Probe Tone Research Articles

Middle-ear muscle reflex: Sensitivity and reliability of thresholds and amplitude-intensity functions in normal-hearing adults across measurement systems

Standard clinical middle-ear muscle reflexes (MEMRs) are typically measured as a change in admittance for a single, 226-Hz probe tone in the presence of an eliciting stimulus. Alternatively, wideband MEMRs are measured as a change in reflectance for a wideband click probe in the presence of an elicitor. This study evaluated test-retest measures of MEMR thresholds and amplitude-intensity (A-I) functions across four measurement systems based on differences in sensitivity (i.e., thresholds, A-I slopes) and reliability. Ten normal-hearing adults participated in two sessions. MEMR thresholds and A-I functions were measured using two clinical systems (GSI, Titan) with two elicitors (2 kHz, broadband noise-BBN), and two wideband systems (Titan Research module, Custom Etymotic-based system). The 2-kHz elicitor yielded the highest thresholds overall. BBN elicitors produced similar thresholds across clinical and wideband systems. The broadband elicitor with the clinical systems produced the steepest A-I slopes, and the slopes were steeper overall for clinical versus wideband systems. In most conditions, no significant test-retest differences were observed for thresholds or AI-functions, but intraclass correlations were highest for the clinical system measures. MEMR measures made with current clinical systems using BBN elicitors may optimize sensitivity, reliability, and overall diagnostic value of such measures.

Wideband Tympanometry: Normative Data for Young Iranian Adults

Introduction: The middle ear sound transmission features can impact acoustic sounds reaching the inner ear. Wideband tympanometry (WBT) or wideband acoustic immittance is an effective and desirable measurement of conductive conditions in newborns and adults and has appropriate sensitivity to distinguish different pathologies like otosclerosis from other middle ear conflicts. Recently, there has been an increased utilization of WBT, which highlights the importance of collecting population-based normative data as a necessary step in the standardization of this test, as well as for its clinical application. This study aimed to obtain normative data on WBT in the adult Iranian ethnic. Methods: There were 101 participants (202 ears) consisting of 53 males (57.4%) and 48 females (42.6%) in the age range of 19–29 years. The Titan WBT device (Interacoustics, Assens, Denmark) was used for WBT measurements. The broadband click was utilized as the probe tone between frequencies of 250 Hz and 8,000 Hz. All the participants underwent ear, nose, and throat assessments, pure-tone audiometry, and conventional tympanometry (226 Hz). Features like equivalent ear canal volume (V_eq), tympanometric peak pressure, gradient, resonance frequency (RF), energy absorbance (EA), and admittance (A_d) were tested. Results: In this cross-sectional study, 202 ears were tested for WBT. EA increased by frequency enhancement; at 1 kHz and 2 kHz the EA was the most prominent; at 2,519 Hz, it started decreasing, and at 8 kHz, there was a slight increase. There was also a significant difference in the V_eq and A_d between males and females. Studies have shown that the V_eq may vary between male and female subjects based on body size. Conclusion: In this study, normative data for the WBT were obtained from young Iranian adults with normal hearing ranges and middle ear conditions. We hope that this study and the resulting norm will provide a basis for increasing the use of WBT in Iranian diagnostic and clinical practices.

Configuration of Probe Tones for MKID Readout with Frequency Sweeping Scheme

Configuration of Probe Tones for MKID Readout with Frequency Sweeping Scheme

Wideband Tympanometry in Adults with Severe to Profound Hearing Loss with and without Cochlear Implants

