bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of the structural admittance matrix using external random noise sources
Authors: Williams Earl G. , Tippmann Jeffery D. , Rakotonarivo Sandrine T. , Kuperman W. A.
Published: November 2016

The structural admittance Ys also called the structural Green’s function characterizes the vibration, radiation, and scattering physics of a vibrator. When it is known, the vibration of the radiating surface, and hence the acoustic radiation from the surface, is also known for any specified surface load. We demonstrate in this talk that Ys can be constructed when the object is placed in an isotropic random noise field. This construction consists of ensemble averages of cross-correlations of the resulting total normal velocity and total pressure (incident plus scattered) measured over the complete surface of the object. However, the measurement of the surface fields could be prohibitive as the temporal frequency of interest increases. Instead of a surface measurement, one can use a dual conformal surface of microphones placed near to the object together with near-field acoustical holography (NAH) to determine the fields on the surface via the back projection capability of NAH. Although a large number of sensors may be required, the advent of inexpensive MEMS microphones combined with a 3D printing capability to construct the support structure makes this measurement very plausible. [Work supported by the Office of Naval Research.]
Electronic speckle-pattern interferometry: Techniques for non-contact vibration measurements of musical percussion instruments
Authors: Worland Randy
Published: November 2016

Electronic speckle-pattern interferometry (ESPI) provides a non-contact optical system that can be used to record images showing operating deflection shapes of structures being driven sinusoidally at resonant frequencies. In high-Q systems, these shapes can approximate the normal modes of the test object. Due to the sensitivity of the optical measurement system, non-contact excitation can be achieved acoustically using a speaker. The use of ESPI is described in relation to measurements of musical bars, plates, and membranes under various boundary conditions, though the methods described can be applied to many other types of structures. In addition, a dual-ESPI system that provides simultaneous measurements of two surfaces of an object is illustrated (e.g., two heads of a musical drum). These measurements provide information regarding the degree of coupling and the relative phase of the two vibrating surfaces. Finally, the ESPI techniques are applied to the fluid-structure interaction of an orchestral crotale (a thick metal disk) at various degrees of submersion in water.
The non-contact acoustic inspection method for concrete structures using the defect detection algorithm based on the statistic evaluation for a healthy part of concrete
Authors: Sugimoto Kazuko , Sugimoto Tsuneyoshi , Kosuge Nobuaki , Kuroda Chitose , Utagawa Noriyuki
Published: November 2016

The deterioration of concrete structure becomes a social problem in Japan. Social needs increase as for maintenance, check and renewal of concrete structures such as a tunnel or a bridge. The check of concrete structures has been performed conventionally by a hammering test. Not the inspection depended on a human experience and sense, but the inspection by a quantitative measuring system are demanded. We have developed the technique “non-contact nondestructive acoustic inspection method” to measure the internal defects near the concrete surface to a depth of about 10cm using airborne sound and the laser Doppler vibrometer at a distance 5―10 m far from measurement surface. Depending on the surface state (reflectance, dirt, etc.) of concretes, there is a problem to decrease the quantity of the light of the returning laser and there arise optical noise resulting from the leakage of light reception. To remove an abnormal measurement point, we proposed a defect detection algorithm, in which vibrational energy ratio and spectrum entropy are combined. As a result, it enables to distinguish a defect part, healthy part and an abnormal measurement point. However, for a real concrete structure, the gray area exists. We evaluate quantity of acoustic characteristics against a healthy part of concrete statistically. We found the distribution of each acoustic characteristic against a healthy part follow a normal distribution by excluding some outlier. A defective part is separated from a healthy part clearly and visualized vividly.
Study on the measurement speed and signal to noise ratio of multi tone burst wave for high speed non-contact acoustic inspection method
Authors: Kosuge Nobuaki , Sugimoto Tsuneyosi , Sugimoto Kazuko , Kuroda Chitose , Utagawa Noriyuki
Published: November 2016

The non-contact acoustic inspection method using an air-borne sound can detect the cavity defect and crack near the measurement surface by using flexural resonance. By this method which uses the conventional single tone burst wave, since only one frequency was used for one sound wave emission, the length of measurement time had become a problem. Therefore, the multi-tone burst wave was devised for high speed improvement. However, measurement time and signal to noise (S/N) ratio change with the parameters in which a multi-tone burst wave is contained at the time of one sound wave emission, such as the number of frequency, the arranging method, pulse length, and the average number of times. Therefore, the experiment using the concrete test object having the styrofoam which imitated the cavity defect was conducted and a multi-tone burst wave was used, it was investigated how the measurement time and the S/N ratio of this method would change. From the experimental result, it became clear that the improvement in the measurement speed of several or more times was realizable maintaining a comparable S/N ratio as compared with the conventional single tone burst wave.
Remote acoustic sensing of mechanical changes in a plate in an unknown reverberant environment
Authors: Flynn Tyler J. , Dowling David R.
Published: November 2016

