Loudness Growth Research Articles

10 Hz Amplitude Modulated Sounds Induce Short-Term Tinnitus Suppression.

Objectives: Acoustic stimulation or sound therapy is proposed as a main treatment option for chronic subjective tinnitus. To further probe the field of acoustic stimulations for tinnitus therapy, this exploratory study compared 10 Hz amplitude modulated (AM) sounds (two pure tones, noise, music, and frequency modulated (FM) sounds) and unmodulated sounds (pure tone, noise) regarding their temporary suppression of tinnitus loudness. First, it was hypothesized that modulated sounds elicit larger temporary loudness suppression (residual inhibition) than unmodulated sounds. Second, with manipulation of stimulus loudness and duration of the modulated sounds weaker or stronger effects of loudness suppression were expected, respectively.Methods: We recruited 29 participants with chronic tonal tinnitus from the multidisciplinary Tinnitus Clinic of the University of Regensburg. Participants underwent audiometric, psychometric and tinnitus pitch matching assessments followed by an acoustic stimulation experiment with a tinnitus loudness growth paradigm. In a first block participants were stimulated with all of the sounds for 3 min each and rated their subjective tinnitus loudness to the pre-stimulus loudness every 30 s after stimulus offset. The same procedure was deployed in the second block with the pure tone AM stimuli matched to the tinnitus frequency, manipulated in length (6 min), and loudness (reduced by 30 dB and linear fade out). Repeated measures mixed model analyses of variance (ANOVA) were calculated to assess differences in loudness growth between the stimuli for each block separately.Results: First, we found that all sounds elicit a short-term suppression of tinnitus loudness (seconds to minutes) with strongest suppression right after stimulus offset [F(6, 1331) = 3.74, p < 0.01]. Second, similar to previous findings we found that AM sounds near the tinnitus frequency produce significantly stronger tinnitus loudness suppression than noise [vs. Pink noise: t(27) = −4.22, p < 0.0001]. Finally, variants of the AM sound matched to the tinnitus frequency reduced in sound level resulted in less suppression while there was no significant difference observed for a longer stimulation duration. Moreover, feasibility of the overall procedure could be confirmed as scores of both tinnitus loudness and questionnaires were lower after the experiment [tinnitus loudness: t(27) = 2.77, p < 0.01; Tinnitus Questionnaire: t(27) = 2.06, p < 0.05; Tinnitus Handicap Inventory: t(27) = 1.92, p = 0.065].Conclusion: Taken together, these results imply that AM sounds, especially in or around the tinnitus frequency, may induce larger suppression than unmodulated sounds. Future studies should thus evaluate this approach in longitudinal studies and real life settings. Furthermore, the putative neural relation of these sound stimuli with a modulation rate in the EEG α band to the observed tinnitus suppression should be probed with respective neurophysiological methods.

Exploring emotional responses to orchestral gestures

Research on emotional responses to music indicates that prominent changes in instrumentation and timbre elicit strong responses in listeners. However, there are few theories related to orchestration that would assist in interpreting these empirical findings. This article investigates listeners’ emotional responses to four types of orchestral gestures – large-scale timbral and textural changes that occur in a coordinated, goal-directed manner – through an exploratory experiment that collected continuous responses of emotional intensity for musician and nonmusician listeners. A time series regression analysis was used to predict changes in emotional responses by modeling changes in several musical features, including instrumental texture, spectral centroid, loudness, and tempo. We demonstrate the application of a new visualization tool that compiles the emotional intensity ratings with score-based and performance-based musical features for qualitative and quantitative analysis. The results suggest that the response profiles differ for the four gestural types. Following the increasing growth of instrumental texture and loudness, the emotional intensity ratings climbed steadily for the gradual addition types. The ratings for the sudden addition gestures sharply increased in response to the rapid textural change, peaking toward the end of the excerpt. There was a slight tendency for musicians, but not nonmusicians, to anticipate the moment of sudden addition with heightened emotional responses. The responses to the reductive excerpts, both gradual and sudden, feature a plateau of lingering high emotional intensity, despite the decrease of other musical features. The visualization provided a method to observe the evolution of listeners’ emotional reactions in response to the orchestral gestures and assisted in interpreting the results of the time series regression analysis.

