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R S Tyler

Publications and source records attributed to R S Tyler.

107 records · Page 6Linked to original sources
PubMed1983

Difficulties experienced by hearing-aid candidates and hearing-aid users.

Responses to an open-ended questionnaire were obtained from 250 hearing-aid candidates who had never worn a hearing aid and from 250 experienced hearing-aid users. The questionnaire stated 'Please make a list of the difficulties which you have as a result of your hearing loss.' The responses were divided into six major categories. The hearing-aid candidates reported more problems than the experienced users in the categories of (a) understanding speech where speechreading would normally be used (92% versus 81%), and (b) understanding speech where speechreading would normally not be used (51% versus 43%). A similar number of respondents in both groups reported problems in the categories of (c) personal difficulties (11%), (d) audiological or medical difficulties (18%), and (e) difficulties associated with environmental sounds (34%). Thirty-five per cent of the hearing-aid users reported (f) difficulties associated with their hearing aids. The most frequently reported specific difficulty in both groups was watching television (47% of the candidates and 37% of the users). Twenty-one per cent in each group reported difficulty conversing on the telephone.

Adult↗
PubMed1982

Masking of pure tones by broad-band noise in cochlear-impaired listeners.

We measured masked thresholds for pulsed pure tone (5, 1.0, 2.0, and 4.0 kHz) in the presence of different levels of broad-band noise (nominally 0, 20, 40, and 60 dB/Hz). Several of the 16 cochlear-impaired listeners displayed masked thresholds that were considerably higher than those obtained from 10 normal listeners. At the 60 dB/hz noise level the correlation coefficients between thresholds in noise and thresholds in quiet were r = 36, .44, .63 and .64 for signal frequencies of .5, 1.0, 2.0, and 4.0 kHz, respectively. The growth of masking, as masker level was increased, was linear for the normal listeners but was disproportionate and nonlinear in some cochlear-impaired listeners. In these data and data from others studies, it is clear that thresholds in noise cannot be predicted from thresholds in quiet. Masked thresholds are related to other measures of frequency resolution and to speech intelligibility in noise, but it is argued that psychoacoustic tuning curves provide more direct measures of the auditory-filter characteristics.

Adult↗
PubMed1982

Frequency resolution and hearing loss.

Future scientific and diagnostic interest in frequency resolution requires an evaluation of the different methods that are available to measure it. We compared three methods: (1) pure-tone thresholds in broadband noise, (2) pure-tone thresholds in the presence of a fixed pure-tone masker and (3) psychoacoustical tuning curves. We additionally obtained estimates of temporal integration and of speech intelligibility in noise. Three subject groups were tested: 10 normals, 13 subjects with a noise-induced hearing loss and 18 subjects with a cochlear hearing loss but no history of noise exposure. Generally the three measures of frequency resolution show moderate agreement with each other. Poor frequency resolution is invariably associated with a pure-tone threshold loss. Temporal integration appears unrelated either to the pure-tone threshold loss or frequency resolution. Some of the measures of frequency resolution display significant correlation with speech intelligibility in noise. However, since both variables are correlated with pure-tone threshold loss the exact relationship between frequency resolution and speech intelligibility cannot be clearly established.

Adolescent↗
PubMed1981

Critical masking bands for sensorineural tinnitus.

The level of noise required to mask tinnitus was measured in 12 subjects with sensorineural tinnitus; the noise was centred on the estimated pitch of the tinnitus, and the overall level required to just mask the tinnitus was measured for masker bandwidths of 2.5, 10, 20, 30 and 50% of the noise centre-frequency. For four of the tinnitus subjects, masking functions were similar to those observed in normal-hearing subjects with a "simulated" tinnitus (15-dB Sensation Level, 4-kHz pure tone). The other eight tinnitus subjects, however, required masking levels that were either independent of masker bandwidth or showed anomalous changes in masker level as bandwidth was increased. These results suggest that certain masker bandwidths can be more efficient than others for the masking of tinnitus, and that masker characteristics deserve close attention in the design and fitting of tinnitus-masker instruments.

Acoustics↗
PubMed1980

Combination tones and unmasking.

Some important relationships between two auditory nonlinearities, unmasking and combination tone (CT) production, are described. An example of unmasking is provided by using a forward-masking paradigm where a baseline is first obtained by determining the threshold of a 2000 Hz signal preceded by a 2000 Hz masker. When a second tone (the suppressor) is then added concurrently with the masker, the signal can be easier to hear. At a suppressor level of 80 dB SPL, this unmasking occurs for suppressor frequencies around 2300 Hz. At a suppressor level of 55 dB SPL, the unmasking effect occurs at suppressor frequencies closer to the masker frequency. An example of CT production is provided by presenting two sinusoids (f1 and f2) as maskers in a forward-masking experiment. The threshold of the 2000 Hz signal is shown to decrease as f2/f1 is increased keeping 2f1 - f2 = 2000 Hz. This is consistent with the notion that the magnitude of the CR decreases as f2/f1 increases. We then provide evidence that CTs can produce ummasking effects similar to acoustic tones. Again a baseline was determined with a 2000 Hz signal amd masker (f1). Two higher-frequency sinusoids (f2 and f3) were added simultaneously to the masker, neither of which produced unmasking when presented individually. When 2f2 - f3 or f3 - f2 was approximately 2300 Hz, unmasking was observed. Next was explored 2f2 - f3 unmasking as a function of f3/f2, keeping 2f2 - f3 frequency fixed at 2300 Hz. As f3/f2 increases, the magnitude of the unmasking decreases. These CT unmasking effects suggest that the generation of CTs must be at the same site or peripheral to the site of suppression.

Acoustic Stimulation↗
PubMed1980

A comparison of manual methods for measuring hearing levels.

A comparison was made of three manual methods for measuring pure-tone sensitivity; one method is proposed by the Education Committee of the British Society of Audiology (BSA), the second method is recommended by the American Speech and Hearing Association (ASHA) and the third is a shortened version of the ASHA method. 9 normally-hearing and 5 hearing-impaired subjects from differing educational backgrounds were tested at 1.0 kHz a total of fifteen times on each of the methods. False-positive responses were noted throughout the testing and also in a 20-second time-out period. Each threshold run was timed and the subjects were asked to rate each threshold run on a 10-point scale for ease of the task. No significant differences among the three methods were found in their threshold estimates, standard deviations, number of false-positive responses, or subject preferences. The ASHA method took longer and required more tone presentations to establish threshold. The number of successive tone presentations to which the subject did not respond was also counted. The BSA method produced more, and longer silent intervals than the other two methods.

Adolescent↗
PubMed1979

Unmasking produced by combination tones.

This experiment investigated some interactions between combination tones (CT) and unmasking. Data were obtained from nine normal-hearing listeners in a forward-masking paradigm in which a 2000-Hz, 35-dB SPL masker preceded a 2000-Hz test signal. An adaptive, three-interval forced-choice procedure was employed to estimate the threshold for the test signal. This measurement provided a baseline. When a second sinusoid, the suppressor, of variable frequency and 55 dB SPL was presented concurrently with the masker, the amount of masking could be less than in the baseline condition. This two-tone unmasking was observed when the suppressor was approximately 2300 Hz. In the cubic difference tone (CDT) condition, two higher-frequency sinusoids of 80 dB SPL (with the lower frequency fixed at 2800 Hz) were added to the masker. In the difference tone (DT) condition, two higher-frequency sinusoids of 100 dB SPL (with the lower frequency fixed at 3500 Hz) were added to the masker. None of these sinusoids produced unmasking when presented individually, but when the CDT and DT were approximately 2300 Hz, unmasking was observed. The unmasking produced by the CTs was similar in its frequency characteristics to that of the single, suppressor tone. These results indicate that unmasking can be produced by CTs, just as if CTs were present in the stimulus. These data indirectly support the notion that CTs may be present in the form of traveling waves propagated along the basilar membrane.

Acoustic Stimulation↗
PubMedDate not supplied

Audiological results with two single channel cochlear implants.

We tested six patients with single channel cochlear implants on several tests from the Minimal Auditory Capabilities battery and the Iowa Cochlear Implant Tests. All patients were able to discriminate some everyday sounds and to identify the number of syllables in the words presented. Five patients were able to identify speaker sex reliably. Surprisingly, some patients had difficulty discriminating between a modulated noise and a voice or between a question and a statement or identifying the accented word in a sentence. On several audiovisual tests, an improvement was observed for the sound plus vision condition compared to the vision only condition. This was particularly true for sentence tests, but was not uniform across patients or across tests.

Adult↗
PubMedDate not supplied

Performance of adult Ineraid and Nucleus cochlear implant patients after 3.5 years of use.

