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PubMedDate not supplied

Speech intelligibility in noise with fast compression hearing aids.

The effect of fast (syllabic) compression with overshoot reduction was studied in moderately hearing-impaired and in severely hearing-impaired listeners in quiet and in noisy situations. A test battery of daily masking noises was selected using multidimensional scaling techniques. Four relevant noises were selected: a multi-talker babble, the noise in an industrial plant, in a printing office and a city-noise background. The speech measurements show that only selected patients benefit from syllabic compression, i.e. listeners with a poor speech discrimination score. The effect in noisy surroundings was tested at the critical signal-to-noise ratio of each patient, showing whether they benefited from compression in the most critical condition or not. It turns out that the effect depends largely on the speech discrimination score and the modulation of the noise signal. When the speech discrimination score is good, compression tends to impair the results. When the speech discrimination score is poor, compression helps if the noise is modulated.

Audiometry, Pure-Tone↗
PubMed1997

Speech intelligibility as a function of the number of channels of stimulation for signal processors using sine-wave and noise-band outputs.

Vowels, consonants, and sentences were processed through software emulations of cochlear-implant signal processors with 2-9 output channels. The signals were then presented, as either the sum of sine waves at the center of the channels or as the sum of noise bands the width of the channels, to normal-hearing listeners for identification. The results indicate, as previous investigations have suggested, that high levels of speech understanding can be obtained using signal processors with a small number of channels. The number of channels needed for high levels of performance varied with the nature of the test material. For the most difficult material--vowels produced by men, women, and girls--no statistically significant differences in performance were observed when the number of channels was increased beyond 8. For the least difficult material--sentences--no statistically significant differences in performance were observed when the number of channels was increased beyond 5. The nature of the output signal, noise bands or sine waves, made only a small difference in performance. The mechanism mediating the high levels of speech recognition achieved with only few channels of stimulation may be the same one that mediates the recognition of signals produced by speakers with a high fundamental frequency, i.e., the levels of adjacent channels are used to determine the frequency of the input signal. The results of an experiment in which frequency information was altered but temporal information was not altered indicates that vowel recognition is based on information in the frequency domain even when the number of channels of stimulation is small.

Adult↗
PubMed2002

A test to measure subjective and objective speech intelligibility.

Measurement of hearing aid outcome is particularly difficult because there are numerous dimensions to consider (e.g., performance, satisfaction, benefit). Often there are discrepancies between scores in these dimensions. It is difficult to reconcile these discrepancies because the materials and formats used to measure each dimension are so very different. We report data obtained with an outcome measure that examines both objective and subjective dimensions with the same test format and materials and gives results in the same unit of measurement (signal-to-noise ratio). Two variables are measured: a "performance" speech reception threshold and a "perceptual" speech reception threshold. The signal-to-noise ratio difference between these is computed to determine the perceptual-performance discrepancy (PPDIS). The results showed that, on average, 48 percent of the variance in subjective ratings of a hearing aid could be explained by a combination of the performance speech reception threshold and the PPDIS. These findings suggest that the measure is potentially a valuable clinical tool.

Aged↗
PubMed2002

Speech intelligibility with bilateral bone-anchored hearing aids: the Birmingham experience.

The Birmingham bone-anchored hearing aid (BAHA) programme, since its inception in 1988, has fitted more than 300 patients with unilateral bone-anchored hearing aids. Recently, some of the patients who benefited extremely well with unilateral aids applied for bilateral amplification. To date, 15 patients have been fitted with bilateral BAHAs. The benefits of bilateral amplification have been compared to unilateral amplification in 11 of these patients who have used their second BAHA for 12 months or longer. Following a subjective analysis in the form of comprehensive questionnaires, objective testing was undertaken to assess specific issues such as 'speech recognition in quiet', 'speech recognition in noise' and a modified 'speech-in-simulated-party-noise' (Plomp) test. 'Speech in quiet' testing revealed a 100 per cent score with both unilateral and bilateral BAHAs. With 'speech in noise' all 11 patients scored marginally better with bilateral aids compared to best unilateral responses. The modified Plomp test demonstrated that bilateral BAHAs provided maximum flexibility when the origin of noise cannot be controlled as in day-to-day situations. In this small case series the results are positive and are comparable to the experience of the Nijmegen BAHA group.

Adult↗
PubMed2002

Efficient adaptive procedures for threshold and concurrent slope estimates for psychophysics and speech intelligibility tests.

The minimum standard deviations achievable for concurrent estimates of thresholds and psychometric function slopes as well as the optimal target values for adaptive procedures are calculated as functions of stimulus level and track length on the basis of the binomial theory. The optimum pair of targets for a concurrent estimate is found at the correct response probabilities p1 = 0.19 and p2 = 0.81 for the logistic psychometric function. An adaptive procedure that converges at these optimal targets is introduced and tested with Monte Carlo simulations. The efficiency increases rapidly when each subject's response consists of more than one statistically independent Bernoulli trial. Sentence intelligibility tests provide more than one Bernoulli trial per sentence when each word is scored separately. The number of within-sentence trials can be quantified by the j factor [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84, 101-114 (1988)]. The adaptive procedure was evaluated with 10 normal-hearing and 11 hearing-impaired listeners using two German sentence tests that differ in j factors. The expected advantage of the sentence test with the higher j factor was not observed, possibly due to training effects. Hence, the number of sentences required for a reliable speech reception threshold (approximately 1 dB standard deviation) concurrently with a slope estimate (approximately 20%-30% relative standard deviation) is at least N = 30 if word scoring for short, meaningful sentences (j approximately 2) is performed.

Adult↗
PubMed1996

Fitting hearing aids to individual loudness-perception measures.

OBJECTIVE: The purpose of this study was to compare the prescribed gain, compression ratios, compression thresholds, and the relative predicted speech intelligibility (Speech Intelligibility Index [SII], American National Standards Institute 3.79, proposed) provided by four strategies proposed for selecting hearing aid parameters for low-threshold compression hearing instruments and by a traditional threshold-based hearing aid fitting procedure. The strategies used were Desired Sensation Level Input/Output (DSLTM[i/o]; Cornelisse, Seewald, & Jamieson, 1994), Visual Input-Output Locator Algorithm (VIOLA; Cox, 1994), FIG6 strategy (Killion, Reference Note 2), Ricketts and Bentler strategy (RAB), and a threshold-based hearing aid fitting procedure (National Acoustics Laboratories-Revised [NAL-R]; Byrne & Dillion, 1986). These new strategies have been suggested as alternatives to threshold-based strategies, which do not provide the varying amounts of target gain, as a function of input level, necessary to fit low-threshold compression hearing aids. DESIGN: The electroacoustic prescriptions and the predicted speech intelligibility were calculated across all five fitting strategies for 20 subjects. The threshold and loudness growth information used for each fitting was reported previously (Ricketts & Bentler, in press). RESULTS: Comparison across prescriptions revealed that the NAL-R strategy (due to the linear gain provided) prescribed the least gain for low-level inputs and the greatest gain for high-level inputs. Gain comparisons across fitting by loudness (FBL) strategies revealed a more shallow frequency response slope for strategies that require individual measures of loudness growth (RAB, VIOLA) in comparison with strategies that assumed average data (FIG6, DSLTM[i/o]). SII results revealed greater predicted speech intelligibility for the FIG6 and the DSLTM[i/o] compared with the NAL-R, RAB, and VIOLA. These differences were most apparent in noise backgrounds and least evident when loudness differences were minimized. CONCLUSIONS: It appears that differences in SII scores across the FBL fitting strategies are due, in part, to differences in the loudness of the output signal. It is assumed that differences in high-frequency shaping may also be a factor. These data do not appear to support the use of additional clinical time to obtain individual loudness growth measures. However, due to the fact that SII results are based on average performance, it is difficult to predict whether differences across these fitting strategies would be realized in actual measures of speech intelligibility or sound quality on an individual basis.

Correction of Hearing Impairment↗
PubMed2005

A clinical perspective on cochlear dead regions: intelligibility of speech and subjective hearing aid benefit.

Using the threshold equalizing noise (TEN) test, 49 subjects with at least two pure-tone thresholds per ear greater than 50 dB HL and none greater than 80 dB HL were evaluated for the presence or absence of dead regions. The purpose of this study was to (1) assess the prevalence of cochlear dead regions in this clinical population, (2) measure whether listeners with dead regions performed differently than listeners without dead regions on a speech intelligibility in noise test, and (3) determine whether cochlear dead regions are associated with reduced subjective hearing aid performance. The results showed that (1) twenty-nine percent of the subjects tested positive for dead regions, (2) listeners with dead regions had poorer sentence understanding in noise than listeners without dead regions and (3) listeners with dead regions perceived poorer subjective hearing aid performance in listening environments with reverberation or background noise as compared to those without dead regions.

Adult↗
PubMed1983

Airflow characteristics of fricative consonants produced by normally hearing and hearing-impaired speakers.

The purpose of this study was to investigate the rates of airflow for fricative consonants produced by normally hearing speakers and by hearing-impaired speakers who varied in degree of hearing loss and speech intelligibility. Subjects consisted of 20 normally hearing adults (10 men and 10 women), 20 moderately-to-severely hearing-impaired adults with intelligible speech (10 men and 10 women), and 20 profoundly hearing-impaired adults with semi-intelligible speech (10 men and 10 women). Average airflow rates were obtained for the fricatives /s/, /z/, /f/, and /v/ in CV and VCV syllables. In general, it was found that normally hearing, intelligible hearing-impaired, and some semi-intelligible hearing-impaired speakers produced voiceless fricatives with substantially greater airflow rates than they produced voiced cognates. The data also revealed that both male and female semi-intelligible hearing-impaired speakers produced fricatives in the CV context with greater amounts of airflow and fricatives in the VCV environment with less airflow than did the normally hearing and intelligible hearing-impaired speakers. Further, the male and female semi-intelligible hearing-impaired speakers failed to demonstrate the trend, as exhibited by the other speakers, for lingua-alveolar fricatives to be produced with greater air flow than the labiodental fricatives. The data from this investigation provide additional evidence to support the assumption that some hearing-impaired speakers fail to control and coordinate the biomechanical aspects of speech properly.

Adult↗
PubMed2001

Effects of low-pass filtering on the intelligibility of speech in quiet for people with and without dead regions at high frequencies.

A dead region is a region of the cochlea where there are no functioning inner hair cells (IHCs) and/or neurons; it can be characterized in terms of the characteristic frequencies of the IHCs bordering that region. We examined the effect of high-frequency amplification on speech perception for subjects with high-frequency hearing loss with and without dead regions. The limits of any dead regions were defined by measuring psychophysical tuning curves and were confirmed using the TEN test described in Moore et al. [Br. J. Audiol. 34, 205-224 (2000)]. The speech stimuli were vowel-consonant-vowel (VCV) nonsense syllables, using one of three vowels (/i/, /a/, and /u/) and 21 different consonants. In a baseline condition, subjects were tested using broadband stimuli with a nominal input level of 65 dB SPL. Prior to presentation via Sennheiser HD580 earphones, the stimuli were subjected to the frequency-gain characteristic prescribed by the "Cambridge" formula, which is intended to give speech at 65 dB SPL the same overall loudness as for a normal listener, and to make the average loudness of the speech the same for each critical band over the frequency range important for speech intelligibility (in a listener without a dead region). The stimuli for all other conditions were initially subjected to this same frequency-gain characteristic. Then, the speech was low-pass filtered with various cutoff frequencies. For subjects without dead regions, performance generally improved progressively with increasing cutoff frequency. This indicates that they benefited from high-frequency information. For subjects with dead regions, two patterns of performance were observed. For most subjects, performance improved with increasing cutoff frequency until the cutoff frequency was somewhat above the estimated edge frequency of the dead region, but hardly changed with further increases. For a few subjects, performance initially improved with increasing cutoff frequency and then worsened with further increases, although the worsening was significant only for one subject. The results have important implications for the fitting of hearing aids.

Aged↗
PubMed2002

Speech and swallowing function after reconstruction with a radial forearm free flap or a pectoralis major flap for tongue cancer.

