 77 age and gender matched healthy controls through a semi-structured interview, using a set of neutral open-ended questions. Symptom severity was rated by consensus rating of two trained researchers, blinded to phonetic analysis, with the Positive And Negative Syndrome Scale (PANSS). Acoustic features were extracted with OpenSMILE, employing the Geneva Acoustic Minimalistic Parameter Set (GeMAPS), which comprises standardized analyses of pitch (F0), formants (F1, F2 and F3, i.e. acoustic resonance frequencies that indicate the position and movement of the articulatory muscles during speech production), speech quality, length of voiced and unvoiced regions. Speech features were fed into a linear kernel support vector machine (SVM) with leave-one-out cross-validation to assess their value for psychosis diagnosis.ResultsDemographic analyses revealed no differences between patients with schizophrenia and healthy controls in age or parental education. An automated machine-learning speech classifier reached an accuracy of 82.8% in classifying patients with schizophrenia and controls on speech features alone. Important features in the model were variation in loudness, spectral slope (i.e. the gradual decay in energy in high frequency speech sounds) and the amount of voiced regions (i.e. segments of the interview where the participant was speaking). PANSS positive, negative and general scores were significantly correlated with pitch, formant frequencies and length of voiced and unvoiced regions.DiscussionThis study demonstrates that an algorithm using quantified features of speech can objectively differentiate patients with schizophrenia from controls with high accuracy. Further validation in an independent sample is required. Employing standardized parameter sets ensures easy replication and comparison of analyses and can be used for cross linguistic studies. Although at an early stage, the field of clinical computational linguistics introduces a powerful tool for diagnosis and prognosis of psychosis and neuropsychiatric disorders in general. We consider this new diagnostic tool to be of high potential given its ease of acquirement, low costs and patient burden. For example, this tool could easily be implemented as a smartphone app to be used in treatment settings.

Dysarthria enhancement mechanism under external clear speech instruction in Parkinson's disease, progressive supranuclear palsy and multiple system atrophy.

Clear speech refers to intentionally modifying conversational speech to maximise intelligibility. This study aimed to compare the speech behaviour of patients with progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and Parkinson's disease (PD) under conversational and clear speech conditions to gain greater pathophysiological insight. A total of 68 participants including 17 PD, 17 MSA, 17 PSP and 17 healthy controls (HC) performed two readings of the same standardized passage. During the first reading, participants were instructed to read the text in an ordinary way, while during the second reading to read the text as clearly as possible. Acoustic analyses were based upon measurements of mean loudness, loudness variability, pitch variability, vowel articulation, articulation rate and speech severity. During clear speech production, PD patients were able to achieve improvements mainly in loudness (p < 0.05) and pitch variability (p < 0.001), leading to a reduction in overall speech severity (p < 0.001), whereas PSP and MSA patients were able to modulate only articulation rate (p < 0.05). Contrary to HC and PD groups, which slowed or maintained articulation rate, PSP and MSA groups employed a markedly faster articulation rate under the clear speech condition indicating an opposing approach to speech adaptation. Patients with atypical Parkinsonism showed a different strategy to intentionally improve their speech performance following a simple request to produce speech more clearly compared to PD, suggesting important therapeutic implications for speech rehabilitation management.

Vocal Loudness Variation With Spectral Slope.

Objective This investigation addresses the loudness variations in sones achievable with spectral slope variations (higher harmonic energy) in human vocalization and compares it to the sound pressure level (SPL) variations typically reported in the voice range profile (VRP). Method The primary methodology was computational. The ISO standard 226 was used to convert SPL values to sones for a 125- to 1000-Hz range of fundamental frequency and a -3 dB/octave to -12 dB/octave range of spectral slope. In addition, a retrospective analysis of human subjects' VRPs was conducted, and the experimental results were compared to the theoretical results. Results A very small range of SPL variation (less than 5 dB) in the VRP can produce a large range of loudness. The sensitivity can be on the order of 4 sones per dB SPL change. Conclusion For vocalization in the modal register, loudness variation is not well described by SPL change in dB, especially at high fundamental frequencies where the SPL range in the VRP becomes very small but sizeable loudness variations are still possible.

Longitudinal Speech Change After Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease Patients: A 2-Year Prospective Study.

