Loudness Tolerance Research Articles

The Hearing of Erastus "Deaf" Smith, Hero of the Texas Revolution.

To describe the speech and hearing abilities of Erastus "Deaf" Smith, the first Texas Ranger, and speculate on the etiology of his hearing loss. Review of credible historical data of what Erastus could and could not hear, descriptions of his voice, and loudness tolerance. Modern analysis of acoustical physics data generated by 0.69-inch diameter non-spinning musket balls. The onset of Erastus' bilateral hearing loss was early childhood. He could hear some. He was intolerant of very loud sounds. His speech was "weak", "squeaky" and high-pitched. He did not use manual communication. He could not hear musket balls passing near his head. The frequency of sound generated by flying 0.69-inch diameter musket balls has been determined as predominantly in the range of 2000-2500 Hz. In contrast to most bilateral childhood sensorineural hearing losses that are worse in high and mid frequencies, Erastus' hearing loss was worse in the low and mid frequencies - preserving at least some high-frequency hearing. Erastus' reverse-slope hearing problem may well have been attributable to incomplete partition type III. If you can't hear it, you can't speak it. NA Laryngoscope, 134:3532-3536, 2024.

Transient decrease in sound tolerance levels following hearing deprivation in normal-hearing subjects

ObjectiveTo determine the circadian influence on sound sensitivity produced by temporal hearing deprivation in healthy normal human subjects. DesignParticipants underwent bilateral earplugging before completion of anthropometry, the author's developed questionnaire, the Hamilton Anxiety and Depression Inventory, pure tone audiometry (PTA), stapedial reflex thresholds (SRT), distortion products otoacoustic emissions input/output (DPOAE-I/O), and uncomfortable loudness levels (ULLs). Afterward, the participants were randomly divided into group A, starting at 8:00 a.m. and finishing at 8:00 p.m., and group B, starting at 4:00 p.m. and ending at 4:00 a.m. Serum cortisol levels and audiological test results were obtained at the beginning and end of the session and 24-h free urinary cortisol levels were measured. Study sampleThirty healthy volunteers. ResultsPTA was 2.68 and 3.33 dB HL in groups A and B, respectively, with no statistical difference between them. ULLs were significantly lower in group A compared to group B, with an average of 8.1 dB SPL in group A and 3.3 dB SPL in group B (p < 0.0001). A SRT shift was observed in group A, with no difference in group B, and a night shift in DPOAE-I/O in group B. ConclusionsReduced loudness tolerance is demonstrated during daytime hearing deprivation in contrast to nighttime; this may be due to increased central gain in the awake cortex.

Maximum acceptable level for the determination of ECAP and ESRT in a paediatric population

Objectives Two of the most used objective measures are electrically evoked action potentials (ECAPs) and electrically evoked stapedius reflex thresholds (ESRTs). Although stimuli used for these measures differ considerably, both measures are influenced by subjective loudness percept. We focus on the subjective maximum acceptable loudness (MAL) to investigate if loudness sensitivity varied along the electrode array during ECAP recordings. In addition, we explored how the MAL reached during an ECAP recording related to the postoperative ESRT. Methods Uni- and bilaterally implanted young CI users (n = 15, average age = 9 y, age range 3–18 y) underwent ECAP and ESR recordings using the clinical software MAESTRO (MED-EL, Innsbruck, Austria) and a commercially available immittance instrument (PATH MEDICAL GmbH, Germering, Germany). Results Loudness tolerance during ECAP recordings was lowest at the two apical-most electrode contacts (number 1 and 2). There was a moderate correlation between the MAL achieved during ECAP recordings and ESR maximum stimulation amplitudes. (r: 0.44344). Conclusions ECAP recordings should commence at basal or medial contacts to increase the users’ comfort and loudness tolerance, especially in young CI users. A higher maximum stimulation appears to increase the chance of the automatic determination of ECAP thresholds for all electrode contacts.

