A comparison of inter-aural attenuation with the Etymotic ER-3A insert earphone and the Telephonics TDH-39 supra-aural earphone.

One of the many reported advantages of the insert earphone over the supra-aural earphone is increased inter-aural attenuation (IA). Minimum values of IA determine the need for masking of the non-test ear in air-conduction audiometry. The aim of the present study was to measure inter-aural attenuation for the Etymotic Research ER-3A insert earphone (with deep and shallow insertion of the ear plug within the ear canal) and compare this with the supra-aural Telephonics TDH-39/MX41-AR earphone/cushion combination. Subjects were 18 adults ranging in age from 38 to 68 years (mean 50 years). Each subject had no hearing in one ear following translabyrinthine surgery for removal of an acoustic neuroma. The opposite ear had hearing thresholds better than 40 dB HL and an air-bone gap of less than 10 dB at any audiometric frequency. Pure tone air-conduction thresholds were obtained in the range 0.25-8 kHz. Deep insertion of the insert earphone was deemed to occur when the outside edge of the ear plug was flush with the entrance of the ear canal. Shallow insertion was deemed to occur when half of the ear plug (6 mm) was inside the entrance of the ear canal. IA was defined operationally as the difference between the good-ear and poor-ear not-masked air conduction threshold for a given audiometric frequency and earphone. The results show that the TDH-39/MX41-AR combination provides a median IA of approximately 60 dB with a lower limit of approximately 45 dB. Greater IA was obtained with the ER-3A insert earphone but this depended on the depth of insertion. With a deep insertion, the 1A values were some 15-20 dB greater than with the supra-aural earphone. Although frequency-specific IA values are provided, a simple rule of thumb is to apply masking to the non-test ear when the pure tone airconduction signal from the ER-3A insert earphone exceeds the bone conduction threshold of the non-test ear by 55 dB HL or more. If it is not possible to obtain a deep insertion depth this value should be reduced by 5 dB.     

High-frequency audiometry. Masking of air- and bone-conduction signals.

Interaural attenuation has been investigated for both air-conduction and bone-conduction signals in the frequency ranges 0.25-18 and 0.25-16 kHz respectively. Ear canal occlusion is recommended when using the Koss HV/1A earphone for BC masking, as acoustic transmission occurs through the headset in the high-frequency range. Minimum masking levels for 1/3-octave filtered white noise were established for bone-conduction signals in the frequency range 8-16 kHz. Central masking of bone-conduction signals proved to be of the same order of magnitude in the conventional- and high-frequency ranges, while the cross-masking level was approximately 10-15 dB lower above 6 kHz. Recommendations are made for a masking procedure in the high frequency range.     

How does the sound pressure generated by circumaural, supra-aural, and insert earphones differ for adult and infant ears?

OBJECTIVE: To determine how the ear canal sound pressure levels generated by circumaural, supra-aural, and insert earphones differ when coupled to the normal adult and infant ear. DESIGN: The ratio between the sound pressure generated in an adult ear and an infant ear was calculated for three types of earphones: a circumaural earphone (Natus Medical, ALGO with Flexicoupler), a supra-aural earphone (Telephonics, TDH-49 with MXAR cushion), and an insert earphone placed in the ear canal (Etymoup and down arrow tic Research, ER-3A). The calculations are based on (1) previously published measurements of ear canal impedances in adult and infant (ages 1, 3, 6, 12, and 24 months) ears (Keefe et al., 1993, Acoustic Society of America, 94:2617-2638), (2) measurements of the Thévenin equivalent for each earphone configuration, and (3) acoustic models of the ear canal and external ear. RESULTS: Sound-pressure levels depend on the ear canal location at which they are measured. For pressures at the earphone: (1) Circumaural and supra-aural earphones produce changes between infant and adult ears that are less than 3 dB at all frequencies, and (2) insert earphones produce infant pressures that are up to 15 dB greater than adult pressures. For pressures at the tympanic membrane: (1) Circumaural and supra-aural earphones produce infant pressures that are within 2 dB of adult ears at frequencies below 2000 Hz and that are 5 to 7 dB smaller in infant ears than adult ears above 2000 Hz, and (2) insert earphones produce pressures that are 5 to 8 dB larger in infant ears than adult ears across all audiometric frequencies. CONCLUSIONS: Sound pressures generated by all earphone types (circumaural, supra-aural, and insert) depend on the dimensions of the ear canal and on the impedance of the ear at the tympanic membrane (e.g., infant versus adult). Specific conclusions depend on the location along the ear canal at which the changes between adult and infant ears are referenced (i.e., the earphone output location or the tympanic membrane). With circumaural and supra-aural earphones, the relatively large volume of air within the cuff of the earphone dominates the acoustic load that these earphones must drive, and differences in sound pressure generated in infant and adult ears are generally smaller than those with the insert earphone in which the changes in ear canal dimensions and impedance at the tympanic membrane have a bigger effect on the load the earphone must drive.     

