Tone Decay Research Articles

Tone Decay Reconsidered: Preliminary Results of a Prospective Study in Hearing-Aid Users with Moderate to Severe Hearing Loss.

Among hearing aid (HA) users, there is a considerable variability in word recognition scores (WRSs). This variability is most pronounced among individuals with moderately severe to severe hearing loss. The variability cannot be adequately explained by factors such as pure-tone audiogram, audiogram type or age. This prospective study was designed to investigate the relationship between tone decay (TD) and WRS in a group of HA users with corresponding pure-tone hearing loss. The study population included 22 patients with hearing loss between 50 and 80 dB HL. Aided WRS, unaided WRS and TD were assessed for both ears. TD was found to be frequency-dependent. TD and WRS were correlated, with up to R = -0.66. The TD test was revealed to be a feasible method for explaining variability in WRS among HA users with hearing loss below 80 dB. This may contribute to improved differential diagnostics. The TD test may thus offer a better understanding of the limitations of HA use in the context of cochlear implant candidacy assessment for HA users.

Wood for guitars II : How the material properties of a spruce guitar top influence the tonal quality of the guitar

Pacific Rim Tonewoods is the world’s largest supplier of spruce tonewood for the soundboard and bracing of the acoustic guitar. A previous study from our research group (JASA 2019) has demonstrated the importance of (1) longitudinal Young’s Modulus and (2) density of the spruce soundboard on the tonal quality of steel string guitars. This study used pairwise comparisons of listener preference to rank a particular guitar model (the Taylor 814ce). The present study updates this previous work, adding a third material property: internal friction (damping) of the soundboard, as measured by the logarithmic decrement of the resonating spruce billet. In addition, objective data on tonal quality were measured on guitars recorded in an anechoic chamber at the Technical University of Dresden, Germany. Spectral sequence analysis, transfer function, and tone decay were measured, and are correlated with the perceptual data. With these data, we can demonstrate the relative importance of the three material properties on the “performance factors” of guitar quality, such as volume, responsiveness, timbre, attack, and sustain. In doing so, we hope to provide the lutherie community with a predictable means of integrating tonewood material properties into their designs, in order to consistently produce their desired tonal outcomes.

Prevalence Rate of Hearing Loss in Patients with Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a common chronic inflammatory disorder that can be associated with some hearing impairments. Hence, we aimed to evaluate the prevalence rate of hearing loss (HL) in RA patients. This study included 130 participants from February 2019 to March 2020 including 100 RA patients (78 females and 22 males) as RA group and 30 healthy cases (16 females and 14 males) as control group. All patients underwent pure tone audiometry, speech audiometry, tympanometry, acoustic reflex, and tone decay test by single operator and device. The rate of HL and contributing factors were then determined. The mean age of RA group was 53.95 ± 7.6 years, and the mean duration of disease was 12.74 years. Rheumatoid factor was positive in 54% of patients, and the frequency rates of diabetes, chronic kidney disease, hypertension, and dyslipidemia among RA patients were 14%, 1%, 26%, and 19%, respectively. These values among RA patients with HL were 18%, 1.7%, 34%, and 27.5%, respectively. HL in RA patients was related to dyslipidemia (P = 0.011) and age (P = 0.0001). Frequency rate of conductive HL in left and right ears was 2% and 5%, respectively, and these rates for sensorineural hearing loss (SNHL) were 55% and 61%, respectively. In addition, the percent of HL in low, mid, and high frequency ranges was 18%, 19%, and 57%, respectively. The findings of the present research demonstrate that HL especially with SNHL and high-frequency types is common among RA patients.