Stapedial reflex threshold predicts individual loudness tolerance for people with autistic spectrum disorders

People with autism spectrum disorder (ASD) frequently show the symptoms of oversensitivity to sound (hyperacusis). Although the previous studies have investigated methods for quantifying hyperacusis in ASD, appropriate physiological signs for quantifying hyperacusis in ASD remain poorly understood. Here, we investigated the relationship of loudness tolerance with the threshold of the stapedial reflex and with contralateral suppression of the distortion product otoacoustic emissions, which has been suggested to be related to hyperacusis in people without ASD. We tested an ASD group and a neurotypical group. The results revealed that only the stapedial reflex threshold was significantly correlated with loudness tolerance in both groups. In addition to reduced loudness tolerance, people with lower stapedial reflex thresholds also exhibited higher scores on the Social Responsiveness Scale-2.

Tinnitus and Auditory Perception After a History of Noise Exposure: Relationship to Auditory Brainstem Response Measures.

To determine whether auditory brainstem response (ABR) wave I amplitude is associated with measures of auditory perception in young people with normal distortion product otoacoustic emissions (DPOAEs) and varying levels of noise exposure history. Tinnitus, loudness tolerance, and speech perception ability were measured in 31 young military Veterans and 43 non-Veterans (19 to 35 years of age) with normal pure-tone thresholds and DPOAEs. Speech perception was evaluated in quiet using Northwestern University Auditory Test (NU-6) word lists and in background noise using the words in noise (WIN) test. Loudness discomfort levels were measured using 1-, 3-, 4-, and 6-kHz pulsed pure tones. DPOAEs and ABRs were collected in each participant to assess outer hair cell and auditory nerve function. The probability of reporting tinnitus in this sample increased by a factor of 2.0 per 0.1 µV decrease in ABR wave I amplitude (95% Bayesian confidence interval, 1.1 to 5.0) for males and by a factor of 2.2 (95% confidence interval, 1.0 to 6.4) for females after adjusting for sex and DPOAE levels. Similar results were obtained in an alternate model adjusted for pure-tone thresholds in addition to sex and DPOAE levels. No apparent relationship was found between wave I amplitude and either loudness tolerance or speech perception in quiet or noise. Reduced ABR wave I amplitude was associated with an increased risk of tinnitus, even after adjusting for DPOAEs and sex. In contrast, wave III and V amplitudes had little effect on tinnitus risk. This suggests that changes in peripheral input at the level of the inner hair cell or auditory nerve may lead to increases in central gain that give rise to the perception of tinnitus. Although the extent of synaptopathy in the study participants cannot be measured directly, these findings are consistent with the prediction that tinnitus may be a perceptual consequence of cochlear synaptopathy.

Early age noise exposure increases loudness perception - A novel animal model of hyperacusis

The neural mechanisms that give rise to hyperacusis, a reduction in loudness tolerance, are largely unknown. Some reports suggest that hyperacusis is linked to childhood hearing loss. However, the evidence for this is largely circumstantial. In order to rigorously test this hypothesis, we studied loudness changes in rats caused by intense noise exposure (12 kHz narrow band noise, 115 dB SPL, 4 h) at postnatal 16 days. Rats without noise exposure were used as controls. The exposed noise group (n = 7) showed a mean 40–50 dB hearing loss compared to the control group (n = 8) at high frequencies (>= 8 kHz) and less hearing loss at lower frequencies. Loudness was evaluated using sound reaction time and loudness response functions in an operant conditioning-based behavioral task using narrow-band noise (40–110 dB SPL, centered at 2, 4 and 12 kHz). Interestingly, the sound reaction time of the noise group was significantly shorter than the control group at supra-threshold levels. The average reaction time was less than 100 ms in the noise group at 100 dB SPL, which was three times shorter than the control group. Our results indicate that early noise-induced hearing loss leads to a significant increase of loudness, a behavior indicative of hyperacusis. Our results are consistent with clinical reports suggesting that hearing loss at an early age is a significant risk factor for hyperacusis.

Comparing Loudness Tolerance and Acceptable Noise Level in Listeners With Hearing Loss.