A comparison of the variability in thresholds measured with insert and conventional supra-aural earphones

The purpose of this study was to evaluate the reliability and comparability of the commercially available insert earphone Etymotic Research ER-3A and the commonly available supra-aural TDH earphone. Thirteen subjects were tested five times with the ER-3A and five times with TDH-49P with MX-41/AR cushions. Threshold determinations were obtained utilizing a sweep-frequency audiometer in the range 0.25-8 kHz. The results showed that the reliability of the ER-3A earphone as measured by intra-individual variation, was comparable to that obtained with the TDH earphone. No evidence was found indicating an increased variability due to the positioning of the insert earphone's coupling device in the ear canal. Comparison of thresholds obtained with both devices indicated that the manufacturer's suggested correction values were appropriate.     

Attenuation provided by four different audiometric earphone systems

The attenuation provided by TDH earphones in MX-41/AR and P/N 51 cushions, Audiocup earphone enclosures and ER-3A insert earphones with ER3-14 foam earplugs was determined for 30 normally hearing subjects using a real-ear attenuation at threshold paradigm. The MX-41/AR and P/N 51 cushions provided about the same amount of attenuation which was less than the attenuation provided by the Audiocup enclosures. The ER-3A/ER3-14 provided the highest amount of attenuation. The MX-41/AR and ER-3A/ER3-14 attenuation values were in agreement with other studies using similar methodology. However, the attenuation provided by the Audiocup enclosures was considerably less, in the lower frequencies, than reported in two other studies. ANSI S3.1-1977 supra-aural earphone cushion attenuation values, which were determined using pure-tones presented in a free-field, should be replaced by earphone cushion attenuation values determined with 1/3 octave bands of noise presented in a diffuse sound field.     

Three studies comparing performance of the ER-3A tubephone with the TDH-50P earphone

Three studies compared the performance of the ER-3A Tubephone insert earphone and the TDH-50P-MX41/AR supra-aural earphone. The three factors addressed were: threshold differences in children 7 to 10 yr old compared to adults, differences in real ear attenuation, and threshold differences in the presence of high background noise levels. The influence of insertion depth of the ER-3A Tubephone was also investigated. Findings showed no significant threshold differences between children and adults, significantly better real ear attenuation for the ER-3A Tubephone, and significantly better thresholds for the ER-3A in the presence of high background noise levels. Most critically, there was a significant change in attenuation characteristics of the ER-3A Tubephone, which was dependent on the insertion depth of the ear-tip.     

Use of the 'real-ear to dial difference' to derive real-ear SPL from hearing level obtained with insert earphones

