Sigfrid D. Soli

Development of the Hearing In Noise Test for the measurement of speech reception thresholds in quiet and in noise

A large set of sentence materials, chosen for their uniformity in length and representation of natural speech, has been developed for the measurement of sentence speech reception thresholds (sSRTs). The mean-squared level of each digitally recorded sentence was adjusted to equate intelligibility when presented in spectrally matched noise to normal-hearing listeners. These materials were cast into 25 phonemically balanced lists of ten sentences for adaptive measurement of sentence sSRTs. The 95% confidence interval for these measurements is +/- 2.98 dB for sSRTs in quiet and +/- 2.41 dB for sSRTs in noise, as defined by the variability of repeated measures with different lists. Average sSRTs in quiet were 23.91 dB(A). Average sSRTs in 72 dB(A) noise were 69.08 dB(A), or -2.92 dB signal/noise ratio. Low-pass filtering increased sSRTs slightly in quiet and noise as the 4- and 8-kHz octave bands were eliminated. Much larger increases in SRT occurred when the 2-kHz octave band was eliminated, and bandwidth dropped below 2.5 kHz. Reliability was not degraded substantially until bandwidth dropped below 2.5 kHz. The statistical reliability and efficiency of the test suit it to practical applications in which measures of speech intelligibility are required.

Treatment of mixed hearing losses via implantation of a vibratory transducer on the round window

Early clinical findings are reported for subjects implanted with the Vibrant Med-El Soundbridge® (VSB) device. The present criteria for the VSB, limiting its application to patients with normal middle ear function, have been extended to include patients with ossicular chain defects. Seven patients with severe mixed hearing loss were implanted with the transducer placed onto the round window. All had undergone previous surgery: six had multiple ossiculoplasties, and one had the VSB crimped on the incus with unsuccessful results. Round window implantation bypasses the normal conductive path and provides amplified input to the cochlea. Post-operative aided thresholds of 30 dB HL were achieved for most subjects, as compared with unaided thresholds ranging from 60–80 dB HL. Aided speech reception thresholds at 50% intelligibility were 50 dB HL, with most subjects reaching 100% intelligibility at conversational levels, while unaided thresholds averaged 80 dB HL, with only one subject reaching 100% intelligibility. These results suggest that round window implantation may offer a viable treatment option for individuals with severe mixed hearing losses who have undergone unsuccessful ossiculoplasties.

Importance of tonal envelope cues in Chinese speech recognition

Temporal waveform envelope cues provide significant information for English speech recognition, and, when combined with lip reading, could produce near‐perfect consonant identification performance [Van Tasell et al., 1152–1161 (1987)]. Tonal patterns are important for Chinese speech recognition and can be effectively conveyed by temporal envelope cues [D. H. Whalen and Y. Xu, Phonetics 49, 25–47 (1992)]. This study investigates whether tones can help Chinese‐speaking listeners use envelope cues more effectively than English listeners. The speech envelope was extracted from broad frequency bands and used to modulate a noise of the same bandwidth. Mandarin vowels, consonants, tones, and sentences were identified by ten native Chinese‐speaking listeners with 1, 2, 3, and 4 noise bands (or channels). The results showed that recognition of vowels, consonants and sentences increases dramatically with the number of channels, a pattern similar to that observed in English speech recognition. However, tones were co...

Transcranial Contralateral Cochlear Stimulation in Unilateral Deafness

OBJECTIVES: The purpose of this study is to evaluate the effectiveness of Bone Anchored Cochlear Stimulator (BAHA) in transcranial routing of signal by implanting the deaf ear. STUDY DESIGN AND SETTINGS: Eighteen patients with unilateral deafness were included in a multisite study. They had a 1-month pre-implantation trial with a contralateral routing of signal (CROS) hearing aid. Their performance with BAHA was compared with the CROS device using speech reception thresholds, speech recognition performance in noise, and the Abbreviated Profile Hearing Benefit and Single Sided Deafness questionnaires. RESULTS: Patients reported a significant improvement in speech intelligibility in noise and greater benefit from BAHA compared with CROS hearing aids. Patients were satisfied with the device and its impact on their quality of life. No major complications were reported. CONCLUSION AND SIGNIFICANCE: BAHA is effective in unilateral deafness. Auditory stimuli from the deaf side can be transmitted to the good ear, avoiding the limitations inherent in CROS amplification.

