摘要:

This paper presents the derivation of a procedure for prescribing the saturation sound pressure level (SSPL) of hearing aids. The procedure is designed to be used with either measured values of loudness discomfort level(LDL) or with hearing threshold values alone. SSPL needs to be low enough to prevent the hearing aid from causing loudness discomfort to the aid wearer but high enough to prevent the hearing aid from being excessively saturated by speech. The maximum SSPL likely to be acceptable can be predicted by measuring LDL or by estimating LDL from hearing thresholds. The minimum SSPL likely to be acceptable can be predicted by calculating, for any particular hearing loss, the amount of gain likely to be needed and hence the SSPL needed if the speech input signal is continuous discourse at an overall level of 75 dB SPL. The midpoint between the minimum and maximum acceptable SSPL values is defined as the optimal or prescribed SSPL, and the three frequency average (3FA; 500, 1000, and 2000 Hz) value of this can be predicted from the 3FA hearing thresholds. Alternatively, the SSPL prescription at each frequency can be prescribed on the basis of the hearing aid gain at each frequency. For either method, the SSPL prescription needs to be increased for people with a conductive component to their hearing losses. The SSPL prescription, when referred to a 2-cc coupler, needs to be decreased for infants, for deeply inserted hearing aids, for multichannel hearing aids that limit SSPL separately in each band, and possibly for nonlinear hearing aids. The 3FA SSPL prescribed for persons with a sensorineural hearing loss increases linearly from 89 dB SPL for normal hearing to 107 dB SPL for a person with a 60 dB HL 3FA loss, and then linearly again to 139 dB SPL for a person with a 120 dB HL 3FA loss. The procedure predicts that the acceptable range of SSPLs is very wide for people with mild losses but is vanishingly small for people with profound losses.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:The primary aim of this study is to evaluate the accuracy of a new procedure for selecting the saturation sound pressure level (SSPL) of hearing aids. Secondary aims are to investigate what limits the minimum SSPL that is acceptable to clients and whether the type of limiting (peak clipping or compression limiting) affects the SSPL required.Design:The study comprised two experiments. In the first, subjects increased the SSPL of a laboratory master hearing aid until they experienced loudness discomfort and decreased it until the sound became less acceptable in some way. In the second study, subjects wore multi-memory programmable hearing aids in their own environments and reported which of the two programs, differing only in SSPL setting, provided the more acceptable sound quality and comfort.Results:The theoretical procedure being investigated prescribed SSPLs that were within the acceptable range for 86% of the subjects in the laboratory study and for 63% of the subjects in the field experiment. On average, the theoretical predictions were neither too high nor too low. Incorporating individual measurements of loudness discomfort level into the prescription formula increased accuracy by such a small amount that it was not considered worthwhile. For a compression limiting hearing aid, the first thing that subjects noticed as SSPL was reduced was inadequate loudness. For the peak clipping hearing aid, however, both inadequate loudness and perception of distortion limited the acceptable SSPL range.Conclusion:The theoretical procedure provides a good initial prescription of three frequency average SSPL, but it is still essential to evaluate the fitting and, if necessary, fine tune the individual's hearing aid. Compression limiting hearing aids can have slightly lower SSPL settings than peak clipping hearing aids for the same acceptability.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:The objective of this investigation was to compare real and perceived benefit for two currently marketed digital hearing aids, the Oticon DigiFocus™ and the Widex Senso™. The hearing aids have different philosophies of design and fitting strategies; as a result, it was hypothesized that there would be performance differences.Design:Twenty subjects with documented sensorineural hearing losses were fit with each of the two digital hearing aids. After 4 wk of use with each hearing aid, a battery of objective and subjective tests was completed to assess hearing aid benefit.Results:No significant differences were found between the hearing aids as revealed by the objective testing of speech recognition and self-report inventories of hearing aid benefit. The DigiFocus™ was shown by real ear measurements to provide more high-frequency gain than the Senso™. The Widex Senso™ was preferred by 13 of the 20 subjects (seven of 10 of the new hearing aid users). This may be explained, in part, by the increased high-frequency gain provided by the Oticon DigiFocus™, which was perceived as having greater "harshness."Conclusions:Based on the results of this investigation, neither hearing aid processor was shown to be superior to the other. In addition, the least amount of objective benefit was shown in the presence of background noise.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To investigate whether the evoked potential to a complex naturally produced speech syllable could be decomposed to reflect the contributions of the acoustic events contained in the constituent phonemes.Design:Auditory cortical evoked potentials N1 and P2 were obtained in eight adults with normal hearing. Three naturally produced speech stimuli were used: 1) the syllable [sei]; 2) the sibilant [s], extracted from the syllable; 3) the vowel [ei] extracted from the syllable. The isolated sibilant and vowel preserved the same time relationships to the sampling window as they did in the complete syllable. Evoked potentials were collected at Fz, Cz, Pz, A1, and A2, referenced to the nose.Results:In the group mean waveforms, clear responses were observed to both the sibilant and the isolated vowel. Although the response to the [s] was weaker than that to [ei], both had N1 and P2 components with latencies, in relation to sound onset, appropriate to cortical onset potentials. The vowel onset response was preserved in the response to the complete syllable though with reduced amplitude. This pattern was observable in six of the eight waveforms from individual subjects.Conclusions:It seems likely that the response to [ei] within the complete syllable reflects changes of cortical activation caused by amplitude or spectral change at the transition from consonant to vowel. The change from aperiodic to periodic stimulation may also produce changes in cortical activation that contribute to the observed response. Whatever the mechanism, the important conclusion is that the auditory cortical evoked potential to complex, time-varying speech waveforms can reflect features of the underlying acoustic patterns. Such potentials may have value in the evaluation of speech perception capacity in young hearing-impaired children.