The electroacoustic characteristics of a hearing instrument are normally selected for individuals using data obtained during audiological assessment. The precise inter-relationship between the electroacoustic and audiometric variables is most readily appreciated when they have been measured at the same reference point, such as the tympanic membrane. However, it is not always possible to obtain the real-ear sound pressure level (SPL) directly if this is below the noise floor of the probe-tube microphone system or if the subject is unco-operative. The real-ear SPL may be derived by adding the subject's real-ear to dial difference (REDD) acoustic transform to the audiometer dial setting. The aim of the present study was to confirm the validity of the Audioscan RM500 to measure the REDD with the ER-3A insert earphone. A probe-tube microphone was used to measure the real-ear SPL and REDD from the right ears of 16 adult subjects ranging in age from 22 to 41 years (mean age 27 years). Measurements were made from 0.25 kHz to 6 kHz at a dial setting of 70 dB with an ER-3A insert earphone and two earmould configurations: the EAR-LINK foam ear-tip and the subjects' customized skeleton earmoulds. Mean REDD varied as a function of frequency but was typically approximately 12 dB with a standard deviation (SD) of +/- 1.7 dB and +/- 2.7 dB for the foam ear-tip and customized earmould, respectively. The mean test-retest difference of the REDD varied with frequency but was typically 0.5 dB (SD 1 dB). Over the frequency range 0.5-4 kHz, the derived values were found to be within 5 dB of the measured values in 95% of subjects when using the EAR-LINK foam ear-tip and within 4 dB when using the skeleton earmould. The individually measured REDD transform can be used in clinical practice to derive a valid estimate of real-ear SPL when it has not been possible to measure this directly.     

High-frequency audiometry using precision earphones: reliability under laboratory and field conditions

New circumaural earphones were tested in the frequency range from 100 Hz to 20 kHz and compared to commonly used supra-aural earphones. The circumaural earphone HD 230 (Sennheiser) generates test stimuli at up to 20 kHz with almost constant sound pressure levels when its pos ed on an artificial ear. The reproducibility of hearing threshold mea ed with a new microprocessor-controlled Békésy audiometer using the ne was nearly as good as under free-field conditions. The practicabil diagnostic value of high-frequency audiometry have been demonstrated er field conditions. For this application, the good sound attenuation these earphones (30 dB above 1 kHz) are important. High-frequency he ds of healthy pupils and of pupils with a history of otitis media are kHz, the hearing threshold level difference between both groups reached 20 dB.     

TIP-300插入式耳机与TDH-50P耳罩式耳机的耳间衰减比较

目的 比较TIP-300插入式耳机耳间衰减(insert earphone interaural attenuation,IEIA)与TDH-50P耳罩式耳机耳间衰减(supra-aural earphone interaural attenuation,SELA)的差异，为TIP-300插入式耳机的临床应用提供参考依据。方法 利用GSI61临床听力计、TIP-300插入式耳机和TDH-50P耳罩式耳机，对一组单耳全聋而另一耳听力正常者35人(男13人，女22人)进行纯音气导的耳间衰减测试。结果 TIP-300插入式耳机与TDH-50P耳罩式耳机组间耳间衰减有显著性差异；其中TIP-300插入式耳机组内的某些频率之间耳间衰减也有显著性差异。结论 在低中频测听范围，TIP-300插入式耳机的耳间衰减比TDH-50P耳罩式耳机大。     

A New Masking Transducer with Low Contralateral Transmission

A new making transducer is presented which uses a large moving coil driving unit acoustically shielded in a plastic shell. Sound waves are conveyed to the ear by means of a flexible plastic tube and an insert nipple. In tests made under normal clinical situations, it has been found ot provide an interaural isolation from 20-50 dB better than the conventional supra-aural audio-metric earphone and 16-34 dB better than the common hearing-aid type of insert erphone, while being more rugged and more reliable than the latter. It is therefore proposed as a supplementary tool to the clinician, for masking in all cases where other types of transducers are inadequate     