BACKGROUND AND PURPOSE: The tongue plays a more significant role in English than in Mandarin, both in apical-palatal consonant production and tense-lax distinction. Theoretically, the same surgical intervention may produce a less significant impact on postoperative Mandarin production. The impact of tongue reconstruction on Mandarin articulation has not been reported. This study compared the tongue function outcome obtained using two methods of tongue reconstruction, radial forearm free flap transfer and pectoralis major flap transfer. METHODS: Twenty-five patients with carcinoma of the tongue underwent tumor resection. The surgical defects were reconstructed using a pectoralis major flap in six patients and a radial forearm flap in 19 patients. Swallowing and speech function were evaluated 6 months to 5 years after the reconstruction. Speech intelligibility and a Mandarin articulation test were used to evaluate the articulation proficiency before and after surgery. Clinical evaluation of deglutition included a questionnaire on dietary habits and a swallowing rating of 1 to 7. RESULTS: Clinical evaluation showed that patients with free flap reconstruction had more intelligible speech (p = 0.014) even after total glossectomy. Assessment of data obtained by clinical questionnaire showed no significant difference between the two groups in swallowing function. Motility due to flap pliability increased speech intelligibility but had little effect on swallowing function. CONCLUSION: Our results suggest that radial forearm flap transfer is better than pectoralis major flap transfer in preserving speech function and that there is no significant difference between the two methods of reconstruction in their impact on swallowing function.

Deglutition↗
PubMed1993

Comparison of a programmable 3-channel compression hearing system with single-channel AGC instruments.

A commercially available programmable BTE hearing aid with 3-channel AGC (Siemens, Triton 3000) was compared to the subjects' own single-channel compression aids in a group of experienced hearing aid wearers. Two cross-over frequencies, three AGC onset levels, and three channel amplifications were programmable. The maximum output level was controlled by conventional peak clipping. The frequency response of the multichannel system was matched to the individuals' own aids which had been fitted in the two years prior to this study. Frequency response shaping was accomplished by real ear measurement monitoring. The performance of the hearing instruments was measured by (1) speech audiometry in noise and (2) subjective judgement of sound quality and speech intelligibility. Speech recognition was tested using rhyme test material in noise in a group of 10 subjects with sloping high-frequency hearing loss as well as in a group of 16 individuals with nearly flat audiograms. In both subgroups speech recognition scores (S/N: -5 to 15 dB) were 7 to 20% higher for the 3-channel AGC device compared to the single-channel AGC instruments. This finding is equivalent to an improvement of the S/N ratio of about 7 dB for the user. The results of the subjective judgements were similar for both subgroups. Sound quality and speech intelligibility were mostly rated as "very good" or "good" on a 5-point-scale. The subjects were also asked to compare the performance of their own hearing aids with the 3-channel AGC instrument; the latter generally turned out to be preferable.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1997

Effects of fast-acting high-frequency compression on the intelligibility of speech in steady and fluctuating background sounds.

This study examines whether speech intelligibility in background sounds can be improved for persons with loudness recruitment by the use of fast-acting compression applied at high frequencies, when the overall level of the sounds is held constant by means of a slow-acting automatic gain control (AGC) system and when appropriate frequency-response shaping is applied. Two types of fast-acting compression were used in the high-frequency channel of a two-channel system: a compression limiter with a 10:1 compression ratio and with a compression threshold about 9 dB below the peak level of the signal in the high-frequency channel; and a wide dynamic range compressor with a 2:1 compression ratio and with the compression threshold about 24 dB below the peak level of the signal in the high-frequency channel. A condition with linear processing in the high-frequency channel was also used. Speech reception thresholds (SRTs) were measured for two background sounds: a steady speech-shaped noise and a single male talker. All subjects had moderate-to-severe sensorineural hearing loss. Three different types of speech material were used: the adaptive sentence lists (ASL), the Bamford-Kowal-Bench (BKB) sentence lists and the Boothroyd word lists. For the steady background noise, the compression generally led to poorer performance than for the linear condition, although the deleterious effect was only significant for the 10:1 compression ratio. For the background of a single talker, the compression had no significant effect except for the ASL sentences, where the 10:1 compression gave significantly better performance than the linear condition. Overall, the results did not show any clear benefits of the fast-acting compression, possibly because the slow-acting AGC allowed the use of gains in the linear condition that were markedly higher than would normally be used with linear hearing aids.

Adult↗
PubMed1994

Intelligibility of tracheoesophageal speech among naive listeners.

Tracheoesophageal (TE) speech is now the most common method of voice rehabilitation after total laryngectomy. The speech intelligibility of laryngectomees who use TE speech as their primary mode of communication was evaluated by 20 "naive" listeners. Two speech intelligibility tests were administered using phonetically balanced rhyming words or lists of spondee words. The overall intelligibility for the group of laryngectomees was 76%, with a wide range of variability among the individual TE speakers. We concluded that TE speech is significantly less intelligible to naive listeners than normal laryngeal speech; further refinement of voice rehabilitation for laryngectomees is needed.

Female↗