1aAA4 – Optimizing the signal to noise ratio in classrooms using passive acoustics

Peter D’Antonio – pdantonio@rpginc.com

RPG Diffusor Systems, Inc.
651 Commerce Dr
Upper Marlboro, MD 20774

Popular version of paper 1aAA4 “Optimizing the signal to noise ratio in classrooms using passive acoustics”
Presented on Monday May 23, 10:20 AM – 5:00 pm, SALON I
171st ASA Meeting, Salt Lake City

The 2012 Program of International Student Assessment (PISA) has carried out an international comparative trial of student performance in reading comprehension, calculus, and natural science. The US ranks 36th out of 64 countries testing ½ million 15 year olds, as shown in Figure 1.

Dantonio1

Figure 1 PISA Study

What is the problem? Existing acoustical designs and products have not evolved to incorporate the current state-of-the-art and the result is schools that are failing to meet their intended goals. Learning areas are only beginning to include adjustable intensity and color lighting, shown to increase reading speeds, reduce testing errors and reduce hyperactivity; existing acoustical designs are limited to conventional absorptive-only acoustical materials, like thin fabric wrapped panels and acoustical ceiling tiles, which cannot address all of the speech intelligibility and music appreciation challenges.

What is the solution? Adopt modern products and designs for core and ancillary learning spaces which utilize binary, ternary, quaternary and other transitional hybrid surfaces, which simultaneously scatter consonant-containing high frequency early reflections and absorb mid-low frequencies to passively improve the signal to noise ratio, adopt recommendations of ANSI 12.6 to control reverberation, background noise and noise intrusion and integrate lighting that adjusts to the task at hand.

Let’s begin by considering how we hear and understand what is being said when information is being delivered via the spoken word. We often hear people say, I can hear what he or she is saying, but I cannot understand what is being said. The understanding of speech is referred to as speech intelligibility. How do we interpret speech? The ear / brain processor can fill in a substantial amount of missing information in music, but requires more detailed information for understanding speech. The speech power is delivered in the vowels (a, e, i, o, u and sometimes y) which are predominantly in the frequency range of 250Hz to 500Hz. The speech intelligibility is delivered in the consonants (b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w), which occur in the 2,000Hz to 6,000 Hz frequency range. People who suffer from noise induced hearing loss typically have a 4,000Hz notch, which causes severe degradation of speech intelligibility. I raise the question, “Why would we want to use exclusively absorption on the entire ceiling of a speech room and thin fabric wrapped panels on a significant proportion of wall areas, when these porous materials absorb these important consonant frequencies and prevents them from fusing with the direct sound making it louder and more intelligible?

Exclusive treatment of absorbing material on the ceiling of the room may excessively reduce the high-frequency consonants sound and result in the masking of high-frequency consonants by low-frequency vowel sounds, thereby reducing the signal to noise ratio (SNR).

The signal has two contributions. The direct line-of-sight sound and the early reflections arriving from the walls, ceiling, floor and people and items in the room. So the signal consists of direct sound and early reflection. Our auditory system, our ears and brain, have a unique ability called temporal fusion, which combines or fuses these two signals into one apparently louder and more intelligible signal. The goal then is to utilize these passive early reflections as efficiently as possible to increase the signal. The denominator in the SNR consists of external noise intrusion, occupant noise, HVAC noise and reverberation. These ideas are summarized in Figure 2.

Dantonio figure2

Figure 2 Signal to Noise Ratio

In Figure 3, we illustrate a concept model for an improved speech environment, whether it is a classroom, a lecture hall, a meeting/conference room, essentially any room in which information is being conveyed.

The design includes a reflective front, because the vertical and horizontal divergence of the consonants is roughly 120 degrees, so if a speaker turns away from the audience, the consonants must reflect from the front wall and ceiling overhead. The perimeter of the ceiling is absorptive to control the reverberation (noise). The center of the ceiling is diffusive to provide early reflections to increase the signal and its coverage in the room. The mid third of the walls utilize novel binary, ternary, quaternary and other transitional diffsorptive (diffusive/absorptive) panels, which scatter the information above 1 kHz (the signal) and absorb the sound below 1 kHz (the reverberation=noise). This design suggests that the current exclusive use of acoustical ceiling tile and traditional fabric wrapped panels is counterproductive in improving the SNR, speech intelligibility and coverage.