Audiology Lab Tertiary Center

Background: The role of audiology lab and field of audiology in India has expanded exponentially in recent years. However, little is known about the practice trends. The audits allow for changes in service quality to be charted over time both locally and nationally. Audit covers how audiology services should gather information about their service and use that information to improve things for service users. However, such information is currently lacking in India. For this reason, the current audit study is aimed at understanding current audiological practices in India with an intention of identifying areas warranting change. It is important to evaluate our practice trends to identify gaps in services to track quality of practices and possibly in the planning of future services. The current study provides some understanding about the status of current audiological practices in India. This study reports the results of a retrospective audit, which, to our knowledge, is the first of its kind to be conducted in India in the field of audiology. Aims and Objectives: An audit of audiology services at Department of Otorhinolaryngology, AIIMS, Rishikesh. for a period of 5 years (January 2015–December 2019) was conducted to – know number of various types of audiological tests done and to analyse various audiological tests in relation to time spent in minutes/hours per year on individual tests and percentage of average working audiology lab time spent on that particular tests per year to know the ratio of time spent on various audiological tests. Materials and Methods: An observational, retrospective study was conducted as audit of audiology services at Department of Otorhinolaryngology, AIIMS, Rishikesh. for a period of 5 years (January 2015–December 2019). Results: A total of 41,299 audiological investigations were performed during the period of study, i.e., 5 years and it was observed that the most common investigation performed was PTA (20,361; 49.38%), followed by immittance audiometry (10,900; 26.39%), OAE (4306; 10.44%), speech audiometry (2824; 6.84%), special tests (tone decay, SISI, etc.) (1693; 5.0%), and ABR/ASSR (1145; 2.77%). The most commonly performed audiological test was PTA (49.38%), and an average time spent on PTA (at 20 min per test) was 81,440 min/1357.33 h, i.e., 73.44% of total working time of audiology lab per year. (1,10,880 min/1848 h) followed by Immittance audiometry (26.39%), and an average time spent on immittance audiometry (at 10 min per test) was 21,800 min/363.33 h, i.e., 19.66% of total working time of audiology lab per year. (110,880 min/1848 h). Conclusion: The current study provides useful information about the diversity in current audiological practices in India. This study identifies the need for improving clinical practice, as inconsistencies were observed even in performing basic procedures such as PTA. This could greatly improve audiological practice and, thereby, patient outcomes. As per advances in audiology, this study can contribute in planning Telepractice in Audiology: Future Prospects and Challenges.

CARLOS POTENCIANO REYES, MD (1940 - 2020) Little-Known but Significant Pioneer

Consultants and more senior co-resident physicians at the Philippine General Hospital (PGH) would call him “Caloy.” Hardly would I hear anybody (including our ENT department secretary) address him as Dr. Reyes. This was not because he was not a respected faculty member. Rather, he was everybody’s friend and he probably preferred to be addressed by his nickname.
 Dr. Carlos P. Reyes was a tall, friendly guy, easily recognizable while walking through the short PGH corridor stretching from the old ENT Ward (Ward 3) to the old ENT operating room (OR) called Floor 15, later designated as the PGH Nursing Office. He would almost always be holding either an expensive photography camera, electronic gadget, ENT OR instrument, or car magazines – suggesting his varied interests aside from having good knowledge of Otolaryngology, particularly Otology. He would usually stop and chat with an acquaintance about his new medical or non-medical interests.
 I first met Dr. Caloy when I was the first year resident assigned to the Otology section. He would call me “Ging” while presenting the ear patients at the outpatient department (OPD) Ear Clinic, only to learn later that he would address all unfamiliar persons by that name. He was kind, helpful and very understanding. Equipped with ample information in Otology he gathered from postgraduate studies abroad, he would selflessly share these with the residents in order to sharpen our diagnostic acumen. He would instruct us to rely on concise yet complete clinical examination, involving audiologic evaluation tools and meager radiologic information in considering differential diagnoses. He was quite willing to assist us in our learning processes, particularly on how to distinguish middle ear from inner ear disorders, and cochlear versus retrocochlear diseases. Since we did not have any audiologist at that time, he admonished us to carry out the needed audiometric evaluations on our ear patients ourselves in order to learn both the techniques of the procedures and their limitations. Hence, after the OPD clinic we would not only perform routine pure tone and speech audiometric tests but also special examinations like the Bekesy test, short increment sensitivity index (SISI) test, alternate binaural loudness balance (ABLB) test and the test for tone decay. We would then discuss the test results during our next ear clinic and we would listen and be amazed at how Dr. Caloy would integrate the information and arrive at the complex diagnosis.
 Dr. Caloy was our mentor at the time when refinements in tympanoplasty and mastoidectomy aroused the excitement and imagination of budding otologists worldwide. Whereas canal down mastoidectomy was the usual norm to safely remove common mastoid pathology like cholesteatoma, Dr. Caloy introduced the concept of intact canal wall mastoidectomy that avoids or mitigates recurrent postoperative cleaning of the mastoid bone. The period was also the dawn of neuro-otology when Dr. William House popularized the transmastoid approach for acoustic neuroma and the endolymphatic mastoid shunt as treatment for Meniere’s disease. In order to teach us the anatomical and surgical principles of performing these procedures, Dr. Caloy set up the first temporal bone dissection laboratory in the country at the mezzanine above the ENT conference room. He would offer the course to all ENT residents-in-training and consultants nationwide. He practically revolutionized the method of otologic surgery by requiring ENT surgeons to practice doing ear surgery in the temporal bone dissection lab prior to performing ear surgeries in the operating room. In addition, he advocated the use of the operating microscope and dental drills in place of the old bone gouges, chisels and bone ronguers. His ideas were later adopted by other ENT training institutions as we see today. The requirement that every ENT resident must undergo temporal bone dissection in the course of his training obviously stemmed from the efforts of Dr. Caloy. Many senior ENT consultants who are still with us today were former students of Dr. Caloy in his temporal bone lab
 Unfortunately, before finishing my residency training, Dr Caloy expeditiously left the PGH ENT department for unknown reasons. He then set up his private clinic in Quezon City and later joined the ENT department of University of Santo Tomas.
 Reflecting on the significant yet probably unknown achievements of Dr. Caloy toward the advancement of otology and neuro-otology in our country, I realize how blessed I was to be one of his students during that brief period when he was still with us at UP-PGH.
 With our profound gratitude Sir, we will always remember you.