Speech disorders are among the most common adverse effects after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD) patients. However, longitudinal speech changes after STN-DBS are not fully understood. We performed a two-year prospective study on PD patients who underwent STN-DBS and analyzed changes in speech function to clarify factors predicting for speech deterioration. Twenty-five PD patients were assessed before and up to two years after STN implantation. Speech function was evaluated in the on-stimulation condition and 30 min after stimulation cessation using auditory-perceptual assessment. Patients who experienced overall worsening in speech intelligibility or naturalness ≥1 point during follow-up were classified into a deteriorated group (n = 16), with the remaining subjects being classified into a stable group (n = 9). Cognitive and motor functions were also assessed. The stable group had significantly better values of low volume, monoloudness, and asthenic voice subscores of the auditory-perceptual assessment in the on-stimulation condition compared with the off-stimulation condition. Imprecise consonants, excess loudness variation, and strained voice subscores were improved via cessation of stimulation in both groups. Before surgery, the deteriorated group had significantly lower scores in the Stroop Color-Word Test and Digit Span compared to the stable group. During follow-up, some subscores showed significant worsening in the on-stimulation condition in both groups. However, beneficial effects of STN-DBS on speech appeared to counterbalance negative effects of STN-DBS on speech function only in the stable group. Worse cognitive function may be a potential predictor for speech deterioration after STN-DBS in PD patients.

A Low-Noise Guitar Robot Featuring a New Class of Silent Actuators

This paper presents the development of the automatic string-plucking system of a guitar robot, which was designed to generate music without machine noise. The soft robotics approach led to the development of a novel silent actuator that utilizes soft elastomeric cones as cushioning to prevent impact noise. We present the method to design the elastomeric cone based on nonlinear finite element analysis. The silent feature of the silent actuator was confirmed by a noise test comparing the silent actuator with the conventional ones. We also present a new design of the robot fingers, which is quiet and capable of hurdling the string in the returning stroke. To enrich the music dynamics, loudness variation was created by simple open-loop control. As a sample performance test, an accompaniment music of the song “Five Hundred Miles” was played in front of an audience for their opinions. Lastly, in a speed test, the results showed that the speed limit of the plucking fingers can reach 720 PPM. A video of the robot playing “Five Hundred Miles” can be found in: https://www.youtube.com/watch?time_continue=3&v=dwdimrP6M2U .

Vowel Formants in Normal and Loud Speech.

Purpose This study evaluated how 1st and 2nd vowel formant frequencies (F1, F2) differ between normal and loud speech in multiple speaking tasks to assess claims that loudness leads to exaggerated vowel articulation. Method Eleven healthy German-speaking women produced normal and loud speech in 3 tasks that varied in the degree of spontaneity: reading sentences that contained isolated /i: a: u:/, responding to questions that included target words with controlled consonantal contexts but varying vowel qualities, and a recipe recall task. Loudness variation was elicited naturalistically by changing interlocutor distance. First and 2nd formant frequencies and average sound pressure level were obtained from the stressed vowels in the target words, and vowel space area was calculated from /i: a: u:/. Results Comparisons across many vowels indicated that high, tense vowels showed limited formant variation as a function of loudness. Analysis of /i: a: u:/ across speech tasks revealed vowel space reduction in the recipe retell task compared to the other 2. Loudness changes for F1 were consistent in direction but variable in extent, with few significant results for high tense vowels. Results for F2 were quite varied and frequently not significant. Speakers differed in how loudness and task affected formant values. Finally, correlations between sound pressure level and F1 were generally positive but varied in magnitude across vowels, with the high tense vowels showing very flat slopes. Discussion These data indicate that naturalistically elicited loud speech in typical speakers does not always lead to changes in vowel formant frequencies and call into question the notion that increasing loudness is necessarily an automatic method of expanding the vowel space. Supplemental Material https://doi.org/10.23641/asha.8061740.

Near-Field Variation of Loudness with Distance

The boundary element method was used to calculate the sound pressure levels at the two ears of an artificial head when a sound source was located in different directions and distances in the near field (within 1 m). Total loudness was then calculated by using a binaural loudness model. Results showed that, in the near field, total loudness does not always increase monotonically as the source distance decreases. As distance decreased (for bands with center frequencies above 2 kHz), generally loudness first decreased and then increased (creating a local minimum); and when the distance became very small, the loudness generally began to decrease again (loudness had a local maximum). The external surface model of the artificial head was explored computationally. Calculations confirmed that the local minimum and maximum were caused by scattering from the shoulders. The effect of the width of the shoulders on near-field loudness was also determined. Finally, psychoacoustic experiments were conducted on four subjects. Results confirmed the presence of a local minimum and maximum and supported the idea that scattering from the shoulders was the main cause.