A history of loudness before 1950

Loudness is a perceptual correlate of the physical intensity of a sound, but the relationship between loudness and intensity is not simple. The derivation from loudness-matching data of equal-loudness contours for tones across frequency was described as early as 1927. However, the most influential work on loudness prior to 1950 was the formulation by Fletcher and Munson (1933) of a method for calculating the loudness of any steady sound from the intensities of its frequency components. In a subsequent publication, Fletcher and Munson (1937) described how the loudness of a tone changes in the presence of another tone, which is a phenomenon known as masking. Stevens (1936) made extensive contributions to the theory of loudness scaling and methods for loudness measurement. Miller (1947) discovered that “just detectable increments in intensity” were of the same order of magnitude for noise as for pure tones.” Dix et al. (1948) suggested a clinical use in differential diagnosis of hearing loss for the phenomenon known as loudness recruitment, which is defined as an abnormally-rapid loudness growth. In part because of its relevance to the remediation of hearing loss, the measurement, quantification, and prediction of loudness continue to be active areas of psychophysical research.

Repeated Measurement of Absolute and Relative Judgments of Loudness: Clinical Relevance for Prescriptive Fitting of Aided Target Gains for soft, Comfortable, and Loud, But Ok Sound Levels.

This study was undertaken with the purpose of streamlining clinical measures of loudness growth to facilitate and enhance prescriptive fitting of nonlinear hearing aids. Repeated measures of loudness at 500 and 3,000 Hz were obtained bilaterally at monthly intervals over a 6-month period from three groups of young adult listeners. All volunteers had normal audiometric hearing sensitivity and middle ear function, and all denied problems related to sound tolerance. Group 1 performed judgments of soft and loud, but OK for presentation of ascending sound levels. We defined these judgments operationally as absolute judgments of loudness. Group 2 initially performed loudness judgments across a continuum of seven loudness categories ranging from judgments of very soft to uncomfortably loud for presentation of ascending sound levels per the Contour Test of Loudness; we defined these judgments as relative judgments of loudness. In the same session, they then performed the absolute judgments for soft and loud, but OK sound levels. Group 3 performed the same set of loudness judgments as did group 2, but the task order was reversed such that they performed the absolute judgments initially within each test session followed by the relative judgments. The key findings from this study were as follows: (1) Within group, the absolute and relative tasks yielded clinically similar judgments for soft and for loud, but OK sound levels. These judgments were largely independent of task order, ear, frequency, or trial order within a given session. (2) Loudness judgments increased, on average, by ∼3 dB between the first and last test session, which is consistent with the commonly reported acclimatization effect reported for incremental changes in loudness discomfort levels as a consequence of chronic bilateral hearing aid use. (3) Measured and predicted comfortable judgments of loudness were in good agreement for the individual listener and for groups of listeners. These comfortable judgments bisect the measured levels judged for soft and for loud, but OK sounds. (4) Loudness judgments within the same loudness category varied across listeners within group by as much as 50 to 60 dB. Such large variation in judgments of loudness is problematic, especially because hearing-impaired listeners are known to exhibit similarly large ranges of intersubject response variation and, yet, poplar prescriptive fitting strategies continue to use average rather than individual loudness data to fit nonlinear hearing aids. The primary conclusions drawn from these findings are that reliable absolute judgments of soft and loud, but OK are clinically practical and economical to measure and, from these judgments, good estimates of comfortable loudness can also be predicted for individuals or for groups of listeners. Such loudness data, as measured as described in this report, offer promise for streamlining and enhancing prescriptive fitting of nonlinear hearing aids to target gain settings for soft (audible), comfortable, and loud, but OK (tolerable) sound inputs for the individual listener.

Comparison of Loudness Growth Function in Normal Hearing Individuals and Impaired Aided Hearing

Recent advancement in digital hearing aids has the flexibility to restore the lost compressive nonlinearity of cochlea by compression circuits. The current study is aimed at studying the loudness growth functions in normal hearing and hearing impaired adults those who use compression hearing aids. Categorical loudness scaling was assessed in both the normal hearing and hearing impaired adults with hearing aid. There frequencies were tested viz. 500 Hz, 1000 Hz and 2000 Hz. The hearing aid programme was held constant (NAL-NL1) across participants. The results revealed a significant main effect of group on loudness growth function; where the loudness growth grew steeper for low to moderately intense sounds in hearing impaired than for normal hearers. This implies, the differences in loudness growth function persist in hearing impaired even after fitting with an appropriate compression hearing aids.

The Relationship Between Intensity Coding and Binaural Sensitivity in Adults With Cochlear Implants.