A study on the outcome of various methods of administration of intratympanic dexamethasone in tinnitus of cochlear pathology

<p class="abstract"><strong>Background:</strong> The aim of the study was to compare the outcome of various methods of injecting intra tympanic steroids in patients with tinnitus of cochlear pathology.</p><p class="abstract"><strong>Methods:</strong> A prospective study was conducted on 56 patients with subjective tinnitus of cochlear pathology who were then divided into three groups. After thorough otological and audiological evaluation using standard questionnaire, ENT examination, pure tone audiometry, tone decay test, tinnitogram, CT scans of temporal bone and brain. Each patient underwent one of the three chosen methods of intra tympanic steroids administration randomly. The methods are 1-Tympanomeatal flap elevationand application of steroid soaked gelfoam sponge; 2-Transtympanic steroid injection; 3-Grommet insertion followed by steroid administration. These methods were performed for subjects with tinnitus of cochlear pathology from 2009 to 2011 at a neurotological clinic at Chennai. After following up on 1st, 3rd and 6 months the observations were statistically analysed. </p><p class="abstract"><strong>Results:</strong> Success rate for techniques viz tympanomeatal flap was 70%, transtympanic - 63%, grommet - 50%. But when comparing statistically all the three methods were equally successful.</p><p class="abstract"><strong>Conclusions:</strong> Intratympanic steroids for tinnitus (cochlear pathology) are a safe, simple and promising treatment option. Though all the methods of intra tympanic steroids injection had similar success rate, the tympanomeatal flap elevation method may be preferred since it can be done in a single sitting. However transtympanic injection remains the easiest and cost effective compared to the other two methods.</p>

Assessing auditory nerve condition by tone decay in deaf subjects with a cochlear implant

The condition of the auditory nerve is a factor determining hearing performance of cochlear implant (CI) recipients. Abnormal loudness adaptation is associated with poor auditory nerve survival. We examined which stimulus conditions are suitable for tone decay measurements to differentiate between CI recipients with respect to their speech perception. Tone decay was defined here as occurring when the percept disappears before the stimulus stops. We measured the duration of the percept of a 60-s pulse train. Current levels ranged from below threshold up to maximum acceptable loudness, pulse rates from 250 to 5000 pulses/s, and duty cycles (percentages of time the burst of pulses is on) from 10% to 100%. Ten adult CI recipients were included: seven with good and three with poor speech perception. Largest differences among the subjects were found at 5000 pulses/s and 100% duty cycle. The well performing subjects had a continuous percept of the 60-s stimulus within 3 dB above threshold. Two poorly performing subjects showed abnormal loudness adaptation, that is, no continuous percept even at levels greater than 6 dB above threshold. We conclude that abnormal loudness adaptation can be detected via an electric tone decay test using a high pulse rate and 100% duty cycle.