Second formants in fricatives: Acoustic consequences of fricative‐vowel coarticulation

Spectral analyses of the sibilant fricatives, [s, z, F, z], as spoken in isolation and in initial position before the vowels [a, i, u], were performed for a corpus of 80 utterances. The mean LPC spectra for five utterances of each fricative produced in each vowel context revealed reliable anticipatory vowel coarticulation effects present at least 30–60 ms before vowel onset in the form of spectral peaks affiliated with the second formant of the vowel. Peak frequencies were between 1.5 and 2 kHz and were approximately 100–300 Hz higher before the front vowel [i] than before the back vowels [a, u]. The presence of these peaks in the fricative spectra indicate that during the latter part of the fricative the constriction begins to open in anticipation of the vowel, and, as a consequence, second formant resonances are excited. The acoustic characteristics of these fricative formants varied as a function of vowel context due to differences in the anticipatory coarticulation of the vowel. Fricative place of con...

Development of the Mandarin Hearing In Noise Test (MHINT)

Objective: To develop two versions of the Mandarin Hearing In Noise Test (MHINT). These tests are adaptive tests that measure the reception threshold for sentences (RTSs) in quiet and in noise. The RTS is the presentation level at which half the sentences are correctly recognized. Design: Four studies were undertaken to (1) develop sentence materials, (2) equalize sentence difficulty, (3) create phonemically balanced sentence lists; and (4) evaluate within-list response variability, inter-list reliability, and produce normative data. A total of 137 native Mandarin (Putonghua) speaking subjects in Mainland China and 89 native Mandarin speakers in Taiwan participated. They had normal hearing thresholds at 25 dB HL or better. RTSs were measured under four headphone test conditions: Quiet, and in noise with noise originating from the 0 degree (Noise Front), 90 degrees to the right (Noise Right), and 90 degrees to the left (Noise Left). The speech originated from the front (0 degree) in all conditions. The noise level was fixed at 65 dBA, and the speech was varied adaptively to find the RTS. Results: Two versions of the test materials, consisting of 24, 20-sentence lists each in Mandarin spoken in the Mainland (the MHINT-M) and the dialect of Mandarin spoken in Taiwan (the MHINT-T), were created from two sets of 240 sentences containing 10 syllables per sentence. The mean Quiet RTS was 14.7 dBA, using the MHINT-M, and 19.4 dBA, using the MHINT-T. Using the MHINT-M, the mean RTS for Noise Front was –4.3 dB signal-to-noise ratio (SNR), –11.7 dB SNR for Noise Right, and –11.7 dB SNR for Noise Left. Using the MHINT-T, the Noise Front RTS was –4.0 dB SNR, –10.7 dB SNR for Noise Right, and –11.0 dB SNR for Noise Left. Results in noise are slightly better than those seen for the English HINT norms. Response variability within list was low, and inter-list reliability was high, indicating that consistent results can be obtained using any list. Confidence intervals are reported. Conclusions: The two versions of the MHINT are the first standardized Mandarin sentence speech intelligibility tests. Similar to other language versions of the HINT, the MHINT was developed using the same rationale as the English HINT, allowing norm-referenced results for the MHINT to be compared directly with results in other languages. The MHINT would benefit from further evaluation of its validity.

Method of signal processing for maintaining directional hearing with hearing aids

The insertion effects of hearing aids are determined and compensated to restore the ability to have directional hearing in individuals wearing hearing aids. In one aspect a method involves finding the ratio of the unaided head related transfer function to the aided head related transfer function and then designing a hearing aid filter that is the inverse of that derived insertion effect, thereby restoring the ability to hear interaural differences in aided systems both in level and in time of arrival to improve hearing in the presence of noise. The insertion effects can be derived either through frequency domain analyses, using the above-mentioned transfer function calculations and measurements, or in another aspect through time domain analyses, using optimal filter calculations and measurement obtained using a successive data acquisition system that is subsequently time aligned by recording trigger pulses with the data.