Objectives—Cochlear implantation has been suggested to be associated with an air-bone gap, possibly secondary to increased middle- and inner-ear stiffness. To explore the effect of possible changes in mechanics due to cochlear implantation, we measured wideband tympanometry (WBT) in individuals with normal hearing and individuals with severe to profound sensorineural hearing loss who underwent unilateral or bilateral cochlear implantation. Our goal was to characterize differences in WBT patterns associated with severe to profound sensorineural hearing loss and with cochlear implantation. Design—The study participants were 24 individuals with normal hearing (48 ears) and 17 with cochlear implants, of which 15 were unilaterally implanted and two were implanted bilaterally. All the participants had normal otoscopy. In the implanted group, inner-ear anatomy was normal according to preoperative imaging. All participants underwent pure-tone audiometric assessment, standard tympanometry (226 Hz probe tone), and WBT to a click stimulus (analyzed from 226 to 8000 Hz). WBT was recorded at ambient and peak pressures. To elucidate the effect of sensorineural hearing loss on WBT, we compared normal-hearing ears with impaired non-implanted ears. The impact of cochlear implantation was assessed by comparing the WBT of the implanted and non-implanted ears of the same participants. Moreover, the effect of the ear (right vs. left) and test–retest reproducibility were evaluated. Results—WBT results for right and left ears showed no statistically significant differences in the normal hearing participants. There were no statistical differences shown between repeated measurements of WBT with removal and re-insertion of the probe in any of the groups—the normal ears, the implanted ears, and the non-implanted ears with hearing impairment. Peak compensated admittance (Ytm) in standard tympanometry was normal in 32 out of 34 (94%) ears with sensorineural hearing loss, with one CI user having bilateral negative middle-ear pressure. Compared to normal-hearing ears, ears with severe to profound SNHL, with or without cochlear implantation, showed a significant decrease in absorbance at high frequencies (4000–5000 Hz). Implanted ears, compared both to normal-hearing and contralateral-non-implanted ears, showed a significant decrease in absorbance at low frequencies (400–800 Hz) and an increase in absorbance around 1600 Hz. Conclusions—WBT analysis revealed that the implanted ears showed a significant decrease in absorbance at low frequencies (400–800 Hz) and an increase at 1600 Hz. This finding is likely a result of an increased stiffness due to the implantation surgery and the presence of the implant in the inner ear. In contrast, the specific decrease in absorbance around 4000–5000 Hz in the implanted and non-implanted ears compared to the normal ears is likely either due to aging or the impact of the severe-to-profound SNHL on the input impedance of the cochlea. The structural and functional changes of both the conductive system and the cochlea associated with aging and SNHL may change the wideband acoustic immittance of the ear and these alterations might be correlated with the hearing loss severity. Additional research is needed to determine how much hearing loss and age influence wideband acoustic immittance of the ear.

No Reduction in the 226-Hz Probe Tone Acoustic Reflex Amplitude Following Severe Inner Hair Cell Loss in Chinchillas.

The relationship between the middle ear acoustic reflex (AR) and inner hair cell (IHC) loss is currently unknown. Given that IHC are believed to convey nearly all acoustic information to the central auditory nervous system, it has been assumed that loss of IHC would significantly impact the AR. To evaluate this relationship, we assessed the presence and amplitude of the AR in chinchillas before and after treatment with carboplatin, an anticancer drug that reliably and selectively destroys IHC in this species. Baseline measures of hearing sensitivity, including auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAE), were assessed and then re-evaluated following carboplatin treatment. Post-carboplatin ABR thresholds and DPOAE were found to be unchanged or slightly elevated; results were consistent with published reports. Our main hypothesis was that loss of IHC would abolish the reflex or significantly reduce its amplitude. Contrary to our hypothesis, the ipsilateral 226-Hz AR continued to be reliably elicited following carboplatin treatment. Post-mortem histological analysis confirmed significant IHC loss (65-85 %), but no measurable loss of outer hair cells (OHCs). Given that loss of IHC alone does not significantly reduce the 226-Hz AR, our results suggest that few IHC are needed to maintain the 226-Hz AR response. These results suggest additional studies are needed to better understand the role of IHC in the reflex arc, present opportunities to further study the reflex pathway, and could change how we use the clinical AR as a potential diagnostic tool for IHC dysfunction, including those related to IHC synaptopathy.

Imagined Musical Scale Relationships Decoded from Auditory Cortex.

