An audiovisual test of hearing disability using free-field sentences in noise

An audiovisual test, using BKB sentences in noise, has been developed to assess hearing disability, unaided and aided with a hearing aid(s), in severely hearing-impaired individuals. After a single practice list, no significant further increases in performance were detected. The test is reproducible within and between test sessions.     

Dynamic free-field headphone as hearing aid transducer. A preliminary report

A comparison between a body-worn hearing aid with a conventional earphone/earmould system, and a free-field dynamic headphone demonstrated the significance of the coupling between the hearing aid earphone and the subject's ear. Measurement of the insertion gain revealed destruction of the ear-canal resonance with a conventional earmould, whereas the ear-canal resonance was preserved by the use of a dynamic headphone. The use of a body-worn hearing aid connected to a dynamic headphone showed a greater amplification at low as well as at high frequencies. Furthermore, a significantly better discrimination score and an improved sound quality were demonstrated with the dynamic headphone.     

Reference hearing threshold levels for short duration signals

Hearing thresholds for clicks and tonebursts were measured on 26 otologically normal persons (age 18–25 years) using the earphones Sennheiser HDA 200 and Telephonics TDH 39. The test signals are specified in IEC 60645-3 and in ISO 389-9. The acoustic test signals were presented both as a single stimulus and as repeated stimuli with the repetition rate of 20 Hz. The frequencies used for the toneburst were: 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. Test signals and measurement methods were all in accordance with the recommendations given in ISO 389-9: Preferred test conditions for the determination of reference hearing threshold levels. The results are given as peak-to-peak equivalent threshold sound pressure levels (peETSPL). The results are in good agreement with other sparse results from literature and are part of the basis for the ISO 389-6 standard from 2007.     

Reference hearing threshold levels for short duration signals

Hearing thresholds for clicks and tonebursts were measured on 26 otologically normal persons (age 18-25 years) using the earphones Sennheiser HDA 200 and Telephonics TDH 39. The test signals are specified in IEC 60645-3 and in ISO 389-9. The acoustic test signals were presented both as a single stimulus and as repeated stimuli with the repetition rate of 20 Hz. The frequencies used for the toneburst were: 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. Test signals and measurement methods were all in accordance with the recommendations given in ISO 389-9: Preferred test conditions for the determination of reference hearing threshold levels. The results are given as peak-to-peak equivalent threshold sound pressure levels (peETSPL). The results are in good agreement with other sparse results from literature and are part of the basis for the ISO 389-6 standard from 2007.     

Predicting hearing aid microphone preference in everyday listening

Seventeen hearing-impaired adults were fit with omnidirectional/directional hearing aids, which they wore during a four-week trial. For each listening situation encountered in daily living during a total of seven days, participants selected the preferred microphone mode and described the listening situation in terms of five environmental variables, using a paper and pencil form. Results indicated that hearing-impaired adults typically spend the majority of their active listening time in situations with background noise present and surrounding the listener, and the signal source located in front and relatively near. Microphone preferences were fairly evenly distributed across listening situations but differed depending on the characteristics of the listening environment. The omnidirectional mode tended to be preferred in relatively quiet listening situations or, in the presence of background noise, when the signal source was relatively far away. The directional mode tended to be preferred when background noise was present and the signal source was located in front of and relatively near the listener. Results suggest that knowing only signal location and distance and whether background noise is present or absent, omnidirectional/directional hearing aids can be set in the preferred mode in most everyday listening situations. These findings have relevance for counseling patients when to set manually switchable omnidirectional/directional hearing aids in each microphone mode, as well as for the development of automatic algorithms for selecting omnidirectional versus directional microphone processing.     

Effects of simulated conductive hearing loss on dichotic listening performance for digits

This experiment assessed conditions under which simulated conductive hearing loss would affect performance on a digit dichotic test. Losses were simulated by insertion of EAR plugs, and each subject served as his/her own control. Performance for left ear plugged and right ear plugged conditions was compared with performance in a normal hearing condition (neither ear plugged). Conductive losses did not affect dichotic performance at test intensities 12 dB above the "knees" of monotic performance-intensity functions for the plugged ears (95% correct points) but did affect dichotic performance for some listeners at intensities that were within 8 dB of the monotic knees.     