Dantonio figure3 - classrooms

Figure 3 Concept model for a classroom with a high SNR

2aSP5 – Using Automatic Speech Recognition to Identify Dementia in Early Stages

Roozbeh Sadeghian, J. David Schaffer, and Stephen A. Zahorian
Rsadegh1@binghamton.edu
SUNY at Binghamton
Binghamton, NY

Popular version of paper 2aSP5, “Using automatic speech recognition to identify dementia in early stages”
Presented Tuesday morning, November 3, 2015, 10:15 AM, City Terrace room
170th ASA Meeting, Jacksonville, Fl

The clinical diagnosis of Alzheimer’s disease (AD) and other dementias is very challenging, especially in the early stages. It is widely believed to be underdiagnosed, at least partially because of the lack of a reliable non-invasive diagnostic test.  Additionally, recruitment for clinical trials of experimental dementia therapies might be improved with a highly specific test. Although there is much active research into new biomarkers for AD, most of these methods are expensive and or invasive such as brain imaging, often with radioactive tracers, or taking blood or spinal fluid samples and expensive lab procedures.

There are good indications that dementias can be characterized by several aphasias (defects in the use of speech). This seems plausible since speech production involves many brain regions, and thus a disease that effects particular regions involved in speech processing might leave detectable finger prints in the speech. Computerized analysis of speech signals and computational linguistics (analysis of word patterns) have progressed to the point where an automatic speech analysis system could be within reach as a tool for detection of dementia. The long-term goal is an inexpensive, short duration, non-invasive test for dementia; one that can be administered in an office or home by clinicians with minimal training.

If a pilot study (cross sectional design: only one sample from each subject) indicates that suitable combinations of features derived from a voice sample can strongly indicate disease, then the research will move to a longitudinal design (many samples collected over time) where sizable cohorts will be followed so that early indicators might be discovered.

A simple procedure for acquiring speech samples is to ask subjects to describe a picture (see Figure 1). Some such samples are available on the web (DementiaBank), but they were collected long ago and the audio quality is often lacking in quality. We used 140 of these older samples, but also collected 71 new samples with good quality audio. Roughly half of the samples had a clinical diagnosis of probable AD, and the others were demographically similar and cognitively normal (NL).

(a) (b)Sadeghian Figure1b

Figure 1- The picture used for recording samples (a) famous cookie theft samples and (b) newly recorded samples

One hundred twenty eight features were automatically extracted from speech signals, including pauses and pitch variation (indicating emotion); word-use features were extracted from manually-prepared transcripts. In addition, we had the results of a popular cognitive test, the mini mental state exam (MMSE) for all subjects. While widely used as an indicator of cognitive difficulties, the MMSE is not sufficiently diagnostic for dementia by itself. We searched for patterns with and without the MMSE. This gives the possibility of a clinical test that combines speech with the MMSE. Multiple patterns were found using an advanced pattern discovery approach (genetic algorithms with support vector machines). The performances of two example patterns are shown in Figure 2. The training samples (red circles) were used to discover the patterns, so we expect them to perform well. The validation samples (blue) were not used for learning, only to test the discovered patterns. If we say that a subject will be declared AD if the test score is > 0.5 (the red line in Figure 2), we can see some errors: in the left panel we see one false positive (NL case with a high test score, blue triangle) and several false negatives (AD cases with low scores, red circles).  

Sadeghian 2_graphs - Dementia

Figure 2. Two discovered diagnostic patterns (left with MMSE) (right without MMSE). The normal subjects are to the left in each plot (low scores) and the AD subjects to the right (high scores). No perfect pattern has yet been discovered. 