An experimental method for remote acoustic sensing of changes in radiating structures in an unknown reverberant environment is presented. Acoustic radiation from a mechanical structure due to oscillatory forcing may be described by a frequency response function (FRF) dependent on the structure’s material, geometry, and boundary conditions. Mechanical changes may alter the structure’s FRF in detectible and potentially predictable ways. However, collecting suitable FRF measurements may be difficult in reverberant environments over the necessary extended measurement times due to the influence of reflected and scattered sound. Here, experimental results are presented for the remote acoustic detection of mechanical changes to a vibrating 0.3-m-square by 3-mm-thick aluminum plate in a reverberant environment. The plate has nominally clamped edges and is subject to swept-frequency base excitation. Sound from the plate with and without a mechanical change is recorded remotely with a 15 microphone linear array. These recordings are then processed using Synthetic Time Reversal to reconstruct a single radiated sound signal that is corrected for the environment’s unknown reverberation, and this corrected signal is examined to detect mechanical changes to the test plate. Results from the proposed technique are compared with equivalent results from conventional approaches. [Sponsored by NAVSEA through the NEEC.]
Semantic predictability mediates effects of phonetic reduction and social variation on word recognition
Authors: Jones Zack , Dailey Megan M. , Clopper Cynthia G.
Published: November 2016

Phonetic reduction due to lexical frequency, phonological neighborhood density, and discourse mention, as well as speaking style and social-indexical variation can constrain listeners’ ability to identify spoken single word tokens. In phrasal contexts, however, semantic predictability facilitates word recognition. The aim of the current study was to investigate how semantic predictability influences the intelligibility of words that vary in their lexical, stylistic, and socio-indexical properties. Listeners were presented with auditory English phrases extracted from read passages and were asked to identify each phrase. Phrases were mixed with speech-shaped noise and each contained a target word of interest. Linguistic and social properties of the target words were used to predict listeners’ target word recognition accuracy. These factors included semantic predictability, lexical frequency, neighborhood density, speaking style, discourse mention within the passage, talker gender, and talker dialect. The results revealed that greater semantic predictability increased word recognition accuracy, but only for the most phonetically reduced words (e.g., high-frequency words, second mentions, and words in a plain style). These results suggest that the semantic predictability benefit is enhanced primarily for words that might otherwise be difficult to recognize when removed from their semantic context.
The N1 event-related potential component as an index of speech sound encoding for multiple phonetic contrasts
Authors: Pereira Olivia , Toscano Joe
Published: November 2016

Listeners rely on many phonetic cues to perceive speech, but it is not clear how acoustic and phonological differences are encoded at early stages of perception. Previous work has begun to address this using the event-related potential (ERP) technique, demonstrating that the amplitude of the auditory N1 ERP component varies linearly with differences along VOT continua and suggesting that it can serve as an index of cue encoding. However, it is not clear how the N1 varies more generally for other phonetic distinctions. We present ERP data for a large set of naturally-produced word-initial minimal pairs spanning 18 consonants (/b,d,tʃ,f,g,dʒ,k,l,m,n,p,ɹ,s,ʃ,t,v,w,z/), as well as stimuli varying along voice onset time (voicing) and burst frequency (place of articulation) continua for all six stop consonants. The results reveal widespread differences in N1 amplitude for place of articulation and voicing. The N1 is larger for voiced consonants than voiceless consonants. Moreover, N1 amplitude as a function of place of articulation patterns differently for fricatives (larger N1 for alveolar and post-alveolar phonemes) than for stops (smaller N1 for these place of articulation categories). Overall, these results suggest that the N1 serves as a useful index of speech sound encoding across a range of phonetic contrasts.
Asymmetries in the perception of sub-categorical variation
Authors: Nielsen Kuniko , Scarborough Rebecca
Published: November 2016

Both VOT and vowel nasality show low-level variation in English that may be perceptually motivated (and which, in any case, has perceptual consequences). This study examines the perceptual salience of such variation, investigating in particular a possible perceptual asymmetry between increased vs. decreased degrees of these phonologically relevant features. On each trial of an AXB perceptual task, listeners heard three repetitions of the same word: a token with unchanged phonetic feature (X) and tokens with phonetic features that were artificially increased and decreased to the same degree (A and B). Listeners then had to determine which of the two flanking items (A or B) sounded more similar to the middle item (X). Test words included 18 monosyllabic words with initial /p/ (in simple onsets) and 19 monosyllabic words with nasal codas and were heard by 40 listeners. Based on preliminary work, participants are expected to judge decreased-feature stimuli of both types (VOT and nasality) as more similar to the natural stimuli, suggesting that increasing these phonetic features is perceptually more salient than decreasing them. These findings demonstrate asymmetrical sub-categorical sensitivity for features known to be perceived categorically (VOT), as well as for features not primary to phonological contrast (vowel nasality).
Pre-nasal short-a in Northern California: Merged in formant space with /ɛ/, but distinct in duration and degree of nasal coarticulation
Authors: Zellou Georgia , Kemp Renee
Published: November 2016