Clinical trials with a programmable hearing aid set for various listening environments

A conventional hearing aid has a frequency response that does not change much at normal listening levels. It is therefore unlikely that optimal speech intelligibility and optimal listening comfort can be obtained simultaneously, or in different listening environments. With a programmable hearing aid with multiple memories the listener can choose between a range of sound pictures, which increases the chance of finding a suitable frequency curve for each listening situation. The programmable hearing aid with eight separate settings stored in eight memories, was compared with personal hearing aids fitted according to the recommendations of the National Acoustic Laboratories (NAL) by 22 experienced hearing aid users. One memory of the programmable hearing aid was initially fitted according to the NAL recommendation. The other memories were programmed to give variations around that recommendation. One aim was to investigate whether the hearing-impaired user took advantage of different frequency responses to achieve listening improvements in acoustically different environments. Another aim was to evaluate the ergonomic and acoustical features of the programmable hearing aid, compared with other well fitted hearing aids. The evaluations were based on comparisons of the test hearing aid to the personal aid for each subject, looking at speech tests, direct paired comparison judgements, sound quality judgements and interviews. A majority of the subjects experienced substantial benefit from being able to use different frequency response curves in different environments. With the test hearing aid the subjects performed better in speech discrimination tests in noise.(ABSTRACT TRUNCATED AT 250 WORDS)     

New hearing test for functional deafness--the procedure to estimate the genuine hearing threshold]

This report describes a new procedure for examining functional deafness with binaural sound stimulation. This new hearing test can estimate the genuine pure tone hearing threshold quantitatively at every frequency by using the ordinary audiometer. In the case of the nonorganic deafness, even if the hearing disorders are bilateral or hemilateral, we believe that measuring auditory threshold separately, causes the deterioration of the threshold. Therefore, this procedure is designed so that the subject may not be aware of testing the auditory acuity of each ear, and utilizes the response of the phantom sound image in the head by simultaneous binaural presentation of sound stimulation. Our strategy is based on the following facts. If the normal subject has the same pure tone threshold level in both ears, the phantom sound image is formed in the median plane of the head by the equal suprathreshold tone level presented simultaneously in each ear. In the case of a unilateral auditory disorder, the sound image is localized to the center of the head only when sound stimulation louder than the threshold level of affected ear is given to both ears at the same time. Simultaneous binaural sound stimulation at a lower level than the threshold of the affected ear forms a lateralized sound image to the unaffected ear in the head. For patients with bilaterally similar hearing loss, the sound image is not formed if the stimulation is less than the threshold level of the pure tone. The band noise in the phase of each frequency with 50 dB HL was given binaurally to 10 normal hearing subjects, and the localization of the sound image formation was examined. This experiment confirmed that around the occipital region of the median plane in all subjects. Furthermore, comparing the formation threshold of the median plane image with the pure tone auditory threshold, proved that there was no significant difference statistically in either value. As a next step, 15 patients with unilateral sensorineural deafness were examined with this technique and we knew that the median sound images would not be formed with stimulation less than the pure tone auditory threshold of the affected ear. For clinical application, patients were classified into two groups with unilateral (6) and bilateral (2) functional deafness, and examined. Midline sound images definitely were formed with the lower magnitude of sound than the pure tone threshold by hemilateral nonorganic deafness. The difference of the forming threshold of the median sound image and the average of pure tone hearing level of the affected ear were maximum 100 dB, minimum 35 dB, and mean 69.4 dB. Furthermore, the difference of the median image forming threshold and the average hearing level of the unaffected ear were maximum 35 dB, minimum 0 dB, and mean 15.4 dB. In bilateral disorders, the midline plane sound image was formed with the corresponding level of the pure tone value in one subject, though the other one was determined by the maneuver method because it did not form a midline sound image. In conclusion, this examination can be readily used to estimate the genuine hearing threshold of the functional deafness.     

Headphone listening habits,hearing thresholds and listening levels in Swedish adolescents with severe to profound HL and adolescents with normal hearing

Abstract

Objective: Research has minimally focussed on the music listening habits and preferred sound volumes among adolescents with severe to profound congenital HL. Listening to music played at loud sound volumes and for a long duration of time could imply risks of worsening the HL. Therefore, it is important to investigate the listening habits in adolescents with HL. The aim of the present study was to describe the use of personal music devices, subjective estimated sound levels, measured sound levels, listening habits, and hearing symptoms in adolescents with severe to profound hearing loss compared with adolescents with normal hearing.