Many bilateral cochlear implant users show sensitivity to binaural information when stimulation is provided using a pair of synchronized electrodes. However, there is large variability in binaural sensitivity between and within participants across stimulation sites in the cochlea. It was hypothesized that within-participant variability in binaural sensitivity is in part affected by limitations and characteristics of the auditory periphery which may be reflected by monaural hearing performance. The objective of this study was to examine the relationship between monaural and binaural hearing performance within participants with bilateral cochlear implants. Binaural measures included dichotic signal detection and interaural time difference discrimination thresholds. Diotic signal detection thresholds were also measured. Monaural measures included dynamic range and amplitude modulation detection. In addition, loudness growth was compared between ears. Measures were made at three stimulation sites per listener. Greater binaural sensitivity was found with larger dynamic ranges. Poorer interaural time difference discrimination was found with larger difference between comfortable levels of the two ears. In addition, poorer diotic signal detection thresholds were found with larger differences between the dynamic ranges of the two ears. No relationship was found between amplitude modulation detection thresholds or symmetry of loudness growth and the binaural measures. The results suggest that some of the variability in binaural hearing performance within listeners across stimulation sites can be explained by factors nonspecific to binaural processing. The results are consistent with the idea that dynamic range and comfortable levels relate to peripheral neural survival and the width of the excitation pattern which could affect the fidelity with which central binaural nuclei process bilateral inputs.

The Growth of Loudness in Cochlear Implant Listeners; Possible Developmental Effects?

The Growth of Loudness in Cochlear Implant Listeners; Possible Developmental Effects?

Effect of Pulse Polarity on Thresholds and on Non-monotonic Loudness Growth in Cochlear Implant Users.

Most cochlear implants (CIs) activate their electrodes non-simultaneously in order to eliminate electrical field interactions. However, the membrane of auditory nerve fibers needs time to return to its resting state, causing the probability of firing to a pulse to be affected by previous pulses. Here, we provide new evidence on the effect of pulse polarity and current level on these interactions. In experiment 1, detection thresholds and most comfortable levels (MCLs) were measured in CI users for 100-Hz pulse trains consisting of two consecutive biphasic pulses of the same or of opposite polarity. All combinations of polarities were studied: anodic-cathodic-anodic-cathodic (ACAC), CACA, ACCA, and CAAC. Thresholds were lower when the adjacent phases of the two pulses had the same polarity (ACCA and CAAC) than when they were different (ACAC and CACA). Some subjects showed a lower threshold for ACCA than for CAAC while others showed the opposite trend demonstrating that polarity sensitivity at threshold is genuine and subject- or electrode-dependent. In contrast, anodic (CAAC) pulses always showed a lower MCL than cathodic (ACCA) pulses, confirming previous reports. In experiments 2 and 3, the subjects compared the loudness of several pulse trains differing in current level separately for ACCA and CAAC. For 40% of the electrodes tested, loudness grew non-monotonically as a function of current level for ACCA but never for CAAC. This finding may relate to a conduction block of the action potentials along the fibers induced by a strong hyperpolarization of their central processes. Further analysis showed that the electrodes showing a lower threshold for ACCA than for CAAC were more likely to yield a non-monotonic loudness growth. It is proposed that polarity sensitivity at threshold reflects the local neural health and that anodic asymmetric pulses should preferably be used to convey sound information while avoiding abnormal loudness percepts.

Loudness Scaling Test Based on Categorical Perception

AbstractThe main goal of this research study is focused on creating a method for loudness scaling based on categorical perception. Its main features, such as: way of testing, calibration procedure for securing reliable results, employing natural test stimuli, etc., are described in the paper and assessed against a procedure that uses 1/2-octave bands of noise (LGOB) for the loudness growth estimation. The Mann-Whitney U-test is employed to check whether the proposed method is statistically equivalent to LGOB. It is shown that loudness functions obtained in both methods are similar in the statistical context. Moreover, the band-filtered musical instrument signals are experienced as more pleasant than the narrow-band noise stimuli and the proposed test is performed in a shorter time. The method proposed may be incorporated into fitting hearing strategies or used for checking individual loudness growth functions and adapting them to the comfort level settings while listening to music.