As mentioned above, manually prepared transcripts were used for these results, since automatic speaker-independent speech recognition is very challenging for small highly variable data sets.  To be viable, the test should be completely automatic.  Accordingly, the main emphasis of the research presented at this conference is the design of an automatic speech-to-text system and automatic pause recognizer, taking into account the special features of the type of speech used for this test of dementia.

2pSCb11 – Effect of Menstrual Cycle Hormone Variations on Dichotic Listening Results

Richard Morris – Richard.morris@cci.fsu.edu
Alissa Smith

Florida State University
Tallahassee, Florida

Popular version of poster presentation 2pSCb11, “Effect of menstrual phase on dichotic listening”
Presented Tuesday afternoon, November 3, 2015, 3:30 PM, Grand Ballroom 8

How speech is processed by the brain has long been of interest to researchers and clinicians. One method to evaluate how the two sides of the brain work when hearing speech is called a dichotic listening task. In a dichotic listening task two words are presented simultaneously to a participant’s left and right ears via headphones. One word is presented to the left ear and a different one to the right ear. These words are spoken at the same pitch and loudness levels. The listener then indicates what word was heard. If the listener regularly reports hearing the words presented to one ear, then there is an ear advantage. Since most language processing occurs in the left hemisphere of the brain, most listeners attend more closely to the right ear. The regular selection of the word presented to the right ear is termed a right ear advantage (REA).

Previous researchers reported different responses from males and females to dichotic presentation of words. Those investigators found that males more consistently heard the word presented to the right ear and demonstrated a stronger REA. The female listeners in those studies exhibited more variability as to the ear of the word that was heard. Further research seemed to indicate that women exhibit different lateralization of speech processing at different phases of their menstrual cycle. In addition, data from recent studies indicate that the degree to which women can focus on the input to one ear or the other varies with their menstrual cycle.

However, the previous studies used a small number of participants. The purpose of the present study was to complete a dichotic listening study with a larger sample of female participants. In addition, the previous studies focused on women who did not take oral contraceptives as they were assumed to have smaller shifts in the lateralization of speech processing. Although this hypothesis is reasonable, it needs to be tested. For this study, it was hypothesized that the women would exhibit a greater REA during the days that they menstruate than during other days of their menstrual cycle. This hypothesis was based on the previous research reports. In addition, it was hypothesized that the women taking oral contraceptives will exhibit smaller fluctuations in the lateralization of their speech processing.

Participants in the study were 64 females, 19-25 years of age. Among the women 41 were taking oral contraceptives (OC) and 23 were not. The participants listened to the sound files during nine sessions that occurred once per week. All of the women were in good general health and had no speech, language, or hearing deficits.

The dichotic listening task was executed using the Alvin software package for speech perception research. The sound file consisted of consonant-vowel syllables comprised of the six plosive consonants /b/, /d/, /g/, /p/, /t/, and /k/ paired with the vowel “ah”. The listeners heard the syllables over stereo headphones. Each listener set the loudness of the syllables to a comfortable level.

At the beginning of the listening session, each participant wrote down the date of the initiation of her most recent menstrual period on a participant sheet identified by her participant number. Then, they heard the recorded syllables and indicated the consonant heard by striking that key on the computer keyboard. Each listening session consisted of three presentations of the syllables. There were different randomizations of the syllables for each presentation. In the first presentation, the stimuli will be presented in a non-forced condition. In this condition the listener indicted the plosive that she heard most clearly. After the first presentation, the experimental files were presented in a manner referred to as a forced left or right condition. In these two conditions the participant was directed to focus on the signal in the left or right ear. The sequence of focus on signal to the left ear or to the right ear was counterbalanced over the sessions.

The statistical analyses of the listeners’ responses revealed that no significant differences occurred between the women using oral contraceptives and those who did not. In addition, correlations between the day of the women’s menstrual cycle and their responses were consistently low. However, some patterns did emerge for the women’s responses across the experimental sessions as opposed to the days of their menstrual cycle. The participants in both groups exhibited a higher REA and lower percentage of errors for the final sessions in comparison to earlier sessions.

