Coda Types Research Articles

The active space of sperm whale codas: inter-click information for intra-unit communication.

Sperm whales (Physeter macrocephalus) are social mega-predators who form stable matrilineal units that often associate within a larger vocal clan. Clan membership is defined by sharing a repertoire of coda types consisting of specific temporal spacings of multi-pulsed clicks. It has been hypothesized that codas communicate membership across socially segregated sympatric clans, but others propose that codas are primarily used for behavioral coordination and social cohesion within a closely spaced social unit. Here, we test these hypotheses by combining measures of ambient noise levels and coda click source levels with models of sound propagation to estimate the active space of coda communication. Coda clicks were localized off the island of Dominica with a four- or five-element 80m vertical hydrophone array, allowing us to calculate the median RMS source levels of 1598 clicks from 444 codas to be 161 dB re. 1 μPa (IQR 153-167), placing codas among the most powerful communication sounds in toothed whales. However, together with measured ambient noise levels, these source levels lead to a median active space of coda communication of ∼4 km, reflecting the maximum footprint of a single foraging sperm whale unit. We conclude that while sperm whale codas may contain information about clan affiliation, their moderate active space shows that codas are not used for long range acoustic communication between units and clans, but likely serve to mediate social cohesion and behavioral transitions in intra-unit communication.

A prominence account of the Northern Mam weight hierarchy

Northern dialects of the Mayan language Mam have a ternary weight scale for assigning stress, with the added wrinkle that syllables with glottal codas are heavier than those with other coda types: VV > Vʔ > VC > V. This ranking is initially surprising under the currently accepted prominence theory of weight (Ryan 2019, 2020), where all codas are equally moraic in all contexts. However, a phonetic experiment undertaken by Kuo & Elkins (2022) on the Northern Todos Santos Mam variety shows that Vʔ (i.e. syllables with glottal codas) are realized as lengthened glottalized vowels without a [ʔ] release, with vowel length intermediate between that of V and VV. Consequently, the Mam hierarchy VV > Vʔ > VC falls out from the relative phonetic prominence of syllable types, consistent with Ryan’s account. In Ryan’s analysis, VV attracts stress away from VC because vocalic moras are more prominent than consonantal moras (enforced via the constraint VV→MAIN). We build on this analysis and propose that in Mam, Vʔ attracts stress away from VC because of its higher prominence. This result leads to a typological prediction, where differences in the phonological weight of Vʔ and other VC should fall out from language-specific phonetic realizations of Vʔ.

Evidence from sperm whale clans of symbolic marking in non-human cultures

Culture, a pillar of the remarkable ecological success of humans, is increasingly recognized as a powerful force structuring nonhuman animal populations. A key gap between these two types of culture is quantitative evidence of symbolic markers-seemingly arbitrary traits that function as reliable indicators of cultural group membership to conspecifics. Using acoustic data collected from 23 Pacific Ocean locations, we provide quantitative evidence that certain sperm whale acoustic signals exhibit spatial patterns consistent with a symbolic marker function. Culture segments sperm whale populations into behaviorally distinct clans, which are defined based on dialects of stereotyped click patterns (codas). We classified 23,429 codas into types using contaminated mixture models and hierarchically clustered coda repertoires into seven clans based on similarities in coda usage; then we evaluated whether coda usage varied with geographic distance within clans or with spatial overlap between clans. Similarities in within-clan usage of both "identity codas" (coda types diagnostic of clan identity) and "nonidentity codas" (coda types used by multiple clans) decrease as space between repertoire recording locations increases. However, between-clan similarity in identity, but not nonidentity, coda usage decreases as clan spatial overlap increases. This matches expectations if sympatry is related to a measurable pressure to diversify to make cultural divisions sharper, thereby providing evidence that identity codas function as symbolic markers of clan identity. Our study provides quantitative evidence of arbitrary traits, resembling human ethnic markers, conveying cultural identity outside of humans, and highlights remarkable similarities in the distributions of human ethnolinguistic groups and sperm whale clans.