Failed summons: Phonetic features of persistence and intensification in crisis negotiation

This paper explores crisis negotiators' practices for summoning persons in crisis who are unavailable, unable or unwilling to respond. A corpus of audio recorded interactions between a UK police hostage and crisis negotiation unit and (suicidal) people in crisis was analysed. The analysis shows how low to moderate phonetic upgrades in pitch, and small variations in loudness, duration and articulatory setting are associated with interactionally ‘re-doing’ a subsequent summons. In contrast, marked phonetic upgrades in pitch, loudness and articulatory setting are associated with an increase in danger or concern. And whereas phonetic upgrading of a self-repeated summons is found in cases where the recipient is unavailable, unable or unwilling to respond, phonetic downgrading treats the silence as responsiveness in progress, where the summons repetition does extra work to further secure the person's joint attention to a projected new course of action. I discuss the complexities of applying an ‘upgrade-downgrade’ continuum to account for repeated action and consider the wider implications of phonetic design on crisis management.

Filling Sound with Space: An elemental approach to sound spatialisation

This research introduces different compositional techniques involving the use of sound spatialisation. These permit the incorporation of sound distortions produced by the real space, the body and the auditory system into low-, middle- and large-scale musical structures, allowing sound spatialisation to become a fundamental parameter of the three compositions presented here. An important characteristic of these pieces is the exclusive use of sine waves and other time-invariant sound signals. Even though these types of signals present no alterations in time, it is possible to perceive pitch, loudness and tone-colour variations when they move in space, due to the psychoacoustic processes involved in spatial hearing. To emphasise the perception of such differences, this research proposes dividing a tone into multiple sound units and spreading these in space using several loudspeakers arranged around the listener. In addition to the perception of sound attribute variations, it is also possible to create dynamic rhythms and textures that depend almost exclusively on how sound units are arranged in space. Such compositional procedures help to overcome to some degree the unnaturalness implicit when using synthetic-generated sounds; through them, it is possible to establish cause–effect relationships between sound movement, on the one hand, and the perception of sound attribute, rhythm and texture variations on the other. Another important consequence is the possibility of producing diffuse sound fields independently of the levels of reverberation in the room, and to create sound spaces of a particular spatial depth without using artificial delay or reverb.

Measuring variation of loudness in consideration of arrival direction and distribution width of sound

Measuring variation of loudness in consideration of arrival direction and distribution width of sound

The Effects of Stress Type, Vowel Identity, Baseline f0, and Loudness on the Relative Fundamental Frequency of Individuals With Healthy Voices

Relative fundamental frequency (RFF) has been investigated as a possible acoustic measure to assess laryngeal tension. This study aimed to identify possible factors in RFF stimuli (stress type, vowel identity, baseline f0, and loudness) that might also affect RFF values. Fifteen speakers with healthy voices produced short RFF stimuli (vowel-/f/-vowel; eg, /ɑfɑ/) in different conditions. They produced the stimuli with three different stress types and four different vowels. Participants also produced stimuli in three different baseline f0 conditions and three different loudness conditions. The mean RFF and within- and between-subject standard deviation (SD) of RFF were estimated for each stimuli condition. Stress type had a statistically significant effect on RFF means and within-subject SDs with a large effect size (P < 0.001). A significant but small effect of vowel identity was observed: onset 1 RFF values from /ɑ/ were higher than onset 1 RFF values from /u/ (P < 0.01). Baseline f0 had a significant effect on RFF values with a medium effect size (P < 0.05). Loudness did not have any significant effect on RFF, but onset 1 RFF values produced with soft voice showed an unexpectedly high between-subject SD. This evidence suggests that stress type is the most important factor to consider in RFF measurement. We also conclude that RFF may be somewhat resistant to vowel variation and small differences in baseline f0 and loudness, which may be beneficial in clinical settings.