Notes in a musical scale convey different levels of stability or incompleteness, forming what is known as a tonal hierarchy. Levels of stability conveyed by these scale degrees are partly responsible for generating expectations as a melody proceeds, for emotions deriving from fulfillment (or not) of those expectations, and for judgments of overall melodic well-formedness. These functions can be extracted even during imagined music. We investigated whether patterns of neural activity in fMRI could be used to identify heard and imagined notes, and if patterns associated with heard notes could identify notes that were merely imagined. We presented trained musicians with the beginning of a scale (key and timbre were varied). The next note in the scale was either heard or imagined. A probe tone task assessed sensitivity to the tonal hierarchy, and state and trait measures of imagery were included as predictors. Multivoxel classification yielded above-chance results in primary auditory cortex (Heschl's gyrus) for heard scale-degree decoding. Imagined scale-degree decoding was successful in multiple cortical regions spanning bilateral superior temporal, inferior parietal, precentral, and inferior frontal areas. The right superior temporal gyrus yielded successful cross-decoding of heard-to-imagined scale-degree, indicating a shared pathway between tonal-hierarchy perception and imagery. Decoding in right and left superior temporal gyrus and right inferior frontal gyrus was more successful in people with more differentiated tonal hierarchies and in left inferior frontal gyrus among people with higher self-reported auditory imagery vividness, providing a link between behavioral traits and success of neural decoding. These results point to the neural specificity of imagined auditory experiences-even of such functional knowledge-but also document informative individual differences in the precision of that neural response.

High frequency (1000 Hz) tympanometry in six-month-old infants

ObjectivesHigh frequency tympanometry (HFT) using a 1000 Hz probe tone is recommended for infants from birth to six months of age. However, there is limited normative HFT data outside the newborn period. The objective of this study was to describe HFT data in healthy six-month-old infants. MethodsHFT and distortion product otoacoustic emission (DPOAE) tests were performed on 168 six-month-old full-term healthy infants. Ears that passed DPOAEs and had a single-peaked tympanogram were included for analysis. The tympanometric measures included in the normative HFT data were tympanometric peak pressure (TPP), peak compensated static admittance (Ytm) and tympanometric width (TW). ResultsA total of 118 ears from 118 infants who passed DPOAE and had single-peaked tympanograms were included in the analysis. Normative data were presented for TPP, Ytm and TW. A comparison of the present study with studies on neonates and younger infants revealed significantly higher mean Ytm and lower mean TPP for six-month-old-infants. ConclusionSignificant differences in HFT findings between neonates and six-month-old infants suggest a developmental trend and confirm the need for separate age-appropriate norms for the tympanometric measures. Normative HFT data described in the present study may provide useful information for optimizing the diagnosis of conductive conditions in six-month-old infants.

Evaluation of age-related changes in middle-ear structures by wideband tympanometry

Background Presbycusis is bilateral sensorineural hearing loss associated with the progressive degeneration of cochlear and central auditory pathways with aging. Aims/Objectives We aimed to reveal age-related changes in middle ear function by using wideband tympanometry (WBT). Materials and Methods Fifty-eight patients diagnosed with presbycusis were compared to 52 audiologically healthy participants. WBT measurement was performed on both ears via wideband click stimulus with a tympanometer device using probe tone frequencies of 226–8000 Hz. Results There were no statistically significant differences detected among the resonance frequencies or maximum absorbance ratios measured in both ears between groups (p > .05). The mean absorbance of the right and left ears at 4000 and 8000 Hz was statistically higher in the patient group than in the healthy controls (r = 0.038, 0.030; l = 0.015, 0.012). Moreover, mean compliance values were found to be significantly lower in the patient group than in the control group (r = 0.030 and l = 0.040). Conclusion The significant differences detected in compliance and absorbance values for high frequencies in presbycusis patients were remarkable. Thus, it has been shown that WBT yields an advantage compared to traditional tympanometry in the diagnosis and treatment of middle ear diseases.