Place assimilation and perceptual salience: Korean listeners' perception of English and Korean coda consonants

This paper examined Korean listeners'' perceptual patterns of coda consonants in the context of English and Korean place assimilations. This study also investigated whether perceptual salience was affected by assimilation type (i.e., labial place assimilation and velar place assimilation) and coda type (i.e., /t/, /d/, and /n/ in English, and /t/, /n/, /p/, and /m/ in Korean). In a discrimination experiment, English and Korean stimuli involving place assimilation were presented to twenty native-Korean listeners. The same response rates involving a target syllable and a compound word including the target syllable (e.g., gree[n], gree[ŋ] cup in English, and ga[n] ''liver'', ga[ŋ]gineung ''liver function'' in Korean) were analyzed. Results showed considerable perceptual differences between English and Korean stimuli. Korean coda consonants were less distinct than English coda consonants in the context of assimilation. Furthermore, perceptual salience was strongly affected by assimilation type in the Korean stimuli, whereas the effects of coda type were revealed only in the English stimuli. These findings were discussed with respect to absence or presence of a stop release, perceptual salience rankings of coda consonants, and perceptual asymmetry between stops and nasals.

Vocal repertoires and insights into social structure of sperm whales (Physeter macrocephalus) in Mauritius, southwestern Indian Ocean

AbstractSperm whales communicate using codas (stereotyped click sequences). Females and juveniles live in long‐term social units, and units with similar coda repertoires share vocal clan membership. Vocal clans exhibit culturally defined differences in their multilevel social structure. Here, we aimed to identify different social units among sperm whales in Mauritius in the southwestern Indian Ocean, and to describe and compare their coda repertoires to investigate the presence of different vocal clans. We conducted six boat‐based surveys between 2008 and 2013, during which 101 different individuals were photo‐identified. Analysis of associations between 22 resighted individuals divided them into four candidate social units, but a lack of resightings impedes solid delineation of social units. Based on number and rhythm of clicks, at least 24 discrete coda types were detected among 4,767 analyzed codas using two different classification methods. Comparison of coda repertoires recorded from seven sperm whale groupings revealed the possible existence of two sympatric vocal clans, but the size differences of recorded repertoires warrant caution of interpretation. To further evaluate social structuring and the presence of different vocal clans in this region, future surveys should aim at obtaining long‐term sighting and acoustic data, and cover a more extensive area.

Deep Machine Learning Techniques for the Detection and Classification of Sperm Whale Bioacoustics

We implemented Machine Learning (ML) techniques to advance the study of sperm whale (Physeter macrocephalus) bioacoustics. This entailed employing Convolutional Neural Networks (CNNs) to construct an echolocation click detector designed to classify spectrograms generated from sperm whale acoustic data according to the presence or absence of a click. The click detector achieved 99.5% accuracy in classifying 650 spectrograms. The successful application of CNNs to clicks reveals the potential of future studies to train CNN-based architectures to extract finer-scale details from cetacean spectrograms. Long short-term memory and gated recurrent unit recurrent neural networks were trained to perform classification tasks, including (1) “coda type classification” where we obtained 97.5% accuracy in categorizing 23 coda types from a Dominica dataset containing 8,719 codas and 93.6% accuracy in categorizing 43 coda types from an Eastern Tropical Pacific (ETP) dataset with 16,995 codas; (2) “vocal clan classification” where we obtained 95.3% accuracy for two clan classes from Dominica and 93.1% for four ETP clan types; and (3) “individual whale identification” where we obtained 99.4% accuracy using two Dominica sperm whales. These results demonstrate the feasibility of applying ML to sperm whale bioacoustics and establish the validity of constructing neural networks to learn meaningful representations of whale vocalizations.

The Effects of Sentential Context on the Perception of Assimilated Speech by L2 Listeners

The aims of this study were to examine the effect of sentential context on perceptual compensation for assimilation and to compare compensation patterns between English and Korean listeners with a high proficiency level in English. To these ends, we conducted two experiments involving English coronal place assimilation. In the discrimination experiment, two types of stimuli (i.e., compound words and sentences) were presented. In the identification experiment, a target token including one of the two types of codas (i.e., coronal and non-coronal consonants) was embedded in a semantically neutral sentence. The results showed that in the discrimination experiment both listener groups demonstrated higher detection rates in sentences rather than in words. However, the Korean listeners were not as sensitive as the English listeners to phonetic differences of coda consonants in the unviable change context, and they showed more variations in detection rates than the English listeners. The results of the identification experiment presented a significant effect of coda type of target tokens on both listener groups. In sum, the L2 advanced learners were able to use sentential context to perceive assimilated speech, as were the L1 listeners.

Socially segregated, sympatric sperm whale clans in the Atlantic Ocean.

Sperm whales (Physeter macrocephalus) are unusual in that there is good evidence for sympatric populations with distinct culturally determined behaviour, including potential acoustic markers of the population division. In the Pacific, socially segregated, vocal clans with distinct dialects coexist; by contrast, geographical variation in vocal repertoire in the Atlantic has been attributed to drift. We examine networks of acoustic repertoire similarity and social interactions for 11 social units in the Eastern Caribbean. We find the presence of two socially segregated, sympatric vocal clans whose dialects differ significantly both in terms of categorical coda types produced by each clan (Mantel test between clans: matrix correlation = 0.256; p ≤ 0.001) and when using classification-free similarity which ignores defined types (Mantel test between clans: matrix correlation = 0.180; p ≤ 0.001). The more common of the two clans makes a characteristic 1 + 1 + 3 coda, while the other less often sighted clan makes predominantly regular codas. Units were only observed associating with other units within their vocal clan. This study demonstrates that sympatric vocal clans do exist in the Atlantic, that they define a higher order level of social organization as they do in the Pacific, and suggests that cultural identity at the clan level is probably important in this species worldwide.

Sperm whale codas may encode individuality as well as clan identity.

Sperm whales produce codas for communication that can be grouped into different types according to their temporal patterns. Codas have led researchers to propose that sperm whales belong to distinct cultural clans, but it is presently unclear if they also convey individual information. Coda clicks comprise a series of pulses and the delay between pulses is a function of organ size, and therefore body size, and so is one potential source of individual information. Another potential individual-specific parameter could be the inter-click intervals within codas. To test whether these parameters provide reliable individual cues, stereo-hydrophone acoustic tags (Dtags) were attached to five sperm whales of the Azores, recording a total of 802 codas. A discriminant function analysis was used to distinguish 288 5 Regular codas from four of the sperm whales and 183 3 Regular codas from two sperm whales. The results suggest that codas have consistent individual features in their inter-click intervals and inter-pulse intervals which may contribute to individual identification. Additionally, two whales produced different coda types in distinct foraging dive phases. Codas may therefore be used by sperm whales to convey information of identity as well as activity within a social group to a larger extent than previously assumed.

Individual, unit and vocal clan level identity cues in sperm whale codas.

The ‘social complexity hypothesis’ suggests that complex social structure is a driver of diversity in animal communication systems. Sperm whales have a hierarchically structured society in which the largest affiliative structures, the vocal clans, are marked on ocean-basin scales by culturally transmitted dialects of acoustic signals known as ‘codas’. We examined variation in coda repertoires among both individual whales and social units—the basic element of sperm whale society—using data from nine Caribbean social units across six years. Codas were assigned to individuals using photo-identification and acoustic size measurement, and we calculated similarity between repertoires using both continuous and categorical methods. We identified 21 coda types. Two of those (‘1+1+3’ and ‘5R1’) made up 65% of the codas recorded, were shared across all units and have dominated repertoires in this population for at least 30 years. Individuals appear to differ in the way they produce ‘5R1’ but not ‘1+1+3’ coda. Units use distinct 4-click coda types which contribute to making unit repertoires distinctive. Our results support the social complexity hypothesis in a marine species as different patterns of variation between coda types suggest divergent functions, perhaps representing selection for identity signals at several levels of social structure.