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objectives:The study was designed to assess the effects of background noise level on the detection and localization of speech.Design:The phrase "Where is this?" was presented either in quiet or in a diffuse noise field, through loudspeakers arranged in a 360° azimuth array. The noise conditions included 11 signal to noise ratios (SNRs) ranging from - 18 dB SNR to + 12 dB SNR in 3 dB increments. Seventeen normal-hearing subjects, aged 18 to 29, participated in the study.Results:Results revealed that in all listening conditions the signal was most easily detected when presented through a loudspeaker positioned at 90° or 270° azimuth. Although the actual level for 50% detection varied as a function of loudspeaker location and SNR, 85% and 100% of all presentations of the signal were detected at -9 dB and -6 dB SNR, respectively. Localization accuracy improved as the SNR increased, ranging from 18% accuracy at -18 dB SNR to 89% at +12 dB SNR. Localization accuracy in quiet was 95%. The data are discussed in reference to patterns of responses at each loudspeaker location.Conclusions:Detection of the target signal deteriorated as background noise level increased and was dependent on the source location of the incoming signal, as expected. Localization accuracy of the target signal was highly dependent on the SNR and spatial location of the signal source. Detection and localization accuracy data were found to be repeatable across test sessions and response patterns were found to be symmetrical on the right and left sides of the horizontal plane.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To compare how children who use either cochlear implants (CIs) or hearing aids (HAs) express English inflectional morphemes during conversation, i.e., with voice, with sign, or with both. A secondary objective was to investigate the relationship between morpheme use in pediatric CI users and their speech perception skills, length of experience with the device, and accuracy of phoneme production.Design:Group 1 consisted of 25 children who used CIs, and Group 2 consisted of 13 children who used HAs. All children were prelingually deafened and all used simultaneous communication. A 12 minute spontaneous conversation was elicited, transcribed and coded. Between group comparisons were performed to evaluate differences in modality and number of morphemes used. Additionally, use of morpheme endings was related to length of CI experience, accuracy of phoneme production, and closed-set speech recognition performance.Results:Children who had CI experience produced significantly more English inflected morphemes than children in the HA group. CI participants also expressed the inflected endings by using voice-only mode 91% of the time, whereas HA participants used voice-only mode 1% of the time. In the CI group, a strong relationship was found between number of morpheme endings used and speech recognition scores, length of CI experience and accuracy of phoneme production. The results of this study indicate that input from the CI facilitates children's ability to perceive and comprehend bound morphemes.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:The objective of this study was to identify individual sources of noise and their contribution to the overall noise that influences valid measurement of otoacoustic emissions in neonates. The hypothesis was that careful selection of eliciting signals and signal processing parameters, unique analysis of measured results, and control of certain subject characteristics would allow isolation of these individual noise sources and determine their relative influence.Design:Eliciting signal parameters were optimized and held constant to minimize equipment noise. Analysis of noise floors in relation to signal level was used to identify equipment-related noise associated with changes in signal parameters. Analysis of noise floor distributions was used to determine whether environmental noise entered the measurements via inadequate coupling of the probe to the ear. The acoustic characteristics of the middle ear were varied via subject selection to determine the influence of middle-ear characteristics on noise floor levels.Results:The two sources of noise associated with the measurement equipment need not contribute to the noise floor for biologically relevant otoacoustic emissions measurements (eliciting signal levels between 30 and 75 dB SPL). Of the two pathways identified for environmental noise, the pathway resulting from an inadequate seal between the probe and the ear canal can be eliminated. One of the two sources of noise related to the subject, noise resulting from biologic activity unrelated to the ear can be minimized. However, the remaining factor, the status of the middle ear, has been shown to contribute as much as 6 dB to the overall noise floor.Conclusions:Careful selection of signal parameters and additional data analyses and procedural variables can isolate or control several sources of noise that influence distortion product otoacoustic emission measurements in neonates. Tight coupling between the probe unit and the external ear canal should be maintained for all measurements. Middle ear abnormalities can increase noise floors up to 6 dB.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We compared population-based prevalence rates of unilateral hearing loss among African-American, Cuban-American, Mexican-American, Puerto Rican, and non-Hispanic White children 6 to 19 yr of age. The prevalence (per thousand) of overall hearing loss (average decibel HTL >30) ranged from 6.4 in Mexican-Americans to 12.3 in Cuban-Americans. The prevalence of moderate to profound unilateral hearing loss (average decibel HTL >50) range from 0.0 in Cuban-Americans to 5.2 in Puerto Ricans. No statistically significant age or gender differences were found within any of the ethnic groups. Among these five ethnic groups, it is estimated that approximately 391,000 school-aged children in the United States have unilateral hearing loss.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID