Long-term Average Speech Spectrum Research Articles

Development of 20-Talker Korean Sentence In Noise Test Lists

Purpose: Clinical speech recognition measures often present the sentences recorded with a single speaker and one rate of speech. Performances with single-talker recordings may not accurately represent the speech recognition abilities of the listeners in a multitalker communication situation. The present study aimed to construct and optimize the sentences recorded by 20 different talkers for sentence-in-noise recognition tests (20-talker Korean sentence-in-noise test, 20-talker K-SIN).Methods: Phases I and II were conducted in this study. In phase I (developmental phase), preliminary 720 sentences composed of 3 to 6 words were selected and recorded by twenty different talkers (10 male and 10 female). The recorded sentences were superimposed to generate a speech-shaped noise similar to the long-term average speech spectrum of the sentences. In phase II (optimization and formation of equally intelligible sentence lists), the psychometric functions of 30 normal-hearing listeners were obtained from the sentence-in-noise recognition scores at three different signal-to-noise ratios (SNRs) (-2, -4, and -7 dB). Based on these scores, the SNR required for 50% sentence intelligibility (SNR-50) and the slope at that point were derived from the psychometric function curves.Results: Before level adjustment, the median SNR-50 and slope were -4.12 dB SNR and 24.33%/dB over 720 sentences. Level adjustments were applied to homogenize the intelligibility of the sentences, resulting in 508 sentences remained. Out of 508 sentences, 320 sentences were used to construct 1 practice list and 15 test lists, wherein 20 sentences in each list were spoken by each of the 20 different talkers.Conclusion: The 20-talker K-SIN sentences can be used for high-variability speech-in-noise recognition test to better reflect the multitalker communication abilities of listeners.

Comparing LTASS across languages using natural and AI speech samples

Hearing aid prescription protocols rely on estimates of speech spectra. One such estimate, the International Long-Term Average Speech Spectrum (ILTASS), is a common reference for the distribution of spectral energy within speech signals. However, recent research has suggested differences in speech spectra between some languages and the ILTASS standard. These disparities raise questions regarding the applicability of a language-general approach to hearing aid gain application. This study presents a comparative analysis of Long-Term Average Speech Spectra (LTASS) across various languages. Utilizing speech samples from both human and AI sources, LTASS was measured for speakers of different languages. Subsequently, these LTASS profiles were contrasted with the established ILTASS reference. Results reveal that while LTASS was very similar across languages, deviations were observed between LTASS derived from the human speech and AI speech data compared to ILTASS. Specifically, measured LTASS demonstrated a reduced 500 Hz peak in contrast to ILTASS. This research underscores the importance of accounting for spectral variations introduced during the recording process in the field of speech and hearing research. It also emphasizes the importance of standardized recording protocols to enhance the precision of hearing technologies.

Development of the Polish Speech Test Signal and its Comparison with the International Speech Test Signal

The aim of this study was to create a single-language counterpart of the International Speech Test Signal (ISTS) and to compare both with respect to their acoustical characteristics. The development procedure of the Polish Speech Test Signal (PSTS) was analogous to the one of ISTS. The main difference was that instead of multi-lingual recordings, speech recordings of five Polish speakers were used. The recordings were cut into 100–600 ms long segments and composed into one-minute long signal, obeying a set of composition rules, imposed mainly to preserve a natural, speech-like features of the signal. Analyses revealed some differences between ISTS and PSTS. The latter has about twice as high volume of voiceless fragments of speech. PSTS’s sound pressure levels in 1/3-octave bands resemble the shape of the Polish long-term average female speech spectrum, having distinctive maxima at 3–4 and 8–10 kHz which ISTS lacks. As PSTS is representative of Polish language and contains inputs from multiple speakers, it can potentially find an application as a standardized signal used during the procedure of fitting hearing aids for patients that use Polish as their main language.

Speech directivity patterns generated from a high-fidelity speech corpus

Human talkers are directional sound sources—a phenomenon that has consequences for speech perception in multi-talker environments. Directivity patterns for speech showing frequency- and angle-dependent radiation reveal that speech generally becomes more directional toward the front of the talker as frequency increases. Differences in physical attributes can lead to individual variability in directivity patterns across talkers. Here, we examine individual variability in speech directivity using frequency-dependentdirectivity indices and directivity maps. Speech directivity was examined in the horizontal plane using a corpus of simultaneous multi-channelfull-bandwidth (48-kHz sampling rate) recordings of the Bamford-Kowal-Bench (BKB) sentences recorded in an anechoic chamber. Thirty subjects (15 female) were recorded. The long-term average speech spectrum was utilized to calculate directivity indices in 1-ERB (equivalent rectangular bandwidth) bands. Gender differences in directivity indices were evaluated using a linear mixed-effects model. There was no main effect of gender. There was a main effect of ERB band with higher-frequency bands tending to have higher (i.e., more directional) directivity indices, however there was a nonmonotonic relationship between average directivity indices and frequency. Directivity maps demonstrated individual differences in speech radiation. [Work supported by NIH under Grant No. R01-DC019745.]

Gender, but not speech material, affects extended high-frequencylevels in the speech spectrum

Current evidence suggests extended high-frequency (EHF) speech cues support speech perception. Audibility of these cues likely depends on speech spectral levels at EHFs. These levels may vary across genders and different speech materials. In this study, we investigated the effect of talker gender and speech materials on EHF levels in speech. A group of 30 (15female) native speakers of American-English was recruited to participate in this study. A three-minute spontaneous narrative was recorded for each participant along with a subset of the Bamford-Kowal-Bench (BKB) sentences. An ERB-scaled long-term average speech spectrum was calculated for the narrative and for the BKB sentences for each subject. Linear mixed-effects models were used to test intersubject and intrasubject variability in 8 EHF ERB bands. There was a significant effect of gender with female EHF levels ∼4 dB higher than male EHF levels. Within-subjects comparison of BKB sentences and narratives revealed no significant difference in EHF levels between speech materials. These findings highlight the possibility that EHFs could play a more prominent role in female speech perception than male speech perception, and suggest that EHF levels are relatively stable across speech materials for a given talker. [Work supported by NIH under Grant No. R01-DC019745.]

An objective comparison of speech intelligibility and quality of hearing aid of different companies

Abstract Purpose: This study aimed to verify the intelligibility and quality of hearing aid-processed speech across companies through objective measures. The output of hearing aids programmed to different prescriptive formulae (Company fit, NAL NL 1, NAL NL 2, and DSLv5) across companies (Company I, Company II, Company III, Company IV, and Company V) were recorded and stored in the sound level meter connected to the manikin. Materials and Methods: Offline analysis of speech quality of the recorded speech was done using the Hearing Aid Speech Quality Index (HASQI), the intelligibilty was measured using the Hearing Aid Speech Perception Index (HASPI) and Speech Intelligibility Index (SII), and Long-Term Average Speech Spectrum (LTASS) was used to measure the spectral composition of speech. Results: When the companies are compared, the hearing aid of Company V showed significantly higher SII values for all prescriptive formulae indicative of better speech intelligibility provided by Company V hearing aids. In terms of speech quality, all the hearing aids showed similar HASQI values. Conclusions: The reasons for each of these findings are highlighted and recommendations for best practices on the use of objective measures for verifying the hearing aid output in clinical setups are suggested.

과학영재학교 재학생 영어발화 주파수 대역별 음향 에너지 분포의 영어 성취도 예측성 연구*

The average acoustic distribution of American English speakers was statistically compared with the English-speaking patterns of gifted students in a Science Academy in Korea. By analyzing speech recordings, the duration time of which is much longer than in previous studies, this research identified the degree of acoustic proximity between the two parties and the predictability of English academic achievement of gifted high school students. Long-term spectral acoustic power distribution vectors were obtained for 2,048 center frequencies in the range of 20 Hz to 20,000 Hz by applying an long-term average speech spectrum (LTASS) MATLAB code. Three more variables were statistically compared to discover additional indices that can predict future English academic achievement: the receptive vocabulary size test, the cumulative vocabulary scores of English formative assessment, and the English Speaking Proficiency Test scores. Linear regression and correlational analyses between the four variables showed that the receptive vocabulary size test and the low-frequency vocabulary formative assessments which require both lexical and domain-specific science background knowledge are relatively more significant variables than a basic suprasegmental level English fluency in the predictability of gifted students’ academic achievement.

Long-Term Average Speech Spectra and Dynamic Ranges of 17 Indian Languages.

In this work, we have determined the long-term average speech spectra (LTASS) and dynamic ranges (DR) of 17 Indian languages. This work is important because LTASS and DR are language-dependent functions used to fit hearing aids, calculate the Speech Intelligibility Index, and recognize speech automatically. Currently, LTASS and DR functions for English are used to fit hearing aids in India. Our work may help improve the performance of hearing aids in the Indian context. Speech samples from native talkers were used as stimuli in this study. Each speech sample was initially cleaned for extraneous sounds and excessively long pauses. Next, LTASS and DR functions for each language were calculated for different frequency bands. Similar analysis was also performed for English for reference purposes. Two-way analysis of variance was also conducted to understand the effects of important parameters on LTASS and DR. Finally, a one-sample t test was conducted to assess the significance of important statistical attributes of our data. We showed that LTASS and DR for Indian languages are 5-10 dB and 11 dB less than those for English. These differences may be due to lesser use rate of high-frequency dominant phonemes and preponderance of vowel-ending words in Indian languages. We also showed that LTASS and DR do not differ significantly across Indian languages. Hence, we propose a common LTASS and DR for Indian languages. We showed that differences in LTASS and DR for Indian languages vis-à-vis English are large and significant. Such differences may be attributed to phonetic and linguistic characteristics of Indian languages.

Cross-language comparison of long-term average speech spectrum and dynamic range for three Indian languages and British English

Purpose: The Long-Term Average Speech Spectrum (LTASS) and Dynamic Range (DR) of speech strongly influence estimates of Speech Intelligibility Index (SII), gain and compression required for hearing aid fitting. It is also known that acoustic and linguistic characteristics of a language have a bearing on its LTASS and DR. Thus, there is a need to estimate LTASS and DR for Indian languages. The present work on three Indian languages fills this gap and contrasts LTASS and DR attributes of these languages against British English.Methods: For this purpose, LTASS and DR were measured for 21 one-third octave bands in the frequency range of 0.1 to 10 kHz for Hindi, Kannada, Indian English and British English.Results: Our work shows that the DR of Indian languages studied is 7-10 dB less relative to that of British English. We also report that LTASS levels for Indian languages are 7 dB lower relative to British English for frequencies above 1 kHz. Finally, we observed that LTASS and DR attributes across genders were more or less the same.Conclusions: Given the evidence presented in this work that LTASS and DR characteristics for Indian languages analyzed are markedly different than those for BE, there is a need to determine Indian language specific SII, as well as gain and compression parameters used in hearing aids.

Amplification rationale for hearing aids based on characteristics of the Japanese language

ObjectiveHearing aid amplification rationales have typically been developed by using global averages of the long-term average speech spectrum (LTASS) from Western European languages. However, there are few reports on hearing-aid amplification based on acoustic-phonetic characteristics of the Japanese language. This study’s objective is to investigate the LTASS for Japanese, and to compare a typical amplification rationale originally developed mainly for Western European languages with an amplification rationale specifically adjusted to the LTASS for Japanese. MethodsLTASS for two speech materials provided by four Japanese talkers were analyzed using 1/3 octave bandwidth filters. The speech was recorded with different levels of vocal effort, yielding three LTASS for “soft”, “moderate” and “loud” speech. From these results, a gain offset of the hearing-aid amplification for Japanese was obtained as compared to ANSI S3.5. Speech intelligibility for an amplification rationale for Western European languages and the newly-developed Japanese version was obtained for presentation levels of 50 dB SPL, 65 dB SPL and 80 dB SPL. Nineteen people with mild to moderate hearing loss participated in the speech intelligibility experiment. Scores in% correct were arcsine-transformed and subjected to repeated measures ANOVA with pairwise comparisons of significant main effects using Bonferroni adjustments for multiple comparisons. ResultsThe LTASS for Japanese was slightly different from the values of previous reports. A comparison of LTASS values to ANSI S3.5 with values for Japanese showed that the Japanese amplification rationale for “moderate” speech levels required more gain in the low-frequency area, and less gain in the high-frequency area. There was no significant difference in the speech intelligibility level between the amplification characteristics of Western European languages and Japanese language at each presentation level. ConclusionIt was shown that for hearing-aid amplification for Japanese, adjustments based on LTASS differences for Western European Languages could be made. This preserved speech intelligibility at the same level as the original amplification rationale, suggesting that there was no need to consider differences in phonetics of Japanese to optimize speech understanding.

A Study on the Korean Conversation Speech Level and Spectrum in Sound-Treated Environment