Prospective crowdsensing versus retrospective ratings of tinnitus variability and tinnitus–stress associations based on the TrackYourTinnitus mobile platform

Many symptoms of neuropsychiatric disorders, such as tinnitus, are subjective and vary over time. Usually, in interviews or self-report questionnaires, patients are asked to retrospectively report symptoms as well as their severity, duration and influencing factors. However, only little is known to what degree such retrospective reports reflect the actual experiences made in daily life. Mobile technologies can remedy this deficiency. In particular, mobile self-help services allow patients to prospectively record symptoms and their severity at the time (or shortly after) they occur in daily life. In this study, we present results we obtained with the mobile crowdsensing platform TrackYourTinnitus. In particular, we show that there is a discrepancy between prospective and retrospective assessments. To be more precise, we show that the prospective variation of tinnitus loudness does not differ between the users who retrospectively rate tinnitus loudness as “varying” and the ones who retrospectively rate it as “non-varying.” As another result, the subjectively reported stress-level was positively correlated with tinnitus (loudness and distress) in the prospective assessments, even for users who retrospectively rated that stress reduces their tinnitus or has no effect on it. The results indicate that mobile technologies, like the TrackYourTinnitus crowdsensing platform, go beyond the role of an assistive service for patients by contributing to more detailed information about symptom variability over time and, hence, to more elaborated diagnostics and treatments.

Impact of phonatory frequency and intensity on glottal area waveform measurements derived from high-speed videoendoscopy

Measurements of glottal area waveform from high-speed videoendoscopy were made on vocally healthy females (n = 41) and males (n = 25) during sustained /i/ production at typical pitch and loudness, high pitch, and soft phonation. Three trials of each condition were performed yielding 594 samples. Statistical analysis of glottal cycle quotients (open quotient (OQ), speed quotient (SQ), rate quotient (RQ), glottal gap index (GGI)), glottal cycle periodicity (amplitude, time (TP)), glottal cycle symmetry (phase asymmetry index, spatial symmetry index, and amplitude symmetry index), glottal area derivative (maximum area declination rate (MADR)), and mechanical stress measures (stiffness index (SI), amplitude-to-length ratio (ALR)) revealed that only SI varied systematically across pitch and loudness conditions for males and females. Variations in pitch and loudness results in changes in SI, ALR, RQ, MADR, and SQ for females, whereas variations in target pitch and loudness results in changes in SI, ALR, RQ, MADR, GGI, OQ, and TP for male speakers. Carefully selecting the laryngeal parameters derived from high-speed videoendoscopy has the potential to provide insights clinically into the known laryngeal biomechanics expected for the increase in pitch and reduction in vocal loudness.

Characteristics of motor speech phenotypes in multiple sclerosis

BackgroundMotor speech disorders in multiple sclerosis (MS) are poorly understood and their quantitative, objective acoustic characterization remains limited. Additionally, little data regarding relationships between the severity of speech disorders and neurological involvement in MS, as well as the contribution of pyramidal and cerebellar functional systems on speech phenotypes, is available. MethodsSpeech data were acquired from 141 MS patients with Expanded Disability Status Scale (EDSS) ranging from 1 to 6.5 and 70 matched healthy controls. Objective acoustic speech assessment including subtests on phonation, oral diadochokinesis, articulation and prosody was performed. ResultsThe prevalence of dysarthria in our MS cohort was 56% while the severity was generally mild and primarily consisted of a combination of spastic and ataxic components. Prosodic-articulatory disorder presenting with monopitch, articulatory decay, excess loudness variations and slow rate was the most salient. Speech disorders reflected subclinical motor impairment with 78% accuracy in discriminating between a subgroup of asymptomatic MS (EDSS < 2.0) and control speakers. Speech disorder severity was related to the severity of neurological involvement. Decreased articulation rate was moderately correlated to EDSS as well as all subtests of the multiple sclerosis functional composite. The strongest correlation was observed between irregular oral diadochokinesis and the 9-Hole Peg Test (r = − 0.65, p < 0.001). Irregular oral diadochokinesis and excess loudness variations significantly separated pure pyramidal and mixed pyramidal-cerebellar MS subgroups. ConclusionsAutomated speech analyses may provide valuable biomarkers of disease progression in MS as dysarthria represents common and early manifestation that reflects disease disability and underlying pyramidal-cerebellar pathophysiology.