Short-a, or /æ/, production varies substantially across American English dialects and is noted to be useful in describing regional pronunciation differences. The current study examines the production and perception of /æ/ in California English, which raises in words with a final nasal coda (both velar and non-velar nasals). We explore both the acoustic characteristics of this potential merger with /ɛ/, along with lexical confusability between words with /æ/ and /ɛ/ in prenasal position. Productions of 32 native California speakers reveal that the formant space of prenasal /æ/ indeed overlaps with /ɛ/. However, these vowels have reliably different patterns of two secondary acoustic features: duration and nasal coarticulation. /æ/ is produced with both a longer duration and a greater degree of nasal coarticulation than /ɛ/. Results from a lexical identification task presenting unaltered, as well as duration-neutralized, items to 50 listeners reveal that these vowels are not confusable despite considerable formant overlap. Furthermore, modeling results indicate that greater differences in nasalization between prenasal /æ/-/ɛ/ pairs lead to more accurate identification. Overall, the results from this study indicate that these secondary features help maintain the perceptual distinctiveness of /æ/-/ɛ/ words where formant merger has taken place.
Stability of the main resonance frequency of fricatives despite changes in the first spectral moment
Authors: Shadle Christine H. , Chen Wei-rong , Whalen D. H.
Published: November 2016

Spectral moments have been taken as the primary measurements of fricatives, but resonances are evident as well. To contrast the two, the X-ray Microbeam Database (XRMB) was used to investigate acoustic and articulatory behavior in [s] for 10 /sVd/ words and 9 /sCV*/ words for 24 subjects as in a previous study [Iskarous et al., JASA 129:2, 2011]. Spectral parameters were adapted from analysis of an acoustic corpus of adolescents’ [s] production [Koenig et al., JSLHR 56, Aug. 2013]. The time series of the frequency of the main resonance (FM) and the first spectral moment (M1) were compared to the constriction location estimated from the most anterior tongue pellet T1. FM quickly settles into a constant value largely determined by the position of T1; vowel context affects FM throughout [s] for some subjects. M1 however rises and then falls during [s], matching jaw-raising behavior (as estimated by the y-component of the jaw pellet) and correlated with an estimate of high-frequency energy. The results show that some aspects of the fricative acoustics behave differently over time and by context. It remains to be seen what the perceptual consequences of these differences are. [Work supported by NIH NIDCD-DC-002717.]
Temporal structure of repetition disfluencies in American English
Authors: Harmon Zara , Kapatsinski Vsevolod
Published: November 2016

A repetition disfluency involves an interruption in the flow of speech followed by a restart, leading to repetition of one or more words. We analyzed the temporal structure of one-word, two-word, and three-word repetition disfluencies in the Switchboard Corpus (none-word = 30546, ntwo-word = 8102, nthree-word = 1606). Comparing durations of words preceding an interruption point to their repeated counterparts, we find that repetition is typically accompanied by prolongation, which mainly influences the last word preceding the interruption point. When prolongation does not provide enough time for planning upcoming speech—as there seems to be a temporal limit to prolongation—the speaker repeats parts of the utterance just produced. Our results demonstrate that the number of words repeated is determined both by word duration and by co-occurrence relations between words. Mixed effects logistic regression analysis revealed that longer words are less likely to be repeated (z=-24.45, p<.0001). However, the number of words repeated does not reduce to duration: controlling for word duration, the more frequent a two-word sequence, the less likely it is to be interrupted by a restart (z=35.43, p<.0001). Longer repetitions are produced when a shorter repetition would result in restarting speech production from the middle of a cohesive word sequence.
Speech adaptation to kinematic recording sensors
Authors: Dromey Christopher , Hunter Elise
Published: November 2016

Measuring articulator movements can yield valuable insights into speech motor control, but attaching sensors to the articulators can affect speech. In order to measure the process of adaptation to the presence of kinematic sensors, 20 native English speakers read a sentence before the attachment of sensors to the tongue, lips, and jaw. They read it immediately afterwards, and then 5, 10, 15, and 20 minutes later. Participants read aloud continuously between recordings to encourage adaptation. Audio recordings were rated by 20 native English listeners using a visual analog scale with the endpoints labeled as precise and imprecise. Acoustic analysis involved segmenting the fricatives /s/ and /ʃ/ from the longer recording and computing spectral center of gravity and spectral standard deviation as well as fricative duration. Results of both perceptual and acoustic analysis revealed a change in speech precision over time, with all post attachment recordings receiving reduced precision ratings. Spectral mean decreased and standard deviation increased following sensor attachment; durations decreased over time. Precision ratings beyond the ten minute recording remained steady. The results show that speakers reached a height of adaptation after 10 minutes but did not at any point return to pre attachment precision levels.
Tongue root positioning in English voiced obstruents: Effects of manner and vowel context
Authors: Ahn Suzy , Davidson Lisa
Published: November 2016