The present study was a follow-up investigation to a previous study exploring the relationship between listeners' loudness tolerance and listeners' acceptable noise level among normally hearing adults. The present study compared the same two measures, but data were obtained from listeners with hearing loss; 12 adults with sensorineural hearing loss participated in a loudness tolerance measure using a scaling technique initially established for setting hearing aid output limits, in addition to an acceptable noise level measure. The acceptable noise level procedure used in this study quantified the listeners' acceptance of background noise while listening to speech. As with the research involving listeners with normal hearing, the Pearson correlation procedure indicated a lack of any statistically significant correlation between the two measures.

Hyperacusis: An Overview

Hyperacusis (decreased sound tolerance) can be extremely troublesome for affected individuals and their families. Many terms are used to describe sound tolerance symptoms in the clinical literature, and this has led to some confusion. There are associations between hyperacusis and otologic, developmental, neurological, and psychological disorders, and these are described. Work is underway regarding physiological mechanisms, with an increase in central auditory gain an area of interest, but this work is emergent at present. There is a clinical association between hyperacusis and tinnitus, with 40% of persons with troublesome tinnitus also experiencing decreased sound tolerance, but causality is not yet understood. The evaluation of a patient with hyperacusis involves a careful history and a cautious approach to audiological investigation, particularly regarding assessment of loudness tolerance. Questionnaire instruments exist for the assessment of hyperacusis, but none are designed for use with children. Many unanswered questions about decreased sound tolerance exist, and some of these are described.

Relationship between Loudness Tolerance and the Acceptance of Background Noise for Young Adults with Normal Hearing

This study investigated the relationship between listener loudness tolerance and listener acceptable noise level (ANL). Twenty-five normal hearing adults completed loudness tolerance and acceptable noise level measures. Loudness tolerance was measured using a scaling technique. The acceptable noise levels were calculated from a procedure designed to quantify a listener's willingness to accept background noise while listening to speech. Pearson correlation confirmed that loudness tolerance and acceptable noise levels are not related.

Effect of Maximum Power Output and Noise Reduction on Speech Recognition in Noise

The maximum power output (MPO) of a hearing aid was typically discussed in the context of avoiding loudness discomfort. However, an MPO that is too low, as in the cases to avoid discomfort for people with a severe loudness tolerance problem and hearing losses that exceed the fitting range of the hearing aids, could negatively affect sound quality and speech intelligibility in noise. The current study was designed to demonstrate the degradation in speech intelligibility in noise on the HINT (Hearing in Noise Test) when the MPO of the wearers' hearing aids was lowered by 10 dB from the default. The interactions with noise reduction (NR) algorithms (classic [NR-classic] and Speech Enhancer [NR-SE]) were also examined. A single-blinded, factorial repeated-measures design was used to study the effect of noise input level (68 dBC, 75 dBC), MPO setting (default and default-10), and NR algorithm (off, classic, SE) on HINT performance. Eleven adults with a severe sensorineural hearing loss participated. Participants were fit with the Widex m4-19 behind-the-ear hearing aids binaurally in the default frequency response and MPO settings. The hearing aids were adjusted to six MPO (default, default-10) by NR (off, classic, SE conditions). Testing was completed within one 2 hr session. The RTS (reception threshold for speech) for 50% correct on the HINT was measured in each of the six hearing aid conditions at two input levels (68 and 75 dBC) with speech and noise stimuli presented from the front. Repeated-measures ANOVAs were conducted using SPSS software to examine significant differences. A repeated-measures ANOVA showed that noise level was not significant while NR algorithm and MPO were significant. The interaction between noise level and NR algorithm was also significant. Post hoc analysis with Bonferroni adjustment for the effect of NR algorithm showed that performance with NR-off was significantly poorer than performance with NR-classic and NR-SE (p < 0.05). However, NR-classic and NR-SE were not significantly different from each other (p > 0.05). An MPO that was 10 dB lower than the default could negatively affect the signal-to-noise ratio (SNR) of the listening environment. However, NR could compensate for the degradation in SNR.