Autophonic Loudness of Singers in Simulated Room Acoustic Environments

This paper aims to study the effect of room acoustics and phonemes on the perception of loudness of one's own voice (autophonic loudness) for a group of trained singers. For a set of five phonemes, 20 singers vocalized over several autophonic loudness ratios, while maintaining pitch constancy over extreme voice levels, within five simulated rooms. There were statistically significant differences in the slope of the autophonic loudness function (logarithm of autophonic loudness as a function of voice sound pressure level) for the five phonemes, with slopes ranging from 1.3 (/a:/) to 2.0 (/z/). There was no significant variation in the autophonic loudness function slopes with variations in room acoustics. The autophonic room response, which represents a systematic decrease in voice levels with increasing levels of room reflections, was also studied, with some evidence found in support. Overall, the average slope of the autophonic room response for the three corner vowels (/a:/, /i:/, and /u:/) was -1.4 for medium autophonic loudness. The findings relating to the slope of the autophonic loudness function are in agreement with the findings of previous studies where the sensorimotor mechanisms in regulating voice were shown to be more important in the perception of autophonic loudness than hearing of room acoustics. However, the role of room acoustics, in terms of the autophonic room response, is shown to be more complicated, requiring further inquiry. Overall, it is shown that autophonic loudness grows at more than twice the rate of loudness growth for sounds created outside the human body.

Auditory Model-Based Dynamic Compression Controlled by Subband Instantaneous Frequency and Speech Presence Probability Estimates

Sensorineural hearing loss typically results in elevated thresholds and steepened loudness growth significantly conditioned by a damage of outer hair cells (OHC). In hearing aids, amplification and dynamic compression aim at widening the limited available dynamic range. However, speech perception particularly in complex acoustic scenes often remains difficult. Here, a physiologically motivated, fast acting, model-based dynamic compression algorithm (MDC) is introduced which aims at restoring the behaviorally estimated basilar membrane input–output (BM I/O) function in normal-hearing listeners. A system-specific gain prescription rule is suggested, based on the same model BM I/O function and a behavioral estimate of the individual OHC loss. Cochlear off-frequency component suppression is mimicked using an instantaneous frequency (IF) estimate. Increased loudness as a consequence of widened filters in the impaired system is considered in a further compensation stage. In an extended version, a subband estimate of the speech presence probability (MDC+SPP) additionally provides speech-selective amplification in stationary noise. Instrumental evaluation revealed that the IF control enhances the spectral contrast of vowels and benefits in quality predictions at higher signal-to-noise ratios (SNRs) were observed. Compared with a conventional multiband dynamic compressor, MDC achieved objective quality and intelligibility benefits for a competing talker at lower SNRs. MDC+SPP outperformed the conventional compressor in the quality predictions and reached comparable instrumental speech intelligibility as achieved with linear amplification. The proposed algorithm provides a first promising basis for auditory model-based compression with signal-type- and bandwidth-dependent gains.

Auditory steady-state responses as neural correlates of loudness growth

The aim of this study was to find an objective estimate of individual, complete loudness growth functions based on auditory steady-state responses. Both normal-hearing and hearing-impaired listeners were involved in two behavioral loudness growth tasks and one EEG recording session. Behavioral loudness growth was measured with Absolute Magnitude Estimation and a Graphic Rating Scale with loudness categories. Stimuli were sinusoidally amplitude-modulated sinusoids with carrier frequencies of either 500 Hz or 2000 Hz, a modulation frequency of 40 Hz, a duration of 1 s, and presented at intensities encompassing the participants’ dynamic ranges. Auditory steady-state responses were evoked by the same stimuli using durations of at least 5 min. Results showed that there was a good correspondence between the relative growth of the auditory steady-state response amplitudes and the behavioral loudness growth responses for each participant of both groups of listeners. This demonstrates the potential for a more individual, objective, and automatic fitting of hearing aids in future clinical practice.

Horizontal sound localization in cochlear implant users with a contralateral hearing aid

Interaural differences in sound arrival time (ITD) and in level (ILD) enable us to localize sounds in the horizontal plane, and can support source segregation and speech understanding in noisy environments. It is uncertain whether these cues are also available to hearing-impaired listeners who are bimodally fitted, i.e. with a cochlear implant (CI) and a contralateral hearing aid (HA).Here, we assessed sound localization behavior of fourteen bimodal listeners, all using the same Phonak HA and an Advanced Bionics CI processor, matched with respect to loudness growth. We aimed to determine the availability and contribution of binaural (ILDs, temporal fine structure and envelope ITDs) and monaural (loudness, spectral) cues to horizontal sound localization in bimodal listeners, by systematically varying the frequency band, level and envelope of the stimuli.The sound bandwidth had a strong effect on the localization bias of bimodal listeners, although localization performance was typically poor for all conditions. Responses could be systematically changed by adjusting the frequency range of the stimulus, or by simply switching the HA and CI on and off. Localization responses were largely biased to one side, typically the CI side for broadband and high-pass filtered sounds, and occasionally to the HA side for low-pass filtered sounds. HA-aided thresholds better than 45 dB HL in the frequency range of the stimulus appeared to be a prerequisite, but not a guarantee, for the ability to indicate sound source direction.We argue that bimodal sound localization is likely based on ILD cues, even at frequencies below 1500 Hz for which the natural ILDs are small. These cues are typically perturbed in bimodal listeners, leading to a biased localization percept of sounds. The high accuracy of some listeners could result from a combination of sufficient spectral overlap and loudness balance in bimodal hearing.