The influence of RECD transducer when deriving real-ear sound pressure level

OBJECTIVE: The main aim of the present study was to compare the derived and directly measured real-ear hearing instrument performance for a range of commonly used hearing instruments. A secondary aim was to compare the real-ear to coupler difference (RECD) measured using the ER-3A insert earphone and a selection of hearing instruments. DESIGN: The real-ear SPL was measured for four models of hearing instrument in 20 adult participants using an Audioscan RM500 real-ear system. This was compared with the derived real-ear SPL obtained by adding the RECD (measured using the ER-3A insert earphone) to the 2-cc coupler response of each hearing instrument. Measurements were made at 1/12 octave intervals from 0.2 to 6 kHz, using both the HA1 and HA2 2-cc coupler. In addition, the RECD was measured using four models of hearing instrument for comparison with the ER-3A insert earphone values. RESULTS: The procedures were very reliable with mean differences on retest of less than 1 dB. Repeated-measures analysis of variance revealed statistically significant differences between the measured and derived real-ear SPL (p < 0.001) for several models of hearing instrument. The derived responses using the HA1 coupler yielded good accuracy, whereas the HA2 yielded less accuracy. For three models of hearing instrument, the maximum difference was between 5 and 10 dB when using the HA2 coupler. The mean RECD measured with the ER-3A insert earphone and HA2 coupler was not always equivalent to the RECD measured with the hearing instruments. CONCLUSIONS: The accuracy of the derived real-ear response obtained using an RECD, measured with an ER-3A insert earphone, is very good when an HA1 is used for the coupler component of the RECD. The accuracy diminishes somewhat with the HA2 coupler, especially for undamped hearing instruments. The accuracy of the derived real-ear response is very good when the RECD is measured using the hearing instrument and the HA1 or the HA2 coupler.     

Middle ear pathology can affect the ear-canal sound pressure generated by audiologic earphones

OBJECTIVE: To determine how the ear-canal sound pressures generated by earphones differ between normal and pathologic middle ears. DESIGN: Measurements of ear-canal sound pressures generated by the Etymtic Research ER-3A insert earphone in normal ears (N = 12) were compared with the pressures generated in abnormal ears with mastoidectomy bowls (N = 15), tympanostomy tubes (N = 5), and tympanic-membrane perforations (N = 5). Similar measurements were made with the Telephonics TDH-49 supra-aural earphone in normal ears (N = 10) and abnormal ears with mastoidectomy bowls (N = 10), tympanostomy tubes (N = 4), and tympanic-membrane perforations (N = 5). RESULTS: With the insert earphone, the sound pressures generated in the mastoid-bowl ears were all smaller than the pressures generated in normal ears; from 250 to 1000 Hz the difference in pressure level was nearly frequency independent and ranged from -3 to -15 dB; from 1000 to 4000 Hz the reduction in level increased with frequency and ranged from -5 dB to -35 dB. In the ears with tympanostomy tubes and perforations the sound pressures were always smaller than in normal ears at frequencies below 1000 Hz; the largest differences occurred below 500 Hz and ranged from -5 to -25 dB. With the supra-aural earphone, the sound pressures in ears with the three pathologic conditions were more variable than those with the insert earphone. Generally, sound pressures in the ears with mastoid bowls were lower than those in normal ears for frequencies below about 500 Hz; above about 500 Hz the pressures showed sharp minima and maxima that were not seen in the normal ears. The ears with tympanostomy tubes and tympanic-membrane perforations also showed reduced ear-canal pressures at the lower frequencies, but at higher frequencies these ear-canal pressures were generally similar to the pressures measured in the normal ears. CONCLUSIONS: When the middle ear is not normal, ear-canal sound pressures can differ by up to 35 dB from the normal-ear value. Because the pressure level generally is decreased in the pathologic conditions that were studied, the measured hearing loss would exaggerate substantially the actual loss in ear sensitivity. The variations depend on the earphone, the middle ear pathology, and frequency. Uncontrolled variations in ear-canal pressure, whether caused by a poor earphone-to-ear connection or by abnormal middle ear impedance, could be corrected with audiometers that measure sound pressures during hearing tests.     

Attenuation values for a supra-aural earphone for children and insert earphone for children and adults.