The Association Between Tinnitus and Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) affects nearly 10% of the population, a prevalence comparable with that of tinnitus. Similarities between the way PTSD and tinnitus influence auditory behaviors include exaggerated startle responses and decreased loudness tolerance. Tinnitus loudness is often exacerbated by sounds that trigger PTSD-related anxiety. This report addresses physical and psychological relations between PTSD and tinnitus. A chart review of veterans seen over a 4-year period for tinnitus services was conducted. Case history and self-assessments of tinnitus handicap were examined in all patients. A review of the literature related to triggers and effects of PTSD was conducted to explore potential consequences related to the presence of PTSD in the Veterans Affairs Medical Center (VAMC) tinnitus population. Chart review confirmed that 34% of the first 300 patients enrolled in the VAMC Tinnitus Clinic also carried a diagnosis of PTSD. Patient reports citing tinnitus severity, suddenness of tinnitus onset, sound-tolerance problems, and sound-triggered exacerbation of tinnitus were more common for patients with a PTSD diagnosis than patients with tinnitus only. Several neural mechanisms linked to both tinnitus and PTSD affect auditory behaviors. Audiologists should be aware that patients with tinnitus and PTSD will require test protocols and referrals that address these powerful responses.

Hyperacusis: Testing, Treatments and a Possible Mechanism

Hyperacusis is a well known phenomenon consisting of a collapse of loudness tolerance. The following generalisations can be made: (1) Hyperacusis is not heightened hearing sensitivity (hearing thresholds are not better than normal); (2) hyperacusis is often accompanied by tinnitus; (3) the severity of hyperacusis is usually inversely proportional to the pitch of the offending noise; (4) perhaps most important, overprotection of the ears is a natural reaction of hyperacusic patients but it must be avoided as it progressively exacerbates hyperacusis. A testing procedure, which involves determining loudness discomfort levels at a number if frequencies, will be described and typical data will be presented. Successful treatment for hyperacusis involves two components: First, training patients to use sound level meters to distinguish between truly damaging sound levels versus those which simply sound too loud; and second, instructing them in the use of a desensitisation program which involves listening to pink noise for several hours daily, starting at a low sound level and progressively increasing it over a period of several months. A new type of protective hearing device will also be described which allows the wearer to avoid loud sounds while preventing over-protection of the ears. When using the device, known as the Star 2001, hyperacusis patients are able to go out and about without fear of encountering loud sounds.The theoretical basis for hyperacusis is not yet known but a potential neural mechanism will be discussed.

Are clinical measurements of uncomfortable loudness levels a valid indicator of real-world auditory discomfort?

A recent study revealed that most patients were wearing National Health Service hearing aids that were capable of exceeding their uncomfortable loudness level (ULL) measured clinically (Munro et al., 1996). However, there is little evidence to show that these clinical measurements are a valid indicator of real-world auditory discomfort. The aim of this study was to investigate the relationship between ULL and real-world discomfort. The study involved 20 adult subjects, aged 41-92 years, who had been fitted monaurally with an NHS hearing aid. ULLs were measured using a probe-tube microphone situated close to the eardrum. Individual real ear to coupler differences were added to the SSPL90 in order to predict the maximum power output (MPO) of the hearing aid at the eardrum. Subjects completed a questionnaire designed to rate the loudness of different environmental sounds. The results show that the more the MPO value exceeded the ULL value, the more likely it was that the subjects reported loudness tolerance problems to environmental sounds of long duration. There was a statistically significant correlation between the ULL and discomfort ratings for sounds of longer duration, such as traffic and wind noise; but not for shorter-duration sounds, such as door banging. Subjects did not express real-world auditory discomfort when the MPO value matched the ULL value. These findings support the argument for setting hearing-aid MPO close to ULL.

The Efficacy of Auditory Integration Training

The present study evaluates the efficacy of auditory integration training (AIT) in a population with multiple handicaps using a double blind experimental design. Thirty residents of a habilitation institute who had multiple handicaps received AIT over a 10-day period. Changes in hearing sensitivity and loudness tolerance, as measured audiometrically, and behavior, as measured by the Aberrant Behavior Checklist (ABC), were evaluated at discrete intervals from 1 week to 9 months post-AIT. Post-AIT data were then compared to pre-AIT data to determine if changes occurred in either hearing or behavior that could be attributed to the experimental stimulus (AIT). We found no significant difference in hearing threshold or loudness tolerance following AIT. Slight improvement in behavior was seen in both the treatment group and the control group, suggesting that factors other than AIT were responsible for behavioral improvement.