Effects of Sound-Induced Hearing Loss and Hearing Aids on the Perception of Music

Exposure to high-level music produces several physiological changes in the auditory system that lead to a variety of perceptual effects. Damage to the outer hair cells within the cochlea leads to a loss of sensitivity to weak sounds, loudness recruitment (a more rapid than normal growth of loudness with increasing sound level), and reduced frequency selectivity. Damage to inner hair cells and/or synapses leads to degeneration of neurons in the auditory nerve and to a reduced flow of information to the brain. This leads to poorer auditory discrimination and may contribute to reduced sensitivity to the temporal fine structure of sounds and to poor pitch perception. Hearing aids compensate for the effects of threshold elevation and loudness recruitment via multichannel amplitude compression, but they do not compensate for reduced frequency selectivity or loss of inner hair cells/synapses/neurons. Multichannel compression can impair some aspects of the perception of music, such as the ability to hear out one instrument or voice from a mixture. The limited frequency range and irregular frequency response of most hearing aids is associated with poor sound quality for music. Finally, systems for reducing acoustic feedback can have undesirable side effects when listening to music.

The relationship between the electrical stapedial muscle reflex threshold and electrical and behavioral measures in cochlear implant patients

Programming of multichannel cochlear implants (CIs) requires subjective responses to a series of sophisticated psychophysical percepts. It is often difficult for young prelinguistically deaf children to provide adequate responses for device fitting. This is especially true in setting levels of maximum comfortable loudness, whereby failure to indicate growth of loudness may result in elevation of stimulus levels to the threshold of pain. The acoustic or stapedial muscle reflex has been used previously to provide objective confirmation of acoustic stimulation, and there have been attempts to use the reflex in hearing-aid fitting. It has also been suggested that electrically elicited middle-ear muscle reflexes [electrically evoked stapedial reflex threshold (ESRT)] may have applicability in confirming and quantifying electrical stimulation through a CI. To assess the relationship between ESRT characteristics and levels of loudness perception with CIs, determine the reliability of the response, and investigate the potential use of ESRT in CI programming, 26 prelinguistically deafened CI users were evaluated. Reflexes have also been attempted on 312 electrodes, with responses present in 213 (68.3%). Comfort levels predicted by subjective judgments were highly correlated with the ESRT in individuals with CI. ESRT provides an objective, accurate, and rapid method of estimating maximum comfortable loudness levels, which may be useful in the initial programming of young implant recipients.

Suprathreshold auditory processing deficits in noise: Effects of hearing loss and age

People with sensorineural hearing loss generally suffer from a reduced ability to understand speech in complex acoustic listening situations, particularly when background noise is present. In addition to the loss of audibility, a mixture of suprathreshold processing deficits is possibly involved, like altered basilar membrane compression and related changes, as well as a reduced ability of temporal coding. A series of 6 monaural psychoacoustic experiments at 0.5, 2, and 6 kHz was conducted with 18 subjects, divided equally into groups of young normal-hearing, older normal-hearing and older hearing-impaired listeners, aiming at disentangling the effects of age and hearing loss on psychoacoustic performance in noise. Random frequency modulation detection thresholds (RFMDTs) with a low-rate modulator in wide-band noise, and discrimination of a phase-jittered Schroeder-phase from a random-phase harmonic tone complex are suggested to characterize the individual ability of temporal processing. The outcome was compared to thresholds of pure tones and narrow-band noise, loudness growth functions, auditory filter bandwidths, and tone-in-noise detection thresholds. At 500 Hz, results suggest a contribution of temporal fine structure (TFS) to pure-tone detection thresholds. Significant correlation with auditory thresholds and filter bandwidths indicated an impact of frequency selectivity on TFS usability in wide-band noise. When controlling for the effect of threshold sensitivity, the listener's age significantly correlated with tone-in-noise detection and RFMDTs in noise at 500 Hz, showing that older listeners were particularly affected by background noise at low carrier frequencies.