Purpose: Several studies have reported the differences between Korean and other countries’ speech in long-term average speech spectrum (LTASS) and band importance function. Authors tried to identify the conversational speech level, the resulting spectrum, and the LTASS for Korean. The purpose of this study was to support the production of a Korean-type hearing aid fitting formula to effectively improve the sound quality of hearing aids and the communication abilities with hearing aids, and to standardize the sound stimuli required to measure the performance of hearing aids. Methods: A total of 73 participants with normal hearing and with no specific voice and language deficits was voluntarily recruited from capital, Gyeongsang and Jeolla areas. The conversational speech level was measured by vocalizing ‘soft,’ ‘moderate,’ ‘raised,’ and ‘loud’ at a distance of 1.0 m from the speaker. And LTASS was measured by vocalizing it at a distance of 0.2 m from the speaker. Results: There was a difference in the mean of males and females in the conversation level, but no significant regional differences were shown. The conversational speech level corresponding to 30th, 65th, and 99th percentiles was 59.67, 64.74, and 79.07 dB sound pressure level, respectively. And the speech spectrum of 30th, 65th, and 99th percentile and LTASS showed in different forms from the international speech test signal. Conclusion: The results of this study should help to calculate the Korean type hearing aid fitting formula and should be used as the basic data to determine the characteristics of the sound stimuli when measuring the performance of the hearing aid.

Comparison of Speech Rate and Long-Term Average Speech Spectrum between Korean Clear Speech and Conversational Speech.

Background and ObjectivesClear speech is an effective communication strategy used in difficult listening situations that draws on techniques such as accurate articulation, a slow speech rate, and the inclusion of pauses. Although too slow speech and improperly amplified spectral information can deteriorate overall speech intelligibility, certain amplitude of increments of the mid-frequency bands (1 to 3 dB) and around 50% slower speech rates of clear speech, when compared to those in conversational speech, were reported as factors that can improve speech intelligibility positively. The purpose of this study was to identify whether amplitude increments of mid-frequency areas and slower speech rates were evident in Korean clear speech as they were in English clear speech.Subjects and MethodsTo compare the acoustic characteristics of the two methods of speech production, the voices of 60 participants were recorded during conversational speech and then again during clear speech using a standardized sentence material.ResultsThe speech rate and longterm average speech spectrum (LTASS) were analyzed and compared. Speech rates for clear speech were slower than those for conversational speech. Increased amplitudes in the mid-frequency bands were evident for the LTASS of clear speech.ConclusionsThe observed differences in the acoustic characteristics between the two types of speech production suggest that Korean clear speech can be an effective communication strategy to improve speech intelligibility.

Contribution of frequency bands to the loudness of broadband sounds: Tonal and noise stimuli.

Contributions of individual frequency bands to judgments of total loudness can be assessed by varying the level of each band independently from one presentation to the next and determining the relation between the change in level of each band and the loudness judgment. In a previous study, measures of perceptual weight obtained in this way for noise stimuli consisting of 15 bands showed greater weight associated with the highest and lowest bands than loudness models would predict. This was true even for noise with the long-term average speech spectrum, where the highest band contained little energy. One explanation is that listeners were basing decisions on some attribute other than loudness. The current study replicated earlier results for noise stimuli and included conditions using 15 tones located at the center frequencies of the noise bands. Although the two types of stimuli sound very different, the patterns of perceptual weight were nearly identical, suggesting that both sets of results are based on loudness judgments and that the edge bands play an important role in those judgments. The importance of the highest band was confirmed in a loudness-matching task involving all combinations of noise and tonal stimuli.

Ins, Outs of Frequency-lowering Processing

Ins, Outs of Frequency-lowering Processing

Long-term Average Speech Spectra of Postlingual Cochlear Implant Users

Long term average speech spectra (LTASS) is a commonly used voice analysis method for different purposes. This method offers an acoustic representation of the language in daily conservations. Results of that method can be altered by the deteriorations in the auditory feedback loop. Hearing losses occurred in the post lingual stage of life have some serious negative effects on the auditory feedback loop. Cochlear implantation may help these patients with regards to auditory feedback loop. Therefore, we aimed to evaluate the LTASS of cochlear implant users whose have a post lingual hearing loss. We assessed the LTASS of 24 cochlear implant users and compared our findings with normal hearing subjects. Our findings revealed that cochlear implant users have similar LTASS findings with normal hearing subjects. We conclude that cochlear implantation helps to the recovery of auditory feedback loop in patients with post lingual hearing losses.

A revised speech spectrum for STI calculations

The ability of the Speech Transmission Index (STI) to predict speech intelligibility under noisy conditions is highly dependent on the assumed spectrum of the speech signal. Examination of the literature showed that the long-term average speech spectrum of male talkers differs substantially from the speech spectrum recommended for STI calculations (IEC 60268-16). To explore these issues, the long-term average speech spectrum of forty male British English people was first measured, compared with the available literature and proposed for STI calculations. Then, using several voice alarm systems, the influence of the measured spectrum on STI calculations was assessed and comparisons made with the standard speech spectrum. The results showed significant STI differences under noisy conditions and considerable reductions in the required electrical power with the use of the new proposed male spectrum. This indicated that the current STI method could benefit from a revised speech spectrum.