The results from the current subjects differ from those previously reported. Possibly the larger sample size of the current study, the additional month of data collection, or the data recording method affected the results. The larger sample size might have better represented how most women respond to dichotic listening tasks. The additional month of data collection may have allowed the women to learn how to respond to the task and then respond in a more consistent manner. The short data collection period may have confused the learning to respond to a novel task with a hormonally dependent response. Finally, previous studies had the experimenter record the subjects’ responses. That method of data recording may have added bias to the data collection. Further studies with large data sets and multiple months of data collection are needed to determine any sex and oral contraceptive use effects on REA.

4aSC2 – Effects of language and music experience on speech perception

T. Christina Zhao — zhaotc@uw.edu
Patricia K. Kuhl — pkkuhl@uw.edu
Institute for Learning & Brain Sciences
University of Washington, BOX 357988
Seattle, WA, 98195

Popular version of paper 4aSC2, “Top-down linguistic categories dominate over bottom-up acoustics in lexical tone processing”
Presented Thursday morning, May 21st, 2015, 8:00 AM, Ballroom 2
169th ASA Meeting, Pittsburgh

Speech perception involves constant interplay between top-down and bottom-up processing. For example, to process phonemes (e.g. ‘b’ from ‘p’), the listener must accurately process the acoustical information in the speech signals (i.e. bottom-up strategy) and assign these sounds efficiently to a category (i.e. top-down strategy). Listeners’ performance in speech perception tasks is influenced by their experience in either processing strategy. Here, we use lexical tone processing as a window to examine how extensive experience in both strategies influence speech perception.

Lexical tones are contrastive pitch contour patterns at the word level. That is, a small difference in the pitch contour can result in different word meaning. Native speakers of a tonal language thus have extensive experience in using the top-down strategy to assign highly variable pitch contours into lexical tone categories. This top-down influence is reflected by the reduced sensitivity to acoustic differences within a phonemic category compared to across categories (Halle, Chang, & Best, 2004). On the other hand, individuals with extensive music training early in life exhibit enhanced sensitivities to pitch differences not only in music, but also in speech, reflecting stronger bottom-up influence. Such bottom-up influence is reflected by the enhanced sensitivity in detecting differences between lexical tones when the listeners are non-tonal language speakers (Wong, Skoe, Russo, Dees, & Kraus, 2007).
How does extensive experience in both strategies influence lexical tone processing? To address this question, native Mandarin speakers with extensive music training (N=17) completed a music pitch discrimination task and a lexical tone discrimination task. We compared their performance with individuals with extensive experience in only one of the processing strategies (i.e. Mandarin nonmusicians (N=20) and English musicians (N=20), data from Zhao & Kuhl (2015)).

Despite the enhanced performance in the music pitch discrimination task in Mandarin musicians, their performance in the lexical tone discrimination task is similar to the performance of the Mandarin nonmusicians, and different from the English musicians’ performance (Fig. 1, ‘Sensitivity across lexical tone continuum by group’).
ZhaoFig1
That is, they exhibited reduced sensitivities within phonemic categories (i.e. on either end of the line) compared to within categories (i.e. the middle of the line), and their overall performance is lower than the English musicians. This result strongly suggests a dominant effect of the top-down influence in processing lexical tone. Yet, further analyses revealed that Mandarin musicians and Mandarin nonmusicians may still be relying on different underlying mechanisms for performing in the lexical tone discrimination task. In the Mandarin musician, their music pitch discrimination scores are correlated with their lexical tone discrimination scores, suggesting a contribution of the bottom-up strategy in their lexical tone discrimination performance (Fig. 2, ‘Music pitch and lexical tone discrimination’, purple). This relation is similar to the English musicians (Fig. 2, peach) but very different from the Mandarin non-musicians (Fig. 2, yellow). Specifically, for Mandarin nonmusicians, the music pitch discrimination scores do not correlate with the lexical tone discrimination scores, suggesting independent processes.