Correlations Between the Degree of Endolymphatic Hydrops and Symptoms and Audiological Test Results in Patients With Menière's Disease: A Reevaluation.

This study was performed to reevaluate the diagnostic significance of clinically well-accepted audiological tests in indicating endolymphatic hydrops (EH) in Menière's disease (MD). Retrospective case review. Hospital. Fifty patients (52 affected ears) diagnosed with MD were enrolled. Diagnostic. To analyze the correlations between endolymphatic hydrops and results of audiological test including the pure-tone audiometry threshold, suprathreshold function tests, electrocochleogram, and glycerol test. Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging demonstrated EH in either the vestibule or cochlea to various degrees in all of the MD patients, 24 hours after intratympanic gadolinium chelate injection. Both vestibular and cochlear EH were significantly correlated with PTA threshold. However, EH was not associated with alternate binaural loudness balance or the tone decay test, although a correlation was observed with the short-increment sensitivity index. There was also a correlation between vestibular EH, but not cochlear EH, and the negative summating potential/action potential (-SP/AP) ratio. Neither vestibular EH nor cochlear EH was correlated with the glycerol test results. In addition, the frequency of vertigo attacks, the existence of tinnitus, and aural fullness did not correlate with EH. Disrupted ionic homeostasis in the inner ear, but not the EH, may contribute to changes in the -SP/AP ratio. The relevance of glycerol test in identifying EH through detection of hearing changes needs further investigation in the future.

Subjective and Objective Estimate of Neural Fatigue in an Adult with Auditory Neuropathy Spectrum Disorder

Auditory neuropathy spectrum disorder (ANSD) is a retrocochlear disorder in which cochlear functioning is normal but the transmission in the auditory neural pathway is affected. The present study reports of neural fatigue seen in subjective and objective tests of adaption in a 19 year old adult with ANSD. He had bilateral mild sensorineural hearing loss with otoacoustic emissions present and absent auditory brainstem response. Immittance evaluation showed elevated acoustic reflexes at 500 Hz and 1000 Hz in both ipsilateral and contralateral stimulation. Reflex decay test was administered at 500 Hz and 1000 Hz which showed positive reflex decay with contralateral stimulation. Olsen and Noffsinger tone decay test and supra-threshold adaptation test showed positive tone decay at 500 Hz, 1000 Hz and 2000 Hz in both ears. The results of the study showed positive reflex decay and positive tone decay which indicate abnormal neural fatigue. The abnormal neural firing seen in individuals with ANSD could have resulted in positive reflex decay and tone decay. However, further studies on larger group of population are essential for further understanding the mechanisms in detail.

Sensorineural Hearing Loss in Non-depressed Essential Tremor Cases and Controls: A Clinical and Audiometric Study.

BackgroundPatients with essential tremor (ET) have an increased prevalence of hearing loss, and depression is a confounding issue for both conditions. We assessed hearing loss in non-depressed ET patients and controls using a questionnaire and audiometric tests.MethodsThe study included 34 patients with ET and 45 volunteers were included. Both groups were asked if they had hearing loss, and pure tone audiometry, speech recognition threshold, tympanogram, short increment sensitivity index (SISI), tone decay, and otoacoustic emission audiological tests were conducted.ResultsSeventeen subjects (50.0%) in the patient group answered “yes” to the question “Do you have hearing loss?” compared to one (2.2%) subject in the control group (p<0.001). The tone decay values of the right ear at 4,000 Hz were higher in the patient group. The number of subjects in which the otoacoustic emissions could not be obtained in the right ear was higher in the ET patients (p = 0.005).DiscussionThe results support the presence of a cochlear pathology in ET and may indicate that ET and sensorineural hearing loss may be components of a common disease process.