Selecting the gain for radio microphone (FM) systems: theoretical considerations and practical limitations.

This paper provides theoretical estimates of the signal-to-noise (S/N) ratio advantage that can be gained from a radio microphone (FM) system used with an environmental (EV) microphone, compared with the S/N ratio delivered by a conventional hearing aid alone. These estimates show that the S/N advantage gained is a function of the speaker/listener distance and the FM/EV gain difference, the greater the distance and the closer the FM gain is to the EV gain, the greater the S/N advantage. The implications for choice of FM and EV gain when fitting FM systems are discussed. The two goals of equating the FM and EV outputs and maximizing the S/N ratio are mutually incompatible. It is concluded that the FM gain should be set to be 10dB less than the EV gain unless the situation can be closely monitored, in which case the FM gain should be set as high as possible consistent with loudness tolerance and acceptable levels of distortion.

Speech identification under simulated hearing-aid frequency response characteristics in relation to sensitivity, frequency resolution, and temporal resolution.

Word identification in noise was measured adaptively under flat and rising frequency response conditions to represent basic alternatives for a hearing-aid characteristic. The speech test results were compared with measures of sensitivity, loudness tolerance, frequency resolution, and temporal resolution in 23 hearing-aid users with mild or moderate sensorineural hearing losses. Subjects also rated the two frequency responses for preference and subjective quality. A paradoxical relationship was found whereby superior speech performance under the flat condition was associated with preference for the rising condition, and vice versa. No combinations of psychoacoustic variables satisfactorily explained either relative performance or preference, although high-frequency sensitivity and upward spread of masking were implicated. Absolute speech performance was related to sensitivity at 2 kHz, age, and sex, but not to frequency resolution once other factors were partialed. Temporal resolution was also a factor, but this was due largely to the influence of extreme values in two subjects. It is concluded that, for moderate degrees of hearing loss, speech identification in noise can be predicted from age, sex, and sensitivity with little advantage from recourse to measurement of frequency or temporal resolution.

Relations between the discomfort level and the reflex threshold of the middle ear muscles.

The reflex threshold of the stapedius muscle is normally 10-20 dB lower than the limit of discomfort. Both depend upon the intensity of the internal ear stimulation. On this are based the monaural objective recruitment test by impedance measurement as well as the subjective loudness tolerance test. After prolonged sound exposure, however, both supraliminal thresholds behave differently: In persons regularly exposed to industrial noise the limit of discomfort is generally found to be shifted to considerably higher sound levels, while the reflex threshold remains normal or is only slightly raised, even in the frequency range of larger hearing losses. Experimental sound exposure in normal-hearing persons unaccustomed to industrial noise suggest the same. Hence, we have to conclude that the higher sound tolerance of workers accustomed to noise is due only to a process of central adaptation, and not to habituation of the internal ear, as has been repeatedly postulated in the present literature on industrial me...

Loudness discomfort level modification.

Three assumptions involved in the rationale for loudness tolerance modification were investigated: (1) that an abnormal loudness discomfort level (LDL) is modifiable by sub-LDL stimulation, (2) that a relationship exists between abnormal LDL and reduced speech discrimination ability, and (3) that an improved LDL will result in better speech discrimination than evidenced before such modification. Twenty subjects with functional evidence of bilateral cochlear hearing loss were divided into four group. Each of three groups received a different type of sound exposure and the other groups served as a control. LDLs were determined before, interjacent to, and after exposure. No significant changes in LDL were found for any of the experimental groups. The parabolic articulation function associated in the literature with monaural cochlear lesions was absent for all cases. Sub-LDL exposure to high intensity speech does not appear to be an effective modifier of an abnormal LDL. The rationale for loudness discomfort level modification therapy, namely to improve speech discrimination, appears to be unwarranted. Abnormal loudness discomfort improvement may involve adjustment problems more responsive to behavioral modification approaches.