Arytenoid cartilage movements are hypokinetic in Parkinson's disease: A quantitative dynamic computerised tomographic study.

BackgroundVoice change is one of the earliest features of Parkinson’s disease. However, quantitative studies of vocal fold dynamics which are needed to provide insight into disease biology, aid diagnosis, or track progression, are few.MethodsWe therefore quantified arytenoid cartilage movements and glottic area during repeated phonation in 15 patients with Parkinson’s disease (symptom duration < 6 years) and 19 controls, with 320-slice computerised tomography (CT). We related these measures to perceptual voice evaluations and spirometry. We hypothesised that Parkinson’s disease patients have a smaller inter-arytenoid distance, a preserved or larger glottic area because vocal cord bowing has previously been reported, less variability in loudness, more voice dysdiadochokinesis and breathiness and a shortened phonation time because of arytenoid hypokinesis relative to glottic area.ResultsInter-arytenoid distance in Parkinson’s disease patients was moderately smaller (Mdn = 0.106, IQR = 0.091–0.116) than in controls (Mdn = 0.132, IQR = 0.116–0.166) (W = 212, P = 0.015, r = −0.42), normalised for anatomical and other inter-subject variance, analysed with two-tailed Wilcoxon’s rank sum test. This finding was confirmed in a linear mixed model analysis—Parkinson’s disease significantly predicted a reduction in the dependent variable, inter-arytenoid distance (b = −0.87, SEb = 0.39, 95% CI [−1.66, −0.08], t(31) = −2.24, P = 0.032). There was no difference in glottic area. On perceptual voice evaluation, patients had more breathiness and dysdiadochokinesis, a shorter maximum phonation time, and less variability in loudness than controls. There was no difference in spirometry after adjustment for smoking history.ConclusionsAs predicted, vocal fold adduction movements are reduced in Parkinson’s disease on repeated phonation but glottic area is maintained. Some perceptual characteristics of Parkinsonian speech reflect these changes. We are the first to use 320-slice CT to study laryngeal motion. Our findings indicate how Parkinson’s disease affects intrinsic laryngeal muscle position and excursion.

Manifestation of peripherial coding in the effect of increasing loudness and enhanced discrimination of the intensity of tone bursts before and after tone burst noise

To find the possible reasons for the midlevel elevation of the Weber fraction in intensity discrimination of a tone burst, a comparison was performed for the complementary distributions of spike activity of an ensemble of space nerves, such as the distribution of time instants when spikes occur, the distribution of interspike intervals, and the autocorrelation function. The distribution properties were detected in a poststimulus histogram, an interspike interval histogram, and an autocorrelation histogram—all obtained from the reaction of an ensemble of model space nerves in response to an auditory noise burst–useful tone burst complex. Two configurations were used: in the first, the peak amplitude of the tone burst was varied and the noise amplitude was fixed; in the other, the tone burst amplitude was fixed and the noise amplitude was varied. Noise could precede or follow the tone burst. The noise and tone burst durations, as well as the interval between them, was 4 kHz and corresponded to the characteristic frequencies of the model space nerves. The profiles of all the mentioned histograms had two maxima. The values and the positions of the maxima in the poststimulus histogram corresponded to the amplitudes and mutual time position of the noise and the tone burst. The maximum that occurred in response to the tone burst action could be a basis for the formation of the loudness of the latter (explicit loudness). However, the positions of the maxima in the other two histograms did not depend on the positions of tone bursts and noise in the combinations. The first maximum fell in short intervals and united intervals corresponding to the noise and tone burst durations. The second maximum fell in intervals corresponding to a tone burst delay with respect to noise, and its value was proportional to the noise amplitude or tone burst amplitude that was smaller in the complex. An increase in tone burst or noise amplitudes was caused by nonlinear variations in the two maxima and the ratio between them. The size of the first maximum in the of interspike interval distribution could be the basis for the formation of the loudness of the masked tone burst (implicit loudness), and the size of the second maximum, for the formation of intensity in the periodicity pitch of the complex. The auditory effect of the midlevel enhancement of tone burst loudness could be the result of variations in the implicit tone burst loudness caused by variations in tone-burst or noise intensity. The reason for the enhancement of the Weber fraction could be competitive interaction between such subjective qualities as explicit and implicit tone-burst loudness and the intensity of the periodicity pitch of the complex.