Do Picardy Thirds Smile? Tonal Hierarchy and Tonal Valence

Western tonality provides a hierarchy among melodic scale-degrees, from the closural tonic triad notes to “out-of-key” chromatic notes. That hierarchy has been occasionally linked to emotion, with more closural degrees associated with more positive valence. However, systematic investigations of that association are lacking. Here, we examined the associations between tonality and emotion in three experiments, in musicians and in nonmusicians. We used an explicit task, in which participants matched probe tones following key-establishing sequences in major and minor keys to facial expressions ranging from sad to happy, and an implicit speeded task, adapting the Implicit Association Test. More closural scale-degrees were associated with more positive valence in all experiments, for both musicians and nonmusicians, with larger effects for major keys. The pattern of results significantly differed from that observed in a comparable goodness-of-fit task, suggesting that perceived scale-degree valence is not reducible to tonal fit. The comparison between the results from the explicit and implicit measures suggests that tonal valence may rely on two distinct mechanisms, one mediated by conceptual musical knowledge and conscious decisional processes, and the other largely modulated by nonconceptual, involuntary processes. The experimental paradigms introduced here may help mapping additional connotative meanings, both emotional and cross-modal, embedded in tonal structure, thus suggesting how “extra-musical” meanings are conveyed through tonal hierarchy.

The effects of noise exposure and aging on the acoustic reflex in normal-hearing people

Noise exposure and aging can cause subclinical hearing problems that are not identified with conventional audiometry. Nerve damage among the normal hearing could reduce afferent auditory-nerve activity consequently reducing the middle ear muscle reflex (MEMR). It was hypothesized that normal-hearing individuals reporting more noise exposure would have slower growth of MEMR with increasing levels. Data were analyzed from sixty-one young, normal-hearing people. Each completed the four MEMR assessments and the Life-Time Exposure to Noise and Solvents Questionnaire. Reflex amplitudes were measured as a function of sound level using clinical equipment. High-pass noise stimuli (1.5-4.0 kHz) and a 1-KHz tone were used as elicitors with a 226-Hz probe tone. Data were analyzed using a linear mixed effects model. Individuals reporting higher noise exposure with the LENS-Q had significantly reduced growth of MEMR with level, supporting the hypothesis. Independent effects of age and gender were also observed. The effect of the pure-tone average on MEMR growth functions did not reach significance at the 5% level (p = 0.052). No significant relationships were observed between the MEMR measures and extended high-frequency thresholds nor with word recognition in noise. The results suggest that the MEMR could indicate subclinical nerve damage.

Auditory filter shapes derived from forward and simultaneous masking at low frequencies: Implications for human cochlear tuning

Behavioral forward-masking thresholds with a spectrally notched-noise masker and a fixed low-level probe tone have been shown to provide accurate estimates of cochlear tuning. Estimates using simultaneous masking are similar but generally broader, presumably due to nonlinear cochlear suppression effects. So far, estimates with forward masking have been limited to frequencies of 1 kHz and above. This study used spectrally notched noise under forward and simultaneous masking to estimate frequency selectivity between 200 and 1000 Hz for young adult listeners with normal hearing. Estimates of filter tuning at 1000 Hz were in agreement with previous studies. Estimated tuning broadened below 1000 Hz, with the filter quality factor based on the equivalent rectangular bandwidth (QERB) decreasing more rapidly with decreasing frequency than predicted by previous equations, in line with earlier predictions based on otoacoustic-emission latencies. Estimates from simultaneous masking remained broader than those from forward masking by approximately the same ratio. The new data provide a way to compare human cochlear tuning estimates with auditory-nerve tuning curves from other species across most of the auditory frequency range.

An Exploratory Investigation of Pupillometry As a Measure of Tinnitus Intrusiveness on a Test of Auditory Short-Term Memory.