Assessment of speech intelligibility in noise with the Hearing in Noise Test

Assessment of speech intelligibility in noise in clinical settings, as well as in the laboratory, presents a wide variety of challenges. Developers of the hearing in noise test (HINT) have attempted to address these challenges through application of a number of methodological assumptions and procedures, and by constraining the type of speech materials used in the test. These assumptions and constraints have allowed the HINT to be developed in a number of several different languages and to provide comparable measures of speech intelligibility in noise for each language. This introductory paper discusses the challenges of assessing speech intelligibility in noise, the approach used with the HINT, and the implications of the assumptions and constraints when interpreting test results. Difficulty in measuring speech intelligibility in noise occurs, in large part, because of the many factors that influence intelligibility in noise. Each of these factors introduces a source of variability that can affect the measure. In the following paragraphs, we discuss each factor and describe the approach that has been used to address these factors in the development of the HINT. Our approach is motivated by the primary purpose for administering the HINT*to assess the effects of an individual’s hearing on their speech intelligibility in noise. These effects are assessed in two different ways with the HINT. One is a withinsubject, or relative, comparison of an individual’s speech intelligibility between two or more conditions (e.g. when using hearing aid A or hearing aid B). The other is a between-subjects comparison of an individual’s speech intelligibility as it relates to that of the average normal hearing individual. This comparison places the individual on a scale of speech intelligibility defined by the norms that accompany the HINT in each language.

Development of the Cantonese Hearing In Noise Test (CHINT)

Objective: To develop a Cantonese version of the Hearing In Noise Test (CHINT) with the same features as the English Hearing In Noise Test (HINT) (Nilsson, Soli, & Sullivan, 1994). Design: The CHINT was developed in five separate studies: (1) evaluation of initial materials; (2) creation of sentence materials; (3) equalization of sentence difficulty; (4) creation of sentence lists; and (5) evaluation of response variability, inter-list reliability, and establishment of norms. Using the CHINT material, reception thresholds for sentences were measured under four headphone test conditions: Quiet, and in noise with noise simulated as originating from 0° (noise front), 90° (noise right), and 270° (noise left). The speech source was located at 0° in all conditions. The locations of the speech and noise sources were simulated using virtual audio processing, as with the English HINT. The noise conditions consisted of listening with noise fixed at 65 dBA with the level of speech varied in an adaptive procedure. A total of 142 subjects with normal hearing thresholds participated in the five studies. Results: Two versions of the test materials, twenty-four 10-sentence lists and twelve 20-sentence lists, were created from a single set of 240 sentences containing 10 syllables per sentence. Using the twenty-four 10-sentence lists, mean thresholds under earphones in quiet were measured at 19.4 dBA and reception thresholds for sentences of −3.9 dB for noise front, −10.6 dB for noise right, and −10.5 dB for noise left. Similar results were obtained using the 20-sentence lists (19.4, −4.0, −10.9, and −11.0 dB, respectively, for quiet, noise front, noise right, and noise left conditions). There was low response variability within each list. High inter-list reliability suggests that consistent results could be obtained using any list. Confidence intervals are reported. The CHINT norms for listening in quiet and noise conditions were comparable to those for the English HINT. Conclusions: The CHINT is the first standardized Cantonese sentence speech intelligibility test. The CHINT was developed using the same rationale as the English HINT, allowing norm reference results from the two tests to be compared directly across languages. Results showed the CHINT is a reliable test. The CHINT would benefit from further evaluation of validity.

Recognition of vowels from information in fricatives: Perceptual evidence of fricative‐vowel coarticulation

Four studies investigated the perceptual effects of spectral variations in fricatives produced in different vowel contexts. The alveolar and palatal fricatives, [s, z, integral of, 3], were produced by two talkers in the context of the vowels [a, i, u], generating 12 fricative-vowel combinations. A computer-controlled editing procedure was used to excise fricative segments of 150-ms duration, as measured back from vowel onset. These excised segments were used as test stimuli in the four experiments. In the first experiment, fricative identification was highly accurate, especially for segments produced in the [a] context. The results of the subsequent three vowel identification experiments, revealed that the high vowels [i] and [u] were identified 60%--80% of the time in all fricative contexts, with the exception of [i] produced in the context of [integral of]. In contrast, identification scores for [a] were close to chance in all fricative contexts. Acoustic analyses of the stimuli revealed that the fricative segments with high vowel identification scores exhibited clear evidence of spectral changes associated with the vowels, while those segments with the highest fricative identification scores exhibited spectra most similar to fricatives produced in isolation. These results, in combination with more extensive acoustic analyses [S. D. Soli, J. Acoust. Soc. Am. 70, 976--984 (1981)] are discussed in terms of variations in the articulatory compatibility of tongue movements required to produce fricative-vowel sequences.