Differences in sperm whale codas between two waters off Japan: possible geographic separation of vocal clans

The sperm whale (Physeter macrocephalus) clan is a social unit that shares a similar repertoire of vocalizations called codas. Coda repertoires and clan structure are well studied in sperm whales of the eastern tropical Pacific, but information is limited in the western North Pacific. We compared sperm whale codas recorded from female and immature sperm whales in 2 areas near Japan, off the Kumano Coast and off the Ogasawara Islands, to determine whether different clans exist in these waters. Repertoires of coda types were different between the 2 areas, and the lengths of codas consisting of the same number of clicks were longer in duration near Kumano than near Ogasawara. Our results suggest that different vocal clans inhabit in these 2 areas. Such clear geographic structure of clans is not known in other waters in the Pacific and distinct environmental features may favor a clan in which members share a specific foraging strategy and coda repertoire, both of which likely are transmitted through social learning.

Individually distinctive acoustic features in sperm whale codas

Social animals may develop behavioural strategies that are based on individualized relationships among members. In these cases, there might be selection pressures for the development of identity signals and mechanisms that allow discrimination and recognition of particular individuals. Female sperm whales, Physeter macrocephalus, live in long-term, stable social units. Differential interactions among unit members suggest the need for an individual discrimination system. Sperm whales produce stereotyped series of click sounds called codas, which are thought to be used for communication. Although codas were initially proposed as individual signatures, later studies did not support this hypothesis. Using linear discriminant functions and Mantel tests, we tested variation within coda types as a means for individual identification, using recordings where codas were assigned to individual whales. While most coda types showed no indication of individual-specific information, individual differences that were robust to variation among recording days were found in the 5 Regular coda type. Differences in individual-specific information between coda types suggest that different coda types may have distinct functions.

Overlapping and matching of codas in vocal interactions between sperm whales: insights into communication function

Many animals engage in dyadic vocal exchanges. Studying the patterns of vocal output and spatial arrangement of individuals in these interactions can often reveal information concerning their function. Sperm whales, Physeter macrocephalus, frequently exchange short sequences of clicks, termed codas, in social contexts. We analysed the coda vocalizations of sperm whale social units encountered in two different oceans to test hypotheses about how coda exchanges are organized. We also used a dynamic recording array to estimate the spatial scale of these vocal interactions. Coda production was influenced by the timing and types of codas produced by other unit members, resulting in the production of duet-like sequences of coda exchanges between pairs of whales. Codas were more likely to be made within 2 s of another coda than expected by chance, and whales were more likely to match previously produced codas than expected by chance, although matching appeared to be largely a result of the matching of one particular coda type within each social unit. Patterns of overlapping and matching exchanges did not seem to be correlated with relatedness or social affiliation. These exchanges occurred over a range of spatial scales, and are thus likely to be functional both between whales that are near and between those that are comparatively far from one another. The context of these exchanges, reciprocity in coda overlapping, and the sequencing of exchanges into duet-like chains all suggest that coda overlapping and matching function to reinforce social bonds between whales.

Male sperm whale (Physeter macrocephalus) coda production and coda-type usage depend on the presence of conspecifics and the behavioural context

Sperm whale ( Physeter macrocephalus L., 1758 (= Physeter catodon L., 1758)) codas serve a communication function, but the message they carry remains unknown. Very few codas and extremely few coda types are available from males. For 7 years we studied the coda occurrence and the coda types produced by 15 males in different behavioural and encounter contexts. Of the 67 encounters, 615 codas were produced by nonsolitary males. Codas occurred in 60% of the nonsolitary encounters and 36% of the dive cycles. Four hundred and ninety codas have been categorized into 8 coda families and 25 distinctive coda types. Both the coda type used and the dive cycle phase in which codas occurred strongly depended on the behavioural context. This is the first time that coda types have been associated with particular behavioural contexts. The “Three plus” family coda types were mainly used by ascending or descending whales in feeding dive cycles. The “Regular” and “Progressive” families were used almost exclusively by interacting whales. The “Root” coda family was used exclusively at surface, mainly in altered dive cycles. The coda types used in these three behavioural contexts seem to carry different messages and are proposed to be named “dive cycle codas”, “social codas”, and “alarm codas”, respectively.

