% Internal ICASSP 2027 draft using the official ICASSP 2026 template bundled % in this repository. Replace the class/style files when the 2027 author kit % is released, and remove every visible \todo{} marker before submission. % Compile from this directory with: make \documentclass{article} \usepackage{spconf} \usepackage{amsmath,amssymb,graphicx,hyperref,xcolor} \newcommand{\todo}[1]{\textcolor{red}{\textbf{[TODO: #1]}}} \newcommand{\vect}[1]{\boldsymbol{#1}} \setlength{\emergencystretch}{2em} \title{WHEN SHOULD AN EGOCENTRIC CONVERSATIONAL AGENT SPEAK? PROBING AND ADAPTING OMNI MODELS FOR MULTIPARTY FLOOR ACTION} % TODO: Insert the final author list and affiliations after the ICASSP 2027 % review policy and author order are finalized. \name{Internal Manuscript Draft} \address{} \begin{document} \ninept \maketitle \begin{abstract} An egocentric conversational agent operating among several people must decide whether to speak or keep listening before it generates a response. EgoSpeak operationalizes this problem using recordings from human camera wearers: causal first-person audio--video forms the observation, and the wearer's future speaking behavior forms the action target. The wearer is thus a data-collection surrogate rather than the deployed system. EgoSpeak evaluates separately extracted audio--visual features with Transformer, GRU, and Mamba temporal models; whether end-to-end pretrained omni models that jointly process raw audio and video expose the fine-grained cues required for a decision every 200~ms remains unclear. We probe representative omni backbones using frozen readout, parameter-efficient tuning, and causal side branches that preserve recent audio and visible-person evidence. The study tests whether a global omni state underrepresents other-person activity and whether local evidence compensates without making the agent passive. An EasyCom event protocol measures false agent entries during multi-other exchanges at matched recall of wearer-derived onset targets. Exploratory Qwen2.5-Omni-3B results motivate this hypothesis but do not yet establish a cross-model limitation or determine the final adapter. \todo{After the train-side study is locked, name the selected backbones and adapter and insert: frozen/PEFT/local deltas, multi-other false-entry reduction at 80\% onset recall, onset/yield non-degradation, and 95\% intervals.} \end{abstract} \begin{keywords} conversational agents, turn-taking, speech initiation, egocentric video, omni models \end{keywords} \section{Introduction} \label{sec:intro} We consider a conversational agent equipped with an egocentric camera and microphone and deployed in a scene where several people may speak. Before response generation and speech synthesis, its causal floor controller must decide every 200~ms whether to continue listening, begin speaking, or yield. A pause in dyadic dialogue may invite a response; in multiparty interaction it may instead mark a handover between two other people. An agent that reacts only to acoustic availability can therefore interrupt a conversation that it should continue observing. Existing datasets do not contain autonomous agents making these decisions at scale. Following EgoSpeak \cite{kim2025egospeak}, we use human egocentric recordings to construct supervision: the camera wearer defines the first-person sensor origin, and the wearer's observed speaking behavior defines the desired floor-action target. This is an imitation-learning proxy for a future agent under comparable observations. Throughout the paper, \emph{wearer} names this dataset role and target channel; it is neither the deployed agent nor a semantic model input. Response content and closed-loop effects of deploying an agent remain outside our scope. EgoSpeak already establishes real-time speech-initiation prediction in causal, untrimmed egocentric video. It combines separately pretrained ResNet-50 and wav2vec2 feature extractors with Transformer/LSTR, single-layer GRU, and Mamba temporal models, forecasting the camera wearer and aggregate other-person activity over the next two seconds \cite{kim2025egospeak}. Thus our novelty is not the task definition or the use of first-person data. The unresolved model question is whether an end-to-end pretrained audio--visual omni backbone, operating on causal raw media, exposes an adequate state for this dense floor-action controller. To our knowledge, such omni representations have not been systematically evaluated or adapted for the EgoSpeak task. Our working hypothesis is specific. An omni model may retain broad scene and speech semantics while its global causal state makes recent prosody, activity boundaries, and individual visible-speaker motion difficult for a shallow 5-Hz head to recover. This