Earphone attenuation values were determined for 17 children (6-14 years old) using supra-aural (TDH-49P/Model 51 cushion) and insert earphones (E-A-Rtone 3A) terminated by an E-A-Rlink 3A (for normal size ear canals) or E-A-Rlink 3B (for small size ear canals) foam eartips, and for 10 adults having small ear canals using insert earphones and E-A-Rlink 3B foam eartips. The test signals were 1/3-octave bands of noise presented in a diffuse sound field (re: ANSI S12.6-1984). The supra-aural earphone attenuation values for the children were slightly higher (more attenuation) or similar to reported adult values, and always lower (less attenuation) compared with insert earphone/E-A-Rlink 3A (IE/3A) or 3B (IE/3B) values for both children and adults. The IE/3B attenuation values were similar between the children and adults and provided slightly more attenuation than the IE/3A. Overall, the results indicated that the ANSI S3.1-1991 maximum permissible ambient noise levels allowed in a test room for ears covered testing with a supra-aural earphone, which were determined using adult values, are appropriate for testing children. Future revisions of ANSI S3.1-1991 may include maximum permissible ambient noise levels for testing with insert earphones. The IE/3A and IE/3B attenuation values could be used for that purpose. In the meantime, because more attenuation was provided by the IE/3A and IE/3B, they can be used for testing both children and adults in higher ambient noise levels than specified in ANSI S3.1-1991.     

Test-retest variability in audiometric threshold with supraaural and insert earphones among children and adults

The effect of age and earphone condition on test-retest intrasubject variability in audiometric threshold was investigated. Ten subjects in each of the following age groups were investigated: 6-9 years, 10-13 years and young adults. Test-retest audiometric thresholds were collected at six frequencies (250, 500, 1,000, 2,000, 4,000 and 8,000 Hz) under three earphone conditions (Telephonics TDH-50P supraaural and Etymotic Research ER-3A insert earphone coupled to an immittance probe cuff or a foam insert). No statistically significant differences were found in variability of test-retest differences as a function of age, earphone condition or test frequency (p greater than 0.05). The clinical application of the insert earphone is recommended with children and adults as it affords no greater test-retest variability and at the same time provides a solution to a number of limitations incurred with the use of the supraaural earphone.     

Variation of young normal-hearing thresholds measured using different audiometric earphones: implications for the acoustic coupler and the ear simulator

This paper questions the necessity for two calibration devices to measure the acoustic output from different types of audiometric earphones. International standards give the audiometric zero for TDH39 earphones on the IEC 60318-3 acoustic coupler; the IEC 60318-1 ear simulator is intended for other supra-aural earphone types. If hearing threshold samples from young, healthy ears were found to be more variable using TDH39 earphones, then that earphone and its coupler might be taken out of service. The audiological literature yielded threshold survey results for over 5100 otologically normal ears of subjects aged 31 years or less. These independent samples showed smaller variation for TDH39 samples than for samples using other earphones; this finding does not support abandoning the TDH39 and its coupler. Nevertheless, benefits accrue from calibrating TDH39 output to the audiometric zero as measured on the ear simulator.     

Variation of young normal-hearing thresholds measured using different audiometric earphones: Implications for the acoustic coupler and the ear simulator

This paper questions the necessity for two calibration devices to measure the acoustic output from different types of audiometric earphones. International standards give the audiometric zero for TDH39 earphones on the IEC?60318-3 acoustic coupler; the IEC?60318-1 ear simulator is intended for other supra-aural earphone types. If hearing threshold samples from young, healthy ears were found to be more variable using TDH39 earphones, then that earphone and its coupler might be taken out of service. The audiological literature yielded threshold survey results for over 5100 otologically normal ears of subjects aged 31 years or less. These independent samples showed smaller variation for TDH39 samples than for samples using other earphones; this finding does not support abandoning the TDH39 and its coupler. Nevertheless, benefits accrue from calibrating TDH39 output to the audiometric zero as measured on the ear simulator.     

Is the real-ear to coupler difference independent of the measurement earphone?