Sensorineural Hearing Loss in Non-depressed Essential Tremor Cases and Controls: A Clinical and Audiometric Study

<strong>Background:</strong> Patients with essential tremor (ET) have an increased prevalence of hearing loss, and depression is a confounding issue for both conditions. We assessed hearing loss in non-depressed ET patients and controls using a questionnaire and audiometric tests. <strong>Methods:</strong> The study included 34 patients with ET and 45 volunteers were included. Both groups were asked if they had hearing loss, and pure tone audiometry, speech recognition threshold, tympanogram, short increment sensitivity index (SISI), tone decay, and otoacoustic emission audiological tests were conducted. <strong>Results:</strong> Seventeen subjects (50.0%) in the patient group answered ‘‘yes’’ to the question ‘‘Do you have hearing loss?’’ compared to one (2.2%) subject in the control group (<strong>p&lt;0.001</strong>). The tone decay values of the right ear at 4,000 Hz were higher in the patient group. The number of subjects in which the otoacoustic emissions could not be obtained in the right ear was higher in the ET patients (<strong>p=0.005</strong>). <strong>Discussion:</strong> The results support the presence of a cochlear pathology in ET and may indicate that ET and sensorineural hearing loss may be components of a common disease process.

E024 Demographic factors influencing educational placement of the hearing impaired child with a cochlear implant

This chapter focuses on the practical applications of neuroanatomy for the speech-language pathologist. The brain itself is housed very securely inside the calvarium—skull bone structure—and is separated from the calvarium only by three interwoven membranes that are collectively referred to as the meninges. The outermost meningeal layer lying directly underneath the skull bones is referred to as the dura mater. The major venous drainage systems, such as the superior sagittal and transverse sinuses, lie within the dural folds. For speech-language pathologists, it is routine procedure to refer the individual to an audiologist to perform more accurate audiometric testing to assess the client's acuity to pure tones of different intensities at different frequencies. Additional acoustic procedures are valuable to differentiate certain types of hearing problems. These tests include speech audiometry consisting of speech discrimination scores and speech reception thresholds, binaural loudness balance testing, loudness recruitment testing, auditory adaptation and tone decay testing, Bekesy testing, short increment sensitivity levels testing, middle ear impedance testing, and electrophysiological testing.

Oxford stone revisited: causes and consequences of diversity in building limestone used in the historic centre of Oxford, England

Abstract Stone decay is the result of the interaction of stone with its environment. It is therefore important to understand why certain materials, sometimes not the most suitable, were used to shape the built heritage of specific areas. The historical evolution of these areas conditioned many of the combinations of materials we see today, which in some cases can interact to accelerate decay. These combinations were driven by availability during construction, architectural fashion or the simultaneous utilization of materials that are aesthetically similar but differ significantly in their physical and chemical properties. A microcosm of the complex decisions that determine stone selection and subsequent interactions is provided by the City of Oxford, which is an excellent example of how such historic evolution can work with material characteristics to accelerate decay.

Analysis of the part-pedaling effect in the piano

This letter reports basic acoustic phenomena related to part-pedaling in the piano. With part-pedaling, the piano tone can be divided into three distinct time intervals: initial free vibration, damper-string interaction, and final free vibration. Varying the distance of the damper from the string, the acoustic signal and the damper acceleration were measured for several piano tones. During the damper-string interaction, the piano tone decay is rapid and the timbre of the tone is affected by the nonlinear amplitude limitation of the string motion. During the final free decay, the string continues to vibrate freely with a lower decay rate.

Hearing Loss in Patients with Rheumatoid Arthritis

Background and Objectives：In patients with rheumatoid arthritis (RA), sensorineural (SN), conductive, and mixed hearing loss (HL) have been reported in increased rates compared with persons without RA. The object of this study was to evaluate the prevalence and type of HL in patients with RA. We also examined the correlation between HL and the clinical data and determined which factors may be involved in the pathogenesis of RA-related HL. Subjects and Method：In this prospective controlled study, we compared 40 RA patients with 40 age and sex-matched controls. All patients underwent rheumatologic evaluation including ESR, CRP, rheumatoid factor, rheumatoid nodule, etc. Audiologic assessment consisting of pure tone, speech, impedence audiometry, and tone decay test was performed. Statistical analysis of the two groups was carried out. Results：The prevalence of the SNHL (air conduction threshold of >30 dB at ≥1 frequency or >25 dB at ≥2 frequencies and both air and bone conduction thresholds within 10 dB of each other) was significantly higher in the RA group (42.5%), and the majority was bilateral and cochlear type. Air conduction threshold at 8,000 Hz differed significantly between the patients and the control group (p< 0.05). Speech and impedence audiometry did not differ in both groups. The presence of SNHL in patients with RA was related to ESR, CRP, patients’ age, and medication such as prednisolone. Conclusion：SNHL of the cochlear type is increased in patients with RA especially at 8,000 Hz. (Korean J Otorhinolaryngol-Head Neck Surg 2009;52:118-23)

Migraine and audiovestibular dysfunction: is there a correlation?