Previous research on utterance-initial voiced stops in American English (AE) has shown that speakers enlarge the vocal cavity via tongue root advancement whether or not the stop is phonated when compared to voiceless stops (Ahn 2015). The current ultrasound study expands this line of research to examine two further variables: (a) utterance-initial fricatives/affricates and (b) effect of frontness of the following vowel. Participants included both monolingual (n = 4) and simultaneous bilingual (n = 7) AE speakers. Phrase-initial stops (/p,b,t,d,k,g/), fricatives (/f,v,s,z/), and affricates (/tʃ,ʤ/) were followed by /e/ or /u/. Most productions confirmed that both phonated and unphonated voiced stops/affricates had more tongue root advancement than voiceless ones, but a small proportion showed no difference between phonated, unphonated, and voiceless stops/affricates. Fricative productions were divided between no tongue root difference due to either voicing or phonation, and greater advancement for voiced fricatives regardless of phonation. Tongue root advancement may be less prevalent for fricatives because weakening of the frication can also facilitate the conditions for phonation. A prediction that tongue root advancement for voicing before /e/ might be limited by the positioning requirements of the front vowel was weakly supported, especially for fricatives. The potential effects of bilingual speakers are also addressed.
An ultrasound study of tongue position during Hindi laryngeal contrasts
Authors: Ahn Suzy
Published: November 2016

Initiating or maintaining phonation during stop closure involves several adjustments, including tongue root advancement to enlarge oral cavity volume (Westbury 1983). Ultrasound imaging shows that in English, the tongue is more advanced for phonologically voiced stops, whether phonated or unphonated (Ahn 2015). The current study uses ultrasound to examine tongue positioning during Hindi stops. Hindi has a unique four-way laryngeal contrast: voiced, murmured, voiceless unaspirated, and voiceless aspirated. Eight native Hindi speakers recorded phrase-initial stops at three places of articulation (labial, dental, velar) followed by the low vowel /a/. Results show a clear distinction in tongue position between voiced and voiceless unaspirated/aspirated stops. The tongue root is advanced for voiced stops in comparison to voiceless stops. However, there is no difference in tongue root position between voiceless unaspirated and aspirated stops. Murmured stops showed variation among speakers in comparison to other stops, while the majority of speakers show more advanced tongue root compared to voiceless stops. The results suggest that tongue root advancement facilitates phonation in Hindi. Thus, in Hindi, tongue root position corresponds to a phonological distinction in phonation most notably between voiced unaspirated stops and voiceless stops, whereas in English, tongue root position reflects a more abstract phonological distinction in voicing that does not correspond to phonation.
Revisiting articulatory positions of Japanese vowels as a function of duration on the basis of analysis of large-scale speech corpora
Authors: Kagomiya Takayuki
Published: November 2016

The purpose of this study is to illustrate certain features of the place of articulation of Japanese vowels on the basis of formant frequency. For this purpose, two types of relationship between vowel duration and formant frequency were examined. The first of these relationships was the correlation between speaking rate and formant frequency. Speech materials are obtained from two large-scale speech corpora: Electrotechnical Laboratory Spoken Word database (ETL-WD) and The corpus of spontaneous Japanese (CSJ). The results of analyses showed that as speaking rate slows, articulations get more distinct: open vowels increase in openness, close vowels increase in closeness, front vowels increase in frontness, and back vowels increase in backness. The second relationship was between formant frequencies and vowel length. The result of this analysis showed that place of articulation is more distinct in long vowels than in short vowels. The exception was the back vowel /u/, all of which did not show greater backness in long vowels. This result supports previous arguments that Japanese /u/ is not a typical back vowel.
Co-articulation of unreleased final stops to preceding vowels in Cantonese: An ultrasound study
Authors: Yiu Suki
Published: November 2016

Unreleased final stops are more susceptible to reduction than their released counterparts, thus co-articulatory information on the preceding vowel is important to signal place contrasts of post-vocalic stops. This ultrasound study examines the gestural co-ordination of a VC sequence of monosyllabic words in Cantonese, a language which has preserved phonemic contrasts of six unreleased final stops /k, t, p, ng, n, m/ to form a VC sequence with three vowels /a, ɐ, ɔ/. We expect properties of /t, k/ to be (i) only immediately present at the vowel offsets (i.e. minimal co-articulation), or (ii) present from vowel midpoints to offsets (i.e. gradual co-articulation). If the /t, k/ contrast is (iii) consistently present throughout the vowel from onset to offset, it indicates phonologization of the /t,k/ contrast from the stops to the preceding vowels. Preliminary SS ANOVA results show that the lingual contours at vowel midpoints have early lingual raising into final stop constrictions, and the vowel offsets look more like the upcoming stops than the preceding vowels. This agrees with Khouw & Ciocca’s 2006 acoustic study, that unreleased final stops use C-to-V co-articulation to strengthen the place contrast.
The articulation of /ɹ/ in New Zealand English
Authors: Heyne Matthias , Wang Xuan , Dorreen Kieran , Derrick Donald , Watson Kevin
Published: November 2016