Compensatory responses to unexpected jaw loading during speech observed with magnetometry

Observations were made of articulator and formant trajectories during speech perturbed by unexpected mechanical loads applied to the jaw. Subjects produced multiple repetitions of the phrase ‘‘see X avis,’’ where X was one of ‘‘raw,’’ ‘‘rob’’ or ‘‘rod.’’ Perturbation forces were applied using a jaw-coupled robot, and triggered using a thresholding criterion applied to real-time tracking of the initial low to high transition in the first formant. Perturbations were delivered one out of every five repetitions, selected at random, with half applied upwards and half downwards, and forces sustained throughout the remainder of the utterance. Three EMMA sensors located on the anterior midsagittal surface of the tongue in addition to lower mandibular and upper lip sensors were used to track articulator positions. Audio and surface EMG (masseter, ABD, and OOS) were collected concurrently. Formants show initial deviation from control trajectories and then recovery that begins approximately 75 ms after the onset of perturbation. Compensation in most instances is nearly complete, even though jaw position does not recover its unperturbed trajectory. Perturbed tongue sensor trajectories are strongly distinguished by coda type, but show a pattern converging on the unperturbed tongue shape consistent with the tongue’s presumed role in effecting formant recovery.

Saisiyat as a Pitch Accent Language: Evidence from Acoustic Study of Words

This paper investigates the acoustic realization of lexical-level accent in Saisiyat, an endangered aboriginal language of Taiwan. Accent in Saisiyat usually falls on the ultimate syllable of content words. This phenomenon has been described in previous studies as either or Our measurements and analysis of various prosodic parameters of syllable rhyme (F0 height at onset, offset, peak, and valley, as well as pitch range, duration, slope, peak alignment, and intensity peak) suggest that accent in Saisiyat should be classified as pitch accent, because lexical accent is realized by means of specific F0 patterns, rather than duration and intensity. Thus, among three typological categories that have been proposed for languages (lexical tone, lexical stress, and lexical pitch accent), we propose that Saisiyat belongs to the category that has lexical pitch accent. 1. INTRODUCTION. (1) This paper investigates the acoustic realization of lexical level accent in Saisiyat, an endangered aboriginal language of Taiwan. Based on the results of this study, we propose that Saisiyat should be classified as a pitch accent language. Accent in Saisiyat content words is fixed on the final syllable, a property that it shares with certain other Taiwanese Austronesian languages. Yeh (2000) formulates the Saisiyat stress rule as follows: (2) V [right arrow] V [+stress] / _(C)# This rule, however, does not apply to function words or place names. (3) Zorc (1993) proposes a classification system for Austronesian languages based on their criteria for accent assignment. (4) According to this system, accent may be assigned on the basis of: (a) phonemic length and shortness; (b) phonemic accent (quantity or stress) as secondarily introduced, generally due to consonant loss, analogical leveling, or borrowing; (c) length contrasts in the ultima, resulting from compensation for the loss of a consonant; (d) phonemic length, as the result of coalescence (or crasis) of vowels, which does not correspond with stress (pitch accent); (e) phonemic length or shortness, retained sporadically as remnants of a preexisting system; (f) consonant length following a short vowel; (g) oxytone, with accent (with or without secondary vowel lengthening) falling regularly on the ultima; (h) paroxytone, with accent falling regularly on the penult; (i) proparoxytone, with accent falling regularly on a prepenultimate syllable; (j) PAn *e influences accent in a different way from the other vowels; (k) accent is used inflectionally, that is morphemic accent. Zorc categorized Tungho-Saisiyat (5) as belonging to category (d) and Saisiyat to category (g). This categorization of Saisiyat accent is congruent with previous observations that accent falls regularly on the ultimate syllable, and that vowel length does not affect pitch accent assignment. (6) No previous phonological description of accent/stress in Saisiyat has measured the acoustic properties of prominent syllables. The present study aims to provide a detailed acoustic analysis of Saisiyat accent by measuring the following parameters of syllable rhyme: F0 height at onset, offset, peak, and valley, as well as pitch range, duration, slope, peak alignment, and intensity peak. Analyzing these parameters will allow us to distinguish accented from unaccented syllables, as well as among the accents realized on different syllabic structures. The results of this study provide support for the classification of Saisiyat as a pitch accent language, because lexical accents are made prominent by means of specific F0 patterns rather than by means of duration and intensity. The remainder of this paper is organized as follows: section 2 reviews definitions of pitch accent, describes the acoustic parameters to be investigated, and reviews the literature on the influence of accent and coda types on the realization of prominent syllables. …