Purpose To study the audiovestibular functions in cases of migraine with or without vertigo. Materials and methods This was a prospective study involving 50 cases of migraine who were divided into 2 groups: patients with vertigo and those without. All patients underwent a detailed otological and neurootological examination followed by full audiological and vestibular investigation including pure tone audiometry, speech reception threshold, speech discrimination score, tone decay, short increment sensitivity index, auditory brainstem-evoked responses, and electronystagmography (ENG). Results Thirty-eight (76%) of 50 patients had vertigo on presentation, of which rotatory nonpositional vertigo (22/38) was the most common. Phonophobia was the most common auditory symptom (35/50, 70%) followed by tinnitus (25/50, 50%). Only 17 patients (34%) reported hearing loss, of whom only 7 had documented hearing loss on pure tone audiometry. However, the auditory brainstem-evoked responses of all these patients showed some abnormalities in the form of prolonged absolute latency or prolonged interwave peak latencies or both. Electronystagmography revealed canal paresis in 13 patients (26%), although there was no statistical difference between patients with or without vertigo on various electronystagmographic parameters. Conclusion Auditory brainstem-evoked response abnormalities may be the earliest indicator of impending auditory involvement in migraine.

The Impact of New Codes for the Evaluation of Central Auditory Function

The Impact of New Codes for the Evaluation of Central Auditory Function

Turning speech into music in a two-dimensional space by varying the bandwidth and rate of tone pulses placed along formant tracks

A two-dimensional space is introduced which changes sounds from speech-like to music-like by varying the rate and the bandwidth (decay-time) of individual tones placed along formant contours. At one extreme of a very fast pulse rate and a long decay time, the sounds are equivalent to sine-wave speech. With a more moderate tone rate and a short decay time, the sounds become monotone (at the tone-rate) speech. For tone rates around 10/s with long decay times, individual musical tones are heard at the formant frequencies. Intelligibility is poor for such sounds because of the low sampling rate of the formant contours. Increasing the tone rate and decreasing tone decay time increases intelligibility and makes the sounds less music like. Intelligibility data together with speech-like and music-like ratings of sounds from this space will be presented.

Neurotological status in Behçet’s disease and its ophthalmological correlates

Objective: To assess neurotological status and its ophthalmological correlates in Behçet’s disease. Study design: A cross sectional study in which 17 patients with Behçet’s disease and 13 healthy controls were...

Tone decay for hearing-impaired listeners with and without dead regions in the cochlea.

For people with normal hearing, a sustained tone with a frequency within the standard audiometric range remains audible when presented at a level well above threshold. However, for a pure tone with frequency close to the upper limit of hearing (well above 8 kHz), the loudness may decrease within seconds and the tone may decay to inaudibility, even when presented at a level between 20 and 40 dB SL. Scharf [in Hearing Research and Theory, edited by J. V. Tobias and E. D. Schubert (Academic, New York, 1983), Vol. 2, pp. 1-53] suggested that marked loudness adaptation only occurs when the excitation pattern evoked by a tone is spatially limited. The upper limit of hearing may be comparable to the boundary of a "dead region," which is a region with a complete loss of inner hair cell (IHC) and/or neural function. The present study investigated the perceived decay of pure tones for 9 normal-hearing subjects and 12 subjects with moderate to severe sensorineural hearing loss, using a wide range of frequencies (0.125-12 kHz). A dead region was diagnosed for 8 of the 12 subjects. No consistent association was found between the degree of tone decay and the presence of a dead region. Subjects with dead regions did not experience significantly more tone decay than subjects with comparable absolute thresholds but without a dead region, even when the frequency of the tone fell within or close to the edge of a dead region. For severely hearing-impaired subjects, spatial restriction of the excitation pattern was neither necessary nor sufficient to lead to tone decay. The prevalence of tone decay was not well predicted by the audiometric threshold at the test frequency. It is proposed that tone decay depends on the physiological condition of the place in the cochlea where the tone is detected, which, in a case involving a dead region, is the place adjacent to the dead region. The prevalence of tone decay increased when the audiometric threshold was above 50 dB HL in the frequency region where the tone was detected.