Forty-two postlingually deafened adult patients, 21 with a formant extraction version of the Nucleus cochlear implant and 21 with the Ineraid cochlear implant (analog processing), were evaluated on a series of speech perception tests after using their implants for about 3.5 years. A wide range of performance was observed across patients for both devices. All but 4 patients showed an enhancement in their lipreading ability with the implant. Word recognition averaged about 14-19% correct, and word recognition in sentences averaged about 43-49% correct for the two implant groups. Average performance was superior with the Ineraid implant on consonant recognition in noise. An information transmission analysis suggested that vowel perception was influenced by first- and third-formant frequency for the Nucleus, and first-formant and fundamental frequency for the Ineraid patients. It appeared that the Ineraid device was more effective, on average, at conveying information about consonant nasality and frication. For consonant perception, nasality and frication contributed most to the total information transmitted for both implant types. Both devices had difficulty conveying information about vowel second-formant frequency and consonant place information. These scores at 3.5 years are substantially elevated from preoperative performance and, overall, the patients clearly benefit from their implant.

Adult↗
PubMedDate not supplied

Musical backgrounds, listening habits, and aesthetic enjoyment of adult cochlear implant recipients.

This paper describes the listening habits and musical enjoyment of postlingually deafened adults who use cochlear implants. Sixty-five implant recipients (35 females, 30 males) participated in a survey containing questions about musical background, prior involvement in music, and audiologic success with the implant in various listening circumstances. Responses were correlated with measures of cognition and speech recognition. Sixty-seven implant recipients completed daily diaries (7 consecutive days) in which they reported hours spent in specific music activities. Results indicate a wide range of success with music. In general, people enjoy music less postimplantation than prior to hearing loss. Musical enjoyment is influenced by the listening environment (e.g., a quiet room) and features of the music.

Adult↗
PubMedDate not supplied

An international test battery for cochlear implant patients.

It is now clear that cochlear implants can provide useful hearing for profoundly deaf adults, and that multichannel devices give the brain more information than most single-channel devices. We are in a dilemma as to how to compare the many multichannel devices, because of the language barrier. Virtually no multichannel wearer is equally testable in two, let alone more languages. A test battery that abstracts beyond language is proposed, utilizing carefully constructed non-linguistic syllables and its development underway.

Cochlear Implants↗
PubMedDate not supplied

Auditory brainstem and middle latency responses. I. Effect of response filtering and waveform identification. II. Threshold responses to a 500-HZ tone pip.

Auditory brainstem (ABR) and middle latency responses (MLR) were recorded for ten normal subjects. Changes in wave latency were recorded with high- and low-pass filtering using Butterworth filters with standard phase-shift characteristics. When an open filter (15-3,000 HZ) was used, waves IV, V and VI of the ABR were superimposed on wave P phi of the MLR. A positive (P) wave was recorded in the trough of wave Na as the high-frequency cutoff of the recording bandpass (15-100 Hz) was raised above 100 Hz. Wave P divided Na into two parts. The first trough was the slow-negative response and the second was Na2. The origin of the P wave is unclear but may represent a muscle potential. Because of previous inconsistencies in the waveform identification used with these recording techniques, the authors present a modified method of classification which accommodates changes in waveform appearance that occur with different response filtering. The thresholds for various waves of the auditory brainstem (ABR) or middle latency response (MLR) were determined to a 500-Hz tone pip in ten normal listeners in a variety of recording filter bandwidths. Wave V (recording filters 100-3,000 Hz) had a threshold of 26 dB nHL. Wave SN (30-3,000 Hz) had a threshold of 18 dB nHL. Waves Na, Pa and Nb had thresholds of 10 to 11 dB nHL. The threshold for waves Na, Pa and Nb were unaffected by changing the recording bandpass from 15-3,000 Hz. The ABR amplitude increased when the recording filter's low-frequency cutoff was lowered from 100 to 15 Hz (high frequency cutoff, 3,000 Hz). This augmentation is probably due to the inclusion of the lower frequency energy of wave P phi. Lowering the recording filters high-frequency cutoff from 3,000 to 100 Hz (low-frequency cutoff, 15 Hz) resulted in exclusion of the higher frequency ABR but did not elevate response threshold. In all listeners tested, the MLR had a lower threshold than the ABR to a 500-Hz tone pip. It is suggested that the MLR has good potential for use in evaluation of low-frequency threshold.

Acoustic Stimulation↗