Do sperm whales share coda vocalizations? Insights into coda usage from acoustic size measurement

Group-specific communication signals are found in many group-living species. One example is group variation in the production of codas, which are short stereotyped patterns of clicks produced in social contexts, by sperm whales, Physeter macrocephalus. However, little is known about how codas are used by groups and individuals. We used the multipulse structure of sperm whale clicks to estimate the size of animals producing codas. Recordings of a single social unit containing nine largely unrelated animals made over a 1-month period yielded 879 codas of 32 distinctive types. We used an automatic technique to measure the interpulse interval of the clicks in these codas because the interpulse interval is closely related to the size of the animal. Ninety-four codas had sufficiently accurate measurements to be included in further analysis. Modes in the distribution of these measurements showed that more than one animal was producing codas. Comparing the measurements within coda types revealed that several coda types were produced by more than one animal. Thus, the codas recorded from these animals represent a shared repertoire, whereby coda production is not limited to a single animal and coda types are shared between individuals within the unit.

DEVELOPMENTAL SEQUENCES IN THE ACQUISITION OF ENGLISH L2 SYLLABLE CODAS: A Preliminary Study

This study examines the acquisition of English syllable codas by two native speakers of Vietnamese. Data were collected at three intervals over 1 year. Results indicate that a developmental sequence may exist and that this sequence may not be linear, with some longer (i.e., two and three member) codas emerging before some singleton codas. Furthermore, it was found that production type (e.g., with epenthesis or feature change) differed significantly by coda type and was indicative of acquisition processes. Finally, linguistic environment (preceding and following) and grammatical conditioning were found to significantly affect coda production and development.The author would like to thank Jun Liu, Mary Zampini, and the anonymous SSLA reviewers for their invaluable comments and suggestions on an earlier draft of this paper.

Spatial and temporal variation of sperm whale (Physeter macrocephalus) codas in the northern Gulf of Mexico

Sperm whale (Physeter macrocephalus) codas, short rhythmic patterns of clicks, were recorded annually from a towed linear array throughout the northern Gulf of Mexico during 2-week cruises spanning October 1991–August 1997. Codas were sampled and classified according to their temporal pattern and the number of clicks they contained. Regular codas, with equally spaced intervals between clicks, were analyzed along with irregular codas, with double intervals between the last two clicks. In this sample, short codas (less than five clicks) were more common than long codas (greater than six clicks). Preliminary analysis (n=11), using Student’s t-test, suggests that irregular codas may not vary in the northern Gulf of Mexico. When comparing interclick intervals, irregular coda types did not differ significantly across multiple years, and no spatial variation was observed. This pattern of similarity in coda types, if upheld with additional analyses, may suggest that coda repertoires remain stable over periods of years or that a resident population of animals may inhabit this area. Further analysis, however, is required to substantiate this supposition. [Work supported by Texas A&M University at Galveston.]

Coda communication by sperm whales (Physeter macrocephalus) off the Galápagos Islands

To gain insight into the function of sperm whale vocalizations known as codas (short, patterned series of clicks), sperm whales (Physeter macrocephalus) were tracked continuously for periods of days totalling months off the Galápagos Islands, Ecuador, and vocalizations were tape recorded systematically. In total, 1333 codas were classified according to their temporal pattern and the number of clicks they contained. Codas were found to be temporally very clustered, and could be categorized into 23 fairly discrete types. Sequential analysis of codas revealed that they overlapped one another according to type in a nonrandom way, and that type 5 tended to initiate coda exchanges. "Regular" coda types (with evenly spaced clicks) tended to occur with other regular coda types and "irregular" coda types (with one or two delayed final clicks) were heard with other irregular coda types. Codas may function principally as a means of communication, to maintain social cohesion within stable groups of females following periods of dispersion during foraging.