A large number of studies have investigated the articulation of approximant /ɹ/ in American English (AE) (e.g., Delattre & Freeman, 1968). This research has found that a low third formant (F3), the main acoustic cue signaling rhoticity, can be achieved using many different tongue configurations; the two main tongue shapes used for /ɹ/ are “tip-down” (“bunched”) and “tip-up” (“retroflex”) (cf. Hagiwara, 1994). While speakers likely employ various “trading relationships” to maintain a constantly low F3 across production strategies (Guenther et al., 1999), they have access to a pool of variation, which some use to form complex and idiosyncratic patterns of allophony (Mielke et al., 2016). Such patterns may arise during speech acquisition (Magloughlin, 2016). This study focuses on a non-rhotic dialect, New Zealand English (NZE), to test whether dialect rhoticity constrains idiosyncratic allophony. Ultrasound video was collected for 63 speakers articulating 13 words containing tokens of /ɹ/ in different phonetic environments. Analysis aims to determine whether NZE speakers utilize the same tongue gestures as seen in AE, and whether they display similar patterns of allophonic variation. The data include productions from 12 children (under 10) and 13 youth (11-18), allowing examination of /ɹ/ during childhood development.
Assessment of areas of the English-Japanese bilingual brain by using functional MRI
Authors: Asano Keiko , Sugano Hidenori , Arai Hajime , Nakajima Madoka , Aoki Shigeki
Published: November 2016

Bilinguals are often determined by how early they are exposed to L2 and the length of their immersion in the L2 environment, both of which affect factors that are important for acquiring language. To analyze the relationship between these, the language function of English-Japanese bilinguals was assessed using fMRI. In order to aim to observe differences in the brain, language function areas were activated by tasks specific to L2 usage. There were 24 English-Japanese bilingual speakers, average age of 25, categorized into four groups according to the age of exposure (before or after age 8), and the length of exposure (longer or shorter than 5years):Early Long (EL), Early Short (ES), Late Long (LL) and Late Short (LS). A PHILIPS Achieva 3.0T TX MRI machine was used to scan the subjects. Tasks consisted of hearing a short story in Japanese (Issunboshi) and English (Peter Rabbit) and their reverse plays by comparison of BOLD oxygenation levels. Focus was given to Broca’s area, Wernicke’s area and the premotor cortex. This study showed that broad areas of the premotor cortex were activated in ES and LS. EL and LL scans showed localization in Wernicke’s area. Since function in Broca’s area and the premotor cortex were consistent in ES and LS, it was assumed that these areas are necessary for proficiency and plasticity of language.
Effects of attention on lexically-informed perceptual learning for speech and letter perception
Authors: Drouin Julia R. , Monto Nicholas R. , Graham Stephen , Ose Jacqueline , Theodore Rachel M.
Published: November 2016

Listeners use lexical information to adjust the mapping to prelexical representations in both the auditory and visual modalities, a phenomenon referred to as lexically-informed perceptual learning (LIPL). Recent research points to attention mechanisms as potential constraints on this type of learning; learning is attenuated when listeners explicitly note anomalies in the speech input, and learning is negatively correlated with performance on tasks of attention-switching control. Here we examine whether graded lexical recruitment as modulated by attention influences LIPL in speech (Experiment 1) and print (Experiment 2). All participants completed a training phase where they were exposed to an ambiguous sound (midway between /s/ and /ʃ/) or an ambiguous grapheme (midway between H and N). Attention was manipulated during exposure by asking participants to make a lexical decision, a syntactic decision, or a decision regarding surface variation (i.e., amplitude, color). All participants then completed a categorization task to assess LIPL. The results to date indicate that LIPL is influenced by attention; the magnitude of the learning effect was not equivalent among the exposure conditions for either modality. However, differences between the two modalities were observed, which are considered with respect to the neural systems that support spoken and written language.
What the f***: An acoustic-pragmatic analysis of meaning in The Wire
Authors: Gold Erica , McIntyre Dan
Published: November 2016

The award-winning television drama, The Wire, contains a famous scene in which Detectives Moreland and McNulty discuss the crime scene they are investigating using only variations of a single expletive—fuck. Despite limited vocabulary, viewers are able to extract meaning and interpret the scene. This study considers all of the expletives produced in the scene, and carries out an acoustic analysis of / ʌ /—F1~F3 (midpoint and averages) and vowel duration. These measurements are then used in combination with Gricean (Grice 1975) and neo-Gricean (e.g. Horn 1984) pragmatic analysis in an attempt to categorize the intended meaning of fuck as: intensification, confusion, dissatisfaction or suspicion (Fairman 2009). Vowel measurements are considered for Moreland and McNulty individually, and vowel normalization is carried out in order to determine pragmatic categorizations across both detectives. This paper argues that acoustic-phonetic analysis can augment Gricean and neo-Gricean pragmatic analysis by providing a means of determining whether what appears at a lexical level to be conversationally implicated meaning is in fact conventional implicature conveyed at the phonetic level.
Multiuser and multiple-input-multiple-output underwater acoustic communication using time reversal
Authors: Shimura Takuya , Kida Yukihiro , Deguchi Mitsuyasu , Meguro Kohji , Watanabe Yoshitaka , Ochi Hiroshi
Published: November 2016