Abnormal Auditory Gain in Hyperacusis: Investigation with a Computational Model.

Hyperacusis is a frequent auditory disorder that is characterized by abnormal loudness perception where sounds of relatively normal volume are perceived as too loud or even painfully loud. As hyperacusis patients show decreased loudness discomfort levels (LDLs) and steeper loudness growth functions, it has been hypothesized that hyperacusis might be caused by an increase in neuronal response gain in the auditory system. Moreover, since about 85% of hyperacusis patients also experience tinnitus, the conditions might be caused by a common mechanism. However, the mechanisms that give rise to hyperacusis have remained unclear. Here, we have used a computational model of the auditory system to investigate candidate mechanisms for hyperacusis. Assuming that perceived loudness is proportional to the summed activity of all auditory nerve (AN) fibers, the model was tuned to reproduce normal loudness perception. We then evaluated a variety of potential hyperacusis gain mechanisms by determining their effects on model equal-loudness contours and comparing the results to the LDLs of hyperacusis patients with normal hearing thresholds. Hyperacusis was best accounted for by an increase in non-linear gain in the central auditory system. Good fits to the average patient LDLs were obtained for a general increase in gain that affected all frequency channels to the same degree, and also for a frequency-specific gain increase in the high-frequency range. Moreover, the gain needed to be applied after subtraction of spontaneous activity of the AN, which is in contrast to current theories of tinnitus generation based on amplification of spontaneous activity. Hyperacusis and tinnitus might therefore be caused by different changes in neuronal processing in the central auditory system.

Discrimination of Hearing Disorder by Means of CLS and OAE in Vestibular Schwannoma

Currently a sensitive early diagnosis of small vestibular schwannoma is only possible by using magnetic resonance imaging (MRI). The main objective was a differentiation of the cochlear and retrocochlear component of small vestibular schwannoma with the help of categorial loudness scaling (CLS) and the growth function of otoacoustic emissions (DPOAE I/O-functions). 34 patients (gr. 1: 17 patients with vestibular schwannoma ≤15 mm, gr. 2: 17 matched patients with an inner ear hearing disorder) were examined. Besides audiological standard procedures they also underwent CLS according to the Würzburger auditory field and a generation of DPOAE I/O-functions was conducted on the probands. The gradients of the loudness growth function as part of the CLS and the DPOAE I/O-functions showed with few exceptions [500 Hz at 0-10 dB HL during CLS (p=0,040)] no significant differences between the groups (all p>0.05). A recruitment verification with the help of CLS was possible for tumors starting at a size of 5.45,mm at 3,000 and 4,000 Hz, respectively for tumors exceeding the size of 6.85 mm at 6,000 Hz with 100% sensitivity but only low specificity. A differentiation between a vestibular schwannoma and a mere cochlear hearing disorder with only the help of CLS and DPOAE I/O-functions is not possible. The results corroborate the thesis of an additional cochlear component even in small vestibular schwannoma. The implementation of CLS to determine cochlear deficits linked to vestibular schwannoma seems to be medically sensible if the tumor size exceeds 5 mm. According to the diagnostic method used to determine vestibular schwannoma MRI remains the first choice procedure.

Latency-intensity function of speech evoked auditory brainstem responses in individuals with moderate sensory neural hearing loss

Introduction: Compared to click evoked auditory brainstem response (ABR), speech evoked ABR holds an additional advantage by providing information on neural encoding of speech sounds. There is limited data available on speech ABR, both in normal and pathological ears. Aim: The present study focused on finding the latency‑intensity function of speech evoked ABR in moderate sensorineural hearing loss (SNHL). Materials and Methods: Speech ABR was done using the standardized protocol on 13 ears with moderate SNHL were chosen from 20 participants. Results: Speech ABR recording on these ears produced V Peak till 60 dBnHL which was at the level of 10 dBSL. Results showed that the absolute latency of V Peak at the threshold level, that is, at 60 dBnHL was found to be 8.11 ms; 6.68 ms at 70 dBnHL; 5.96 ms at 80 dBnHL; and 5.41 ms at 90 dBnHL. Conclusion: It can be concluded that using speech as a stimulus in evoked responses, it can result in better estimation of loudness growth pattern in individuals with cochlear pathology. A phenomenon like recruitment can be explored in detail as it gives different results in comparison to click or tone evoked responses.

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.