The purpose of the current study was to investigate the potential of pupillometry to provide an objective measure of competition between tinnitus and external sounds during a test of auditory short-term memory. Twelve participants with chronic tinnitus and twelve control participants without tinnitus took part in the study. Pretest sessions used an adaptive method to estimate listeners' frequency discrimination threshold on a test of delayed pitch discrimination for pure tones. Target and probe tones were presented at 72 dB SPL and centered on 750 Hz±2 semitones with an additional jitter of 5 to 20 Hz. Test sessions recorded baseline pupil diameter and task-related pupillary responses (TEPRs) during three blocks of delayed pitch discrimination trials. The difference between target and probe tones was set to the individual's frequency detection threshold for 80% response-accuracy. Listeners with tinnitus also completed the Tinnitus Handicap Inventory (THI). Linear mixed effects procedures were applied to examine changes in baseline pupil diameter and TEPRs associated with group (tinnitus versus control), block (1 to 3) and their interaction. The association between THI scores and maximum TEPRs was assessed using simple linear regression. Patterns of baseline pupil dilation across trials diverged in listeners with tinnitus and controls. For controls, baseline pupil dilation remained constant across blocks. For listeners with tinnitus, baseline pupil dilation increased on blocks 2 and 3 compared with block 1. TEPR amplitudes were also larger in listeners with tinnitus than controls. Linear mixed effects models yielded a significant group by block interaction for baseline pupil diameter and a significant main effect of group on maximum TEPR amplitudes. Regression analyses yielded a significant association between THI scores and TEPR amplitude in listeners with tinnitus. Our data indicate measures of baseline pupil diameter, and TEPRs are sensitive to competition between tinnitus and external sounds during a test of auditory short-term memory. This result suggests pupillometry can provide an objective measure of intrusion in tinnitus. Future research will be required to establish whether our findings generalize to listeners across a full range of tinnitus severity.

Evaluation of the Electrically-Evoked Stapedial Reflex Threshold in Pediatric Cochlear Implant Users with High-Frequency Probe Tones.

Introduction Measurement of the electrically-evoked stapedial reflex threshold (ESRT) is an objective tool used to set the comfort levels in pediatric cochlear implant (PCI) users. The levels of ESRT have a strong correlation with comfort levels. However, the clinical utility of ESRT is limited because the ESRT response is not observed in all cochlear implant users. Objective To assess the effects of probe-tone frequency on ESRT and its relationship with the behavioral comfort levels in PCI users. Methods A total of 14 PCI users aged between 5 and 8 years participated in the study. The ESRT levels were measured using high-frequency probe tones (678 Hz and 1,000 Hz), and the default 226 Hz probe tone. The ESRT was measured with single-electrode stimulation across the three electrode locations (basal [E01]; middle [E11]; and apical [E22]). The ESRT levels measured with different probe tone frequencies were compared with the behavioral comfort levels. Results The mean ESRT levels using 1,000Hz and 678 Hz were lower than those measured using 226 Hz, but there was no main effect of probe-tone frequency ( p > 0.05). A significantly high incidence of successful ESRT measurements occurred with higher-frequency probe tone ( p < 0.039). Additionally, ESRT using higher probe tones significantly correlated with comfort levels. Conclusion The ESRT with higher probe tones was correlated with behavioral comfort levels and increased the success rate of the measurements. Higher-frequency probe tones may be useful whenever ESRT with 226 Hz is not measurable.

The Spectral Extent of Phasic Suppression of Loudness and Distortion-Product Otoacoustic Emissions by Infrasound and Low-Frequency Tones

We investigated the effect of a biasing tone close to 5, 15, or 30 Hz on the response to higher-frequency probe tones, behaviorally, and by measuring distortion-product otoacoustic emissions (DPOAEs). The amplitude of the biasing tone was adjusted for criterion suppression of cubic DPOAE elicited by probe tones presented between 0.7 and 8 kHz, or criterion loudness suppression of a train of tone-pip probes in the range 0.125–8 kHz. For DPOAEs, the biasing-tone level for criterion suppression increased with probe-tone frequency by 8–9 dB/octave, consistent with an apex-to-base gradient of biasing-tone-induced basilar membrane displacement, as we verified by computational simulation. In contrast, the biasing-tone level for criterion loudness suppression increased with probe frequency by only 1–3 dB/octave, reminiscent of previously published data on low-side suppression of auditory nerve responses to characteristic frequency tones. These slopes were independent of biasing-tone frequency, but the biasing-tone sensation level required for criterion suppression was ~ 10 dB lower for the two infrasound biasing tones than for the 30-Hz biasing tone. On average, biasing-tone sensation levels as low as 5 dB were sufficient to modulate the perception of higher frequency sounds. Our results are relevant for recent debates on perceptual effects of environmental noise with very low-frequency content and might offer insight into the mechanism underlying low-side suppression.