Direct measurement of real-ear hearing aid performance can be obtained using a probe tube microphone system. Alternatively, it can be derived by adding the real-ear to coupler difference (RECD) to the electroacoustic performance of the hearing instrument measured in a 2-cc coupler. Inherent in this derivation is the assumption that the RECD measured with one transducer can be applied to a coupler measurement performed with a different transducer. For the RECD procedure to be valid, it should be independent of the measurement transducer. The Audioscan RM500 is an example of a commercially available real-ear measurement system that incorporates a clinical protocol for the measurement of the RECD. The RECD can be measured on the Audioscan RM500 using a standard EAR-Tone ER-3A insert earphone or the Audioscan's own RE770 insert earphone. The aim of this study was to compare the RECDs obtained with these two earphones. The Audioscan RM500 was used to measure the RECD from the right ears of 18 adult subjects ranging in age from 22 to 36 years (mean 25 years). Measurements were made with the EAR-Tone ER-3A and RE770 insert earphone and three earmould configurations: (1) the EARLINK foam ear-tip; (2) a hard acrylic shell earmould with the same length of acoustical tubing as the foam ear-tip (25 mm); and (3) the shell ear mould with the appropriate length of tubing for a behind-the-ear (BTE) hearing aid fitting (approximately 35-45 mm). The results show that the mean RECD was around 3 dB higher at 1.5 kHz with the foam ear-tip when measured with the RE770 earphone than when measured with the ER-3A earphone. The same magnitude of difference was obtained with the shell earmould and 25-mm tubing; however, this increased to 9 dB when the tubing was increased to around 40 mm for a BTE fitting. The difference in mean RECD with the two earphones was statistically significant on a repeated-measures ANOVA for every earmould configuration (p<0.001). The results of this study demonstrate that the RECD procedure that uses an HA2 coupler and earmould is not independent of the measurement earphone. This has important implications for clinical practice.     

Reference equivalent threshold sound pressure levels for insert earphones

Insert earphones, coupled to the ear canal by means of a long plastic tube and soft ear plug (Etymotic Research ER-3A Tubephone) are being used for a number of audiometric applications as an alternative to supra-aural earphones. This report presents the results of hearing threshold level measurements in 36 ears of young, otologically normal listeners. The results are expressed as mean sound pressure levels measured on a 2 cm3 coupler according to IEC 126 as well as on an ear simulator according to IEC 711.     

Earphones in extended high-frequency audiometry and ISO 389-5

Abstract

Objective: To determine common reference equivalent threshold sound pressure levels (RETSPL) for the earphones used in the extended high-frequency (EHF) range, as different earphones are commercially available, but there are not RETSPLs for each model. Design: Hearing threshold sound pressure levels were measured up to 20 kHz for the Sennheiser HDA 200 audiometric earphone, and were compared to the ISO 389-5 (2006) norm and other investigations using that earphone and different ones. Study sample: A total of 223 otologically-normal subjects (aged 5–25 years old) participated in the hearing determination. Results: The results are in good agreement with previous studies of hearing thresholds using the same and other earphones. Conclusions: The results of the present investigation are relevant for the international standard for the calibration of audiometric equipment in the 8 to 16 kHz frequency range, ISO 389-5. The data may be used for a future update of the RETSPL for circumaural and insert audiometric earphones.     

Equivalent hearing threshold levels for the Etymotic Research ER-10C otoacoustic emission probe

Objective: To determine the equivalent threshold sound pressure levels (ETSPL) for a commercially available distortion product otoacoustic emission (DPOAE) probe, and to study the impact of probe fitting and eartip size on the calibration. Design: Twenty-eight otologically normal test subjects participated in the ETSPL determination for the Etymotic Research ER-10C probe. Study sample: ETSPLs were determined up to 16 kHz and were compared to the reference hearing thresholds associated with the ER-3A insert earphone. Both ‘regular’ and ‘baby’ foam eartips were used. Results: At most frequencies, no significant threshold differences were observed between the insert earphone and the DPOAE probe. However, at 1 kHz and 4 kHz, the mean thresholds for the insert earphone were generally lower than those for the DPOAE probe, suggesting systematic differences at those frequencies. Repeated calibration runs resulted in deviations of about 0.6 dB. Similar deviations were noticed when using foam eartips of different sizes up to 10 kHz. Conclusions: Knowing the reference thresholds for DPOAE probes enables measurements of (subjective) hearing thresholds and (objective) otoacoustic emissions using the same probe. Probe fitting and eartip size had negligible effect on the determination of ETSPLs. The obtained data may be proposed for inclusion in future audiometry standards.