Time reversal is an effective method of channel equalization for underwater acoustic communication. Its temporal and spatial focusing effect collects long time spread signals due to a rich multipath environment inherent in underwater acoustics. Additionally, it is easy to compensate Doppler frequency shift after time reversal focusing. Recently, demands for multiuser or multiple-input-multiple-output (MIMO) communication have increased widely for multiple autonomous underwater vehicles (AUVs) or high rate underwater acoustic network communication. Similarly, in Japan Agency Marine-Earth Science and Technology (JAMSTEC), a plan of multiple AUVs operation is being progressed. Time reversal is a promising solution also for such multiuser or MIMO communication by realizing space division multiplexing (SDM) based on its spatial focusing and nulling effect without sacrificing data transmission rate. In this study, the performance of time reversal is analyzed with simulation or real data comparing with orthogonal frequency-division multiplexing (OFDM) as a conventional or commonly used method. As results, the ability of time reversal to suppress multiuser or multistream interferences is much better than those of maximum ratio combining (MRC), zero forcing (ZF) or minimum mean-square error (MMSE) OFDM, in both vertical and horizontal communication.
A covert underwater acoustic communication method based on spread spectrum digital watermarking
Authors: Yang Shaofan , Guo Zhongyuan , Ren Qunyan , Guo Shengming
Published: November 2016

The covert underwater acoustic communication is necessary under some circumstances when the contents of transmission or location of transmitter are required to be concealed. In this paper, the signal transmitter and the information detector are designed, which hides the spread spectrum digital watermark (SSDW) into the log-spectrum of dolphin whistles that are as a carrier and detects SSDW by matched filtering in the same log-spectrum. Various factors of noise, carrier and multipath in channels may degrade the performance of the method. In order to analyze their effects, corresponding channel models in log-spectrum domain are derived from the additive Gaussian noise channel and the underwater time-varying acoustic multipath channel. Results suggests that the effects of channel noise and the carrier are equivalent to that of two additive Gaussian noise terms attached to the correct decision and the proposed method also has a good multipath extension tolerance performance. Preliminary results obtained form at-sea experiments showed that the data rate can achieve 6 bps and bit error rate (BER) under 10-3 in the distance of 5 km.
Wave physics of the frequency difference autoproduct: Helmholtz equation analysis
Authors: Dowling David R. , Worthmann Brian M.
Published: November 2016

The frequency-difference autoproduct (Δf-AP) is a quadratic product of solutions of the inhomogenous Helmholtz equation that differ only in frequency, and may be easily constructed from the Fourier transform of measured time-domain signals. Recent findings involving beamforming (Abadi et al., 2012, JASA 132, 3018-3029) and matched field processing (Worthmann et al., 2015, JASA 138, 3549-3562) suggest that the Δf-AP is similar to an acoustic field at the difference frequency, even when the difference frequency lies below the recorded signal’s bandwidth. This presentation provides mathematical analysis that supports this interpretation and indicates its limitations, along with examples from a Lloyd’s mirror environment where a frequency sweep from 1-2kHz was broadcast from 100m below the reflecting surface out to a range of 2km. In particular, the Δf-AP in time-independent, inhomogeneous, multipath environments should be locally indistinguishable from an acoustic field at the difference frequency when: (i) the in-band acoustic propagation is well described by a ray-path sum, (ii) the in-band field gradient is dominated by phase (not amplitude) variations, and (iii) the products of the signal bandwidth and ray travel-time differences are large enough so that a signal-bandwidth average suppresses ray-path cross terms from the quadratic product. [Sponsored by ONR and NSF.]
Design, construction, and evaluation of an omni-directional loudspeaker (Dodecahedron)
Authors: Landi Maryam , Naderyan Vahid , Woolworth David S.
Published: November 2016

Dodecahedron loudspeaker (Dodec) is an omni-directional sound source in the shape of a 12-sided loudspeaker with each side being a pentagon. The omni-directionality of this sound source makes it mainly applicable in room acoustical and sound insulation measurements and research as it can excite and saturate the room as much as possible. Dodec is a good approximation of a point sound source. Commercially available omni-directional loudspeakers are not economically efficient for some purposes. This paper outlines a simple and inexpensive Dodec loudspeaker designed, constructed, and evaluated using ISO 140 and ISO 3382 standards as reference as part of an independent coursework. The Dodec was evaluated in an anechoic chamber. The measured directivity of this Dodec meets the standards for omni-directionality at all frequencies.
Acoustical energy relations in auditoriums
Authors: Gao Jianliang , Tang Shiu-Keung , Zhao Yuezhe
Published: November 2016