Relationship between irregularities in spontaneous otoacoustic emissions suppression and psychophysical tuning curves.

The suppression of spontaneous otoacoustic emissions (SOAEs) allows the objective evaluation of cochlear frequency selectivity by determining the suppression tuning curve (STC). Interestingly, some STCs have additional sidelobes at the high frequency flank, which are thought to result from interaction between the probe tone and the cochlear standing wave corresponding to the SOAE being suppressed. Sidelobes are often in regions of other neighboring SOAEs but can also occur in the absence of any other SOAE. The aim of this study was to compare STCs and psychoacoustic tuning curves (PTCs). Therefore, STCs and PTCs were measured in: (1) subjects in which the STC had a sidelobe, and (2) subjects without STC sidelobes. Additionally, PTCs were measured in subjects without SOAEs. Across participant groups, the quality factor Q10dB of the PTCs was similar, independently from whether SOAEs were present or absent. Thus, the presence of an SOAE does not provide enhanced frequency selectivity at the emission frequency. Moreover, both PTC and STC show irregularities, but these are not related in a straightforward way. This suggests that different mechanisms cause these irregularities.

The optimal probe tone frequency for eSRT measurements at individual electrodes in children with cochlear implants

Background Higher probe tone frequencies have been shown to increase the elicitation rates in electrically evoked stapedius reflex threshold (eSRT) measurements. Objectives To determine the optimal probe tone frequency for contralateral eSRT measurements at individual electrodes in children with unilateral cochlear implants and to assess the relationship between eSRTs for this frequency and most comfortable levels (M-levels). Materials and methods Contralateral eSRT measurements with three probe tone frequencies (226, 678, and 1000 Hz) at individual electrodes were performed on 26 paediatric Advanced Bionics cochlear implant recipients. Results The elicitation rates of eSRTs for 226, 678, and 1000 Hz probe tones were 73.08% (57/78), 88.46% (69/78), and 88.46% (69/78), respectively. The average eSRT for the 1000 Hz probe tone was significantly lower than those for 226 and 678 Hz probe tones (p<.001 and p=.009, respectively). ESRTs for the 1000 Hz probe tone and M-levels were significantly correlated at all tested electrodes (all p<.001). Conclusions and significance The optimal probe tone frequency for contralateral eSRT measurement at individual electrodes in children with unilateral cochlear implants is 1000 Hz. ESRTs for the 1000 Hz probe tone are significantly correlated with M-levels and can be used to guide the M-levels setting in these children.

Space oddity: musical syntax is mapped onto visual space

Increasing evidence has uncovered associations between the cognition of abstract schemas and spatial perception. Here we examine such associations for Western musical syntax, tonality. Spatial metaphors are ubiquitous when describing tonality: stable, closural tones are considered to be spatially central and, as gravitational foci, spatially lower. We investigated whether listeners, musicians and nonmusicians, indeed associate tonal relationships with visuospatial dimensions, including spatial height, centrality, laterality, and size, implicitly or explicitly, and whether such mappings are consistent with established metaphors. In the explicit paradigm, participants heard a tonality-establishing prime followed by a probe tone and coupled each probe with a subjectively appropriate location (Exp.1) or size (Exp.4). The implicit paradigm used a version of the Implicit Association Test to examine associations of tonal stability with vertical position (Exp.2), lateral position (Exp3) and size (Exp.5). Tonal stability was indeed associated with perceived physical space: the spatial distances between the locations associated with different scale-degrees significantly correlated with the tonal stability differences between these scale-degrees. However, inconsistently with musical discourse, stable tones were associated with leftward (instead of central) and higher (instead of lower) spatial positions. We speculate that these mappings are influenced by emotion, embodying the “good is up” metaphor, and by the spatial structure of music keyboards. Taken together, the results demonstrate a new type of cross-modal correspondence and a hitherto under-researched connotative function of musical structure. Importantly, the results suggest that the spatial mappings of an abstract domain may be independent of the spatial metaphors used to describe that domain.