Long term average speech spectra of Turkish

Long-term average speech spectra (LTASS) are a voice analysis method that is recommended to be used in various areas, such as hearing aid fittings, automatic speaker recognition and voice disorders. Evaluations of LTASS in different languages have been published; however, this analysis has not been conducted for the Turkish. Therefore, the first aim of this study was to conduct this analysis, generate normative values and compare the obtained LTASS curve for the Turkish with those obtained for other languages reported in the literature. To achieve this objective, 40 adults with healthy hearing and speech characteristics were evaluated. Long-term spectral shape is presented in a graphical form, with visual comparisons to other research findings. Spectral differences by gender were analyzed, with statistically significant differences observed between gender groups and overall LTASS. The LTASS curve for the Turkish is similar to those reported for other languages, but there are also observable differences. Use of generated speech signals in hearing aid fitting procedures is recommended.

Relative contributions of specific frequency bands to the loudness of broadband sounds.

Listeners with normal hearing (NH) and sensorineural hearing loss (SNHL) were asked to compare pairs of noise stimuli and choose the louder noise in each pair. Each noise was made up of 15, two-ERBN (equivalent rectangular bandwidth) wide frequency bands that varied independently over a 12-dB range from one presentation to the next. Mean levels of the bands followed the long-term average speech spectrum (LTASS) or were set to 43, 51, or 59 dB sound pressure level (SPL). The relative contribution of each band to the total loudness of the noise was determined by computing the correlation between the difference in levels for a given band on every trial and the listener's decision on that trial. Weights for SNHL listeners were governed by audibility and the spectrum of the noise stimuli, with bands near the spectral peak of the LTASS noise receiving greatest weight. NH listeners assigned greater weight to the lowest and highest bands, an effect that increased with overall level, but did not assign greater weight to bands near the LTASS peak. Additional loudness-matching and paired-comparison studies using stimuli missing one of the 15 bands showed a significant contribution by the highest band, but properties other than loudness may have contributed to the decisions.

Akustičke značajke vokalnoga zamora

Vocal fatigue is characterized by self-perceived increased laryngeal strain and voice quality changes. The condition can have organic or/and functional causes. Typically, it affects vocal professionals, and teachers are most numerous among them. Despite great number of studies, many questions about vocal fatigue such as its acoustic characterstics are still open. The hypothesis of the present study conducted on female teachers was that there are significant differences in acoustic variables between vocally fatigued teachers (N=23) and teachers without it (N=27). Running speech and prolonged phonation of the vowel /a/ were analyzed in PRAAT software calculating the long-term average speech spectrum LTASS and harmonic spectrum. The average speech F0 and series of spectral variables were calculated: the strength of the strongest spectral peak L0, the α ratio of the level difference above and bellow 1 kHz for the 0-5 kHz range analyzed, and the variables Δ1, Δ2, Δ3 and Δ4 showing the ratios of the respective spectral energy bands of 1-2 kHz, 2-3 kHz, 3-4 kHz and 4-5 kHz relative to the 0-1 kHz reference. The average H1/H2 ratio based on harmonic spectrum of three samples of the prolonged vowel /a/ production was calculated as well. The hypothesis was tested by multivariate and univariate analyzes of variance and discriminant analysis. The results showed that there are no significant differences in the set of acoustic variables between the two teacher groups, thus the hypothesis was rejected. However, the average speech F0 showed to be strong single discriminator. Its mean value in the group of teachers with vocal fatigue, that is 176 Hz, suggests dysfunction. Several factors may explain the absence of acoustic differences between the two groups, one of the most compelling of which is the fact that both groups reported similar numbers of subjective vocal and physical complaints. The results confirm the complex phenomenology of vocal fatigue syndrome, and suggest that acoustic analysis may have limited power to detect it.

The Impact of Language on Voice: An LTAS Study

The present study investigates possible differences in sound characteristics associated with Farsi and Qashqai produced by Farsi-Qashqai bilinguals. This is a descriptive-analytical and cross-sectional study. Thirty-two Farsi-Qashqai bilinguals (16 men and 16 women) participated in the study. Mean spectral energy (MSE) and spectral tilt (ST) obtained from long-term average speech spectra were extracted from continuous speech samples of Farsi-Qashqai bilingual speakers. MSE and ST were calculated using Praat and then compared between Farsi and Turkish. Results showed that bilingual speakers had higher MSE and lower ST in Farsi than in Turkish. Findings show that even with the same phonatory apparatus, spoken language affects the speaker's voice quality.