Extensive objective energy-based parameters have been measured in three auditoriums (2 scale models and 1 site survey) in the present study. Mono-aural measurements in the frequency range from 125 Hz to 4000 Hz (octave band) were conducted in unoccupied auditoriums according to the standard ISO 3382-1: 2009. Acoustical parameters, namely, the clarity C80, the definition D50, the early sound level Le, the late sound level Ll, the sound strength G and the center time Ts, have been estimated through analyzing the impulse responses measured in each auditorium. These parameters were spectrally averaged according to the most accepted criteria for sound quality evaluation in auditoriums and were expressed as a function of source-receiver distance. The experimental results were compared with predictions by classical and existing theoretical models proposed for concert halls and churches. A semi-empirical model based on the measured values of early and late sound levels is proposed in this work. The good agreement between predicted values and experimental data of clarity, definition, sound strength, and center time in the auditoriums analyzed indicates that the newly proposed model can be used for design predictions with reasonable accuracy.
Absorption coefficient: Dead or alive? Results of the “ASTM C423 Inter Laboratory Study"
Authors: Sauro Ronald
Published: November 2016

In 2009 and 2011, papers were presented questioning the procedures used to measure absorption and the conversion to an “Absorption Coefficient.” Part of the problem was the results of these conversions resulted in coefficients above 1.0. These results indicated a problem with the process or with the conversion to an “Absorption Coefficient.” Since that time enough data have been presented to the ASTM to result in an Inter Laboratory Study (ILS) on the efficacy of ASTM C-423 and other similar worldwide standards. Many corporate and independent laboratories took part in this study and the results of this ILS will be presented in this paper. These results helped show that the process of measuring absorption and the calculation of the “Absorption Coefficient” has had a basic flaw in it ever since it was first proposed in the 1920s. Proposed changes are discussed as well as proposed new calculations for use in calculating absorption in rooms. This should result in more accurate and consistent calculations of reverberation times for acoustic consultants. It is hoped that these results will result in a new standard for these measurements.
Low frequency analysis of acoustical parameters of emotional speech for use with functional magnetic resonance imaging
Authors: Moriarty Peter M. , Vigeant Michelle C. , Liu Pan , Gilmore Rick , Wolf Rachel , Cole Pamela M.
Published: November 2016

A mother’s voice plays a pivotal role in the social development of her child. Extreme exposure to vocalized anger in the home environment can weaken a child’s ability to manage their emotions and potentially compromise basic societal opportunities. It is therefore critical to understand the vehicle of the emotional content in speech, known as prosody, and specifically the neurological interactions of a mother’s voice with her child. Functional magnetic resonance imaging (fMRI) was used to measure children’s brain activity while stimulated by recorded sounds of mothers speaking with an angry, happy, sad, and neutral affect. Activity was measured in response to prosodic (e.g., pitch period variations, speech rate) and voice quality features (e.g., spectral distribution, jitter). Block-style fMRI analysis often uses mean values of these acoustic features taken over the length of each utterance, usually lasting many seconds or repetition time (TR) multiples. In an effort to retain some of the time-varying prosodic information of the mothers’s speech, this study included utterance-level spectral analysis of these acoustic features below the Nyquist frequency of the MRI. Preliminary results support the utility of such low-frequency analysis as a method for generating affect-differentiable information. [Work supported by NIH R21 104547.]
Sequential calls and associated behavior in captive bearded seals (Erignathus barbatus)
Authors: Mizuguchi Daisuke , Tsunokawa Masatoshi , Kawamoto Mamoru , Kohshima Shiro
Published: November 2016

Bearded seals produce complex underwater sounds suggested to function as territorial and/or courtship signals. However, little is known about behavioral context of the vocalization, mainly because direct observation is difficult in the wild. In this study, we recorded underwater sounds and behaviors of three captive bearded seals (an adult male and two adult females) in Otaru aquarium, Japan, between March 2012 and April 2016, in order to identify the caller and to record association between vocalization and behaviors. The male continuously vocalized from December until April with a peak in March, equivalent to breeding season in the wild. In contrast, the females vocalized only 1-2 weeks in March or April. The male and the females produced 3 and 5 call types, respectively, sharing 2 call types. The 3 call types of the male occurred in a regularly ordered sequence that was stable during this study. The females responded to the male sequential calls by nuzzling against the throat of vocalizing male during the breeding season, when the females also actively vocalized. Our results suggest that underwater vocalization of bearded seals might be used as a courtship signal between male and female possibly to advertise their reproductive status.
Music in the brain: The neuronal control of bird song
Authors: Fee Michale
Published: November 2016

Whether we are speaking, swimming, or playing the piano, we are crucially dependent on our brain’s capacity to reliably step through a learned sequence of states. Songbirds provide a marvelous animal model in which to study this phenomenon. Using newly developed technologies for monitoring and manipulating the activity of neurons in the brain of singing bird, we have identified circuits in the songbird brain that perform key functions of vocal production and learning. One of these circuits produces a highly precise representation of time in the brain—essentially a clock. Another circuit produces highly variable output that drives large fluctuations in the songs of juvenile birds, allowing them to creatively explore different vocal patterns during learning. I will combine these observations to propose a simple theory of how brains learn and perform such sophisticated behaviors as speech and music.
Development and field application of early warning system for harmful algal blooms (red-tide) early warning using ultrasound wave, Korea
Authors: Kang Donhyug , Kim Hansoo , Jung Seungwon , Kim Mira , Kim Byoung-Kweon
Published: November 2016