Wideband tympanometry patterns in relation to intracranial pressure

Wideband tympanometry performs a more thorough analysis of middle-ear mechanics than the conventional single-frequency method with a 226-Hz probe tone. The present work examines the sensitivity of wideband tympanometry to the stiffness of the stapes-annular ligament system in relation to intracranial pressure (ICP) and labyrinthine fluid pressure. Here, body tilt allowed ICP to be set at different values. Sixty-eight ears of volunteers were tested sequentially in upright, supine, head-down (-30°) and upright postures. Energy absorbance of the ear was measured in these postures with a commercially available wideband-tympanometry device between 0.25 and 3 kHz, at ear-canal pressures between -600 and 300 daPa. In each posture, it was possible to find a single (posture-dependent) pressure in the ear canal at which a tympanometric peak occurred at all frequencies below about 1.1 kHz. The average across ears of tympanometric-peak pressure (TPP), close to 0 in upright posture, got increasingly positive, +19 daPa in supine and +27 daPa in head-down positions. The three-dimensional plot of energy absorbance against frequency and pressure displayed an invariant shape, merely shifting with TPP along the pressure axis. Thus, a properly adjusted ear-canal pressure neutralized the effects of ICP on the ear's energy absorbance. Comparisons to published invasive assessments of ICP in the different tested body positions led to the proposed relationship ICP ≈ 15 TPP, likely describing the transformer effect between tympanic membrane and stapes-annular ligament system at quasi-static pressures. With wideband tympanometry, the middle ear may serve as a precision scales for noninvasive ICP measurements.

Comparison of tympanometry results for probe tones of 226 Hz and 1000 Hz in newborns

IntroductionImpedance audiometry is a routine test for diagnosing hearing disorders in children. Typically, tympanometry uses a 220 or 226 Hz probe tone. However, using a 1000 Hz test tone is becoming increasingly popular, particularly in newborns, since it enables one to assess individual components of the ear's admittance. AimThis study compares tympanograms for test frequencies of 226 Hz and 1000 Hz in newborns and evaluate the rate of occurrence of each type of tympanogram for both frequencies. Material and methodThe study material was 53 newborns. All newborns underwent middle ear susceptibility testing at two measurement frequencies: 226 Hz and 1000 Hz. The parameters obtained with both frequencies were compared, and the utility of the 1000 Hz test frequency for middle ear diagnostics in newborns was evaluated. ResultsThe results show that tympanograms obtained from the same ear using different test frequencies are significantly different. The 1000 Hz tone produced a higher rate of type B tympanograms (flat). ConclusionsTympanometry curves for 226 Hz and 1000 Hz are different, and in newborns the 1000 Hz test tone revealed a higher rate of middle ear pathology. However, further studies are required to verify that 1000 Hz tympanometry is a high-sensitivity diagnostic method for middle ear problems in newborns.

Acoustic immittance measures and middle ear assessment: Current practice by South African audiologists.

BackgroundLimited research exists regarding South African audiologists’ practice with acoustic immittance. This study was part of a bigger study titled ‘Wideband acoustic immittance in adults living with human immunodeficiency virus’.ObjectivesThe purpose of the study was to explore current practice of South African audiologists regarding acoustic immittance measures, and to explore their perceived knowledge and views on acoustic immittance advancements.MethodA quantitative survey with a cross sectional design was employed. An electronic questionnaire was distributed to participants via professional associations of audiologists. Data was analysed through descriptive and inferential statistics.ResultsMost audiologists worked in private practice and conducted tympanometry with 226Hz probe tone and ipsilateral acoustic reflexes. There was no association between clinical setting, levels of qualification, and the use of tympanometry. None of the participants included multifrequency and multicomponent tympanometry (MFT) and/or wideband acoustic immittance (WAI) in their test battery. Most of the participants were not familiar with MFT and WAI. Familiarity with MFT and WAI were only associated with the level of qualification. Limited training and lack of equipment were major barriers to conducting some of the acoustic immittance measures. Most participants believed that they would include MFT and/or WAI in their test battery if they had access to the equipment.ConclusionCurrent findings raise training and clinical implications for the South African audiologists, including training institutions. These findings provide motivation for strategic resource allocation, planning and distribution of audiology clinics in the country if positive preventive audiology outcomes are to be achieved.