ZhaoFig2

Halle, P. A., Chang, Y. C., & Best, C. T. (2004). Identification and discrimination of Mandarin Chinese tones by Mandarin Chinese vs. French listeners. Journal of Phonetics, 32(3), 395-421. doi: 10.1016/s0095-4470(03)00016-0
Wong, P. C. M., Skoe, E., Russo, N. M., Dees, T., & Kraus, N. (2007). Musical experience shapes human brainstem encoding of linguistic pitch patterns. Nat. Neurosci., 10(4), 420-422. doi: 10.1038/nn1872
Zhao, T. C., & Kuhl, P. K. (2015). Effect of musical experience on learning lexical tone categories. The Journal of the Acoustical Society of America, 137(3), 1452-1463. doi: doi:http://dx.doi.org/10.1121/1.4913457

2aSC – Speech: An eye and ear affair!

Pamela Trudeau-Fisette – ptrudeaufisette@gmail.com
Lucie Ménard – menard.lucie@uqam.ca
Université du Quebec à Montréal
320 Ste-Catherine E.
Montréal, H3C 3P8

Popular version of poster session 2aSC, “Auditory feedback perturbation of vowel production: A comparative study of congenitally blind speakers and sighted speakers”
Presented Tuesday morning, May 19, 2015, Ballroom 2, 8:00 AM – 12:00 noon
169th ASA Meeting, Pittsburgh
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When learning to speak, young infants and toddlers use auditory and visual cues to correctly associate speech movements to a specific speech sound. In doing so, typically developing children compare their own speech and those of their ambient language to build and improve the relationship between what they hear, see and feel, and how to produce it.

In many day-to-day situations, we exploit the multimodal nature of speech: in noisy environments, for instance like in a cocktail party, we look at our interlocutor’s face and use lip reading to recover speech sounds. When speaking clearly, we open our mouth wider to make ourself sound more intelligible. Sometimes, just seeing someone’s face is enough to communicate!

What happens in cases of congenital blindness? Despite the fact that blind speakers learn to produce intelligible speech, they do not quite speak like sighted speakers do. Since they do not perceive others’ visual cues, blind speakers do not produce visible labial movements as much as their sighted peers do.

Production of the French vowel “ou” (similar as in cool) produced by a sighted adult speaker (on the left) and a congenitally blind adult speaker (on the right). We can clearly see that the articulatory movements of the lips are more explicit for the sighted speaker.

Therefore, blind speakers put more weight on what they hear (auditory feedback) than sighted speakers, because one sensory input is lacking. How does that affect the way blind individuals speak?

To answer this question, we conducted an experiment during which we asked congenitally blind adult speakers and sighted adult speakers to produce multiple repetitions of the French vowel “eu”. While they were producing the 130 utterances, we gradually altered their auditory feedback through headphones – without them knowing it- so that they were not hearing the exact sound they were saying. Consequently, they needed to modify the way they produced the vowel in order to compensate for the acoustic manipulation, so they could hear the vowel they were asked to produce (and the one they thought they were saying all along!).

What we were interested in is whether blind speakers and sighted speakers would react differently to this auditory manipulation. The blind speakers not being able to rely on visual feedback, we hypothesized that they would grant more importance on their auditory feedback and, therefore, compensate to a greater extent for the acoustic manipulation.

To explore this matter, we observed the acoustic (produced sounds) and articulatory (lips and tongue movements) differences between the two groups at three distinct time points of the experiment phases.

As predicted, congenitally blind speakers compensated for the altered auditory feedback in a greater extent than their sighted peers. More specifically, even though both speaker groups adapted their productions, the blind group compensated more than the control group did, as if they were integrating the auditory information more strongly. Also, we found that both speaker groups used different articulatory strategies to respond to the applied manipulation: blind participants used their tongue (which is not visible when you speak) more to compensate. This latter observation is not surprising considering the fact that blind speakers do not use their lips (which is visible when you speak) as much as their sighted peers do.

Tags: speech, language, learning, vision, blindness