The harmful algal blooms (HABs) are affecting the ecosystems, coastal fisheries, and social economics in Korea. In the case of 2013 summer season, massive damage due to HABs (species: Cochlodinium polykrikoides) was reached to $23 million during August, 2013 in Korea. The most important things for minimizing of HABs damage is rapidly detection in initial stage. For this purpose, we have developed a real-time HABs detection system using ultrasound. The integrated system is composed by several sensors (3.5 MHz frequency, temperature and salinity, Chlorophyll, Dissolved oxygen), power supply, network communication, and remote control modules. For evaluating performance of the developed system, several experiments were intensively implemented in the laboratory and in-situ environments during summer seasons, 2013-2016. As a result, both of the performance tests are confirming the acoustic backscattering signal increases with the number of C. polykrikoides. Furthermore, the integrated system shows successfully in-situ performance for real-time red-tide detection and corresponding environmental data.
Size estimation of walleye pollack (Theragra chalcogramma) by using a broadband split-beam system
Authors: Imaizumi Tomohito , Sadayasu Kazuhiro , Akamatsu Tomonari
Published: November 2016

Recently, broadband quantitative echo sounders have been developed. These systems can measure single echo traces from individual fish with high range resolution. They can be used for the accurate size distribution by measuring the target strength. On the other hand, walleye pollack is one of the important species for stuck management in Japan. They form a school at juvenile stage. We compared the captured fish size using bottom trawl net with the acoustically estimated values. We conducted the survey in July 2015 in east side of off Hokkaido, Japan, using the fisheries research vessel Kaiyo-maru No. 5 (495 tons), which is equipped with narrowband echo sounder transducers (EK-60, Kongsberg, 38, 70, 120, and 200 kHz). The broadband split-beam transducer (FSS-SBX, Furuno) was deployed at the ship sideboard. All of the clock of the system were synchronized for comparison of data. More single echo traces could be measured using the broadband system than those measured by the narrowband system. Fork lengths were estimated at 3~70 cm based on the maximum normalized target strength value: -60 dB. We confirmed that good agreement of size distribution between catch and acoustic estimation. The broadband systems may be helpful tool for estimating body size of fish.
Multi-dimensional numerical simulation of sound propagation with background flow using constrained interpolation profile method
Authors: Fukuda Akihiro , Okubo Kan , Oshima Takuya , Tsuchiya Takao , Kanamori Masashi
Published: November 2016

To date, numerical simulation for sound wave propagation has been widely investigated as a result of advances in computer technology. For acoustic imaging and prediction, the development of accurate and effective analysis methods in time domain has become an important technical issue. The constrained interpolation profile (CIP) method, a novel low-dispersive numerical scheme, is a type of method of characteristics (MOC) employing a co-located grid system. In our past study, we have applied the CIP method to solving the linearized sound propagation equation. MOC is the calculation method which transforms governing equations of acoustic field into advection equations to solve the acoustic fields. Therefore, the method should be suitable for solving sound propagation considering the background flow effect, e.g., prediction of sound noise environment generated from a propulsion system of aircrafts or rockets. In the study, we proposed and examined the calculation method of sound propagation in an arbitrary background flow using CIP method. We made a numerical comparison between proposed method and the linearized Euler equations (LEE) method. The presentation has clarified that the CIP method is more accurate and effective for solving sound propagation in a strong and/or heterogeneous background flow.
Thévenin acoustics
Authors: Williams Randall P. , Hall Neal A.
Published: November 2016

Thévenin’s theorem can be applied to the analyses of acoustic systems, without limitation to systems that have been reduced to analogous circuit models. The method is particularly convenient in the analysis of acoustic scattering when the scattering object is mobile. In this presentation, the method is illustrated through an alternative derivation of the well-known “mass law” for transmission through a partition and is also applied to the case of acoustic scattering from a rigid, mobile cylinder of arbitrary size in an ideal plane progressive wave. Differences between the conventional solution approach for such problems and the Thévenin-inspired method are discussed, along with the potential benefits of taking such an approach for the simplification of other problems in physical acoustics.
Direct aeroacoustic simulations and measurements of flow and acoustic fields around a recorder with tone holes
Authors: Yokoyama Hiroshi , Miki Akira , Hamasuna Ryoma , Onitsuka Hirofumi , Iida Akiyoshi
Published: November 2016

Direct aeroacoustic simulations and experiments were performed regarding the flow and acoustic fields around a recorder, which is one of air-reed instruments. The present simulations reproduced the jet oscillations and acoustic radiation around the recorder with tone holes. The effects of conditions of the tone holes and the jet velocity on the flow and acoustic fields are discussed.