Design: The study was conducted in two steps. First, a questionnaire was given to students with or without hearing loss. In step two, hearing and sound level measurements were made in a subsample from both groups.

Study sample: The study sample were based on 112 seventeen-year-old students with severe to profound hearing loss and 279 adolescents with normal hearing. Hearing thresholds and listening levels was measured on two subsamples based on 29 adolescents with severe to profound hearing loss and 50 adolescents from the group with normal hearing.

Results: The results showed that adolescents with severe to profound hearing loss listened to significantly louder sound levels for longer periods. For both groups, those listening at louder sound levels had poorer hearing thresholds. This finding is especially alarming for subjects with hearing loss. Among those listening above 85?dB per occasion, the sound level ranged between 85.8?dB up to 109?dB for those with hearing loss, whereas the sound level ranged between 85.5?dB and 100?dB for those with normal hearing.

Conclusions: Adolescents with congenital hearing loss used portable music devices in the same manner as adolescents with normal hearing. However, adolescents with hearing loss listened to louder sound volumes most likely to compensate for their hearing loss, which significantly increases the risk of further damage to their hearing. From a hearing rehabilitation perspective it could be concluded that aspect of music listening habits should be focussed in order to prevent noise induced hearing loss among individuals with congenital hearing loss.     

Changes of hearing threshold in the elderly

A 10-year and 5-year longitudinal study of the hearing threshold of the aged was performed during 1977-1987 and 1982-1987. The results showed that the annual hearing loss was 1.0dB in the 10-year group, 1.03dB in the 5-year group for males and 0.7dB in the 5-year group for females. Annual hearing loss in the aged with hypertension, hyperlipidemia, cerebral arteriosclerosis and diabetes was much higher than that in the healthy ones (P less than 0.05). The rates of hearing loss between 60 and 70 years of age was not significantly different among the healthy males (P greater than 0.05). In the 5-year group the hearing loss at 4-8k Hz was much milder in the healthy females than in the healthy male s (P less than 0.05).     

Wireless binaural hearing aid technology for telephone use and listening in wind noise

Objective: To assess the speech perception benefits of binaural streaming technology for bilateral hearing aid users in two difficult listening conditions.

Design: Two studies were conducted to compare hearing aid processing features relating to telephone use and wind noise. Speech perception testing was conducted in four different experimental conditions in each study.

Study sample: Ten bilaterally-aided children in each study.

Results: Significant improvements in speech perception were obtained with a wireless feature for telephone use. Significant speech perception benefits were also obtained with wireless hearing aid features when listening to speech in simulated wind noise.

Conclusions: Binaural signal processing algorithms can significantly improve speech perception for bilateral hearing aid users in challenging listening situations.     

Signal-to-noise threshold with and without hearing aid

We determined the necessary signal-to-noise threshold for 50% sentence discrimination in 130 patients with sensorineural hearing disorders with and without a hearing aid, as well as the minimum monosyllable discrimination loss without hearing aid. A significant correlation coefficient was found to exist of the signal-to-noise threshold with vs. that without hearing aid (r = 0.61), and between the minimum discrimination loss and the signal-to-noise threshold with hearing aid (r = 0.38). These differences in the correlation coefficient indicate that the impairment of speech perception in noise when using a hearing aid is obviously due to the deterioration of the signal-to-noise threshold induced by the hearing loss rather than to the discrimination loss per se.     

Reconsidering the concept of the aided threshold for nonlinear hearing AIDS

The aided threshold (and functional gain) has been discussed in the context of linear hearing aids since the early 1960s. The use of nonlinear hearing aids, however, could change the meaningfulness of this verification tool because of their unique characteristics. The interpretation of the aided threshold (and functional gain) as it pertains to linear and nonlinear hearing aids is reviewed. Also discussed are the ideas of an optimal aided threshold, factors that may affect its magnitude, and a comparison between functional gain and insertion gain measures. Finally, how to improve the accuracy of the aided thresholds (and functional gain) through the use of in-situ unaided threshold measurements is discussed.