would appear as inaccurate prediction of other-person activity and poorly timed agent entries, especially in multiparty exchanges. A causal local side branch may compensate by preserving recent audio and anonymous person-level evidence before fusion with the global state. This is a hypothesis to test, not an assumed omni-model deficiency: frozen, parameter-efficiently tuned, and locally augmented variants must be compared within each backbone. Voice Activity Projection (VAP) provides the broader future-activity view of turn taking \cite{ekstedt2022vap}. EgoSpeak's role-relative output preserves compatibility with that view, but its aggregate ``others'' channel discards whether the same or different visible people produced recent activity. Moreover, conventional per-frame average precision can hide the behavioral failure of entering during an exchange between others. We therefore retain the dense EgoSpeak target while adding event evaluation of agent entry and yield; event-oriented work likewise emphasizes recall, false alarms, and latency rather than a single frame-level score \cite{jiang2026turnbench}. Related work supplies complementary parts of the problem. Egocentric talking-to-me detection predicts whether a completed utterance addresses the camera wearer and benefits from long-term social context \cite{kong2024sicnet}. Multiparty VAP grounds future activity in visible face tracks to predict floor shifts and next visible speakers \cite{qi2026muvap}. The former is generally utterance-level rather than continuous anticipation; the latter predicts visible participants rather than the action of an egocentric conversational agent represented by a wearer-derived target. Our gap is therefore narrower than ``audio--visual multiparty turn taking'': we study whether omni representations support direct, continuous agent floor-action prediction and whether causal local evidence helps when the visible participant set changes. We call this task \emph{egocentric floor-action projection}. The study asks four questions: (RQ1) how accurately a frozen global omni state predicts the wearer-derived agent target and other-person activity; (RQ2) whether standard parameter-efficient tuning recovers missing performance; (RQ3) whether causal local audio and person-level visual evidence provide complementary information; and (RQ4) whether any aggregate gain reduces false agent entries without making the controller globally passive. EasyCom is suitable because it provides synchronized egocentric audio--video, per-person tracks, and voice activity \cite{donley2021easycom}. Target-of-speech annotations, when used, are analysis strata only and are never model input or required output. The intended contributions are therefore: a controlled cross-backbone study of pretrained omni representations for EgoSpeak-style floor action; a lightweight local-evidence adaptation selected from pre-registered candidates; and a behavior-aligned event evaluation that maps wearer demonstrations to agent entry and yield decisions. Current Qwen2.5-Omni observations are motivation, not a claim that all omni models intrinsically fail. Likewise, track-consistent cross-attention becomes the final method only if it beats pooled, no-ID, and capacity-matched controls. \begin{figure}[t] \centering \fbox{\parbox[c][1.05in][c]{0.94\columnwidth}{\centering \todo{After model selection, draw the final system figure. For now it must show the shared experiment interface: raw causal AV, backbone-specific global readout, frozen/PEFT/local-adapter branches, optional recent audio and anonymous person histories, and the common $10\times3$ head. Mark causal cutoffs, trainable modules, parameter budgets, and source-boundary resets.}}} \caption{Planned omni-model study for egocentric conversational floor action. The local adapter remains a candidate family until the controlled train-side comparison is complete.} \label{fig:method} \end{figure} \section{Methods} \label{sec:method} \subsection{Wearer-relative activity projection} At decision time $t$, the model observes only the causal stream $\mathcal{X}_{\leq t}$ and predicts $K=10$ future bins at $\Delta=0.2$~s. For bin $k$, the target $\vect{y}_{t,k}=[y^{\mathrm{bg}},y^{\mathrm{w}},y^{\mathrm{o}}]$ denotes background, camera-wearer activity, and activity by one or more other people. Wearer--other overlap is allowed; hence this is not a three-way softmax. The output is \begin{equation} \hat{\vect{Y}}_t=f_\theta(\mathcal{X}_{\leq t})\in[0,1]^{K\times3}, \qquad q_t=\hat y^{\mathrm{w}}_{t,1}, \label{eq:task} \end{equation} where $q_t$ is the immediate wearer-entry score used by the event protocol. It is interpreted as an \emph{entry} score only in wearer-silent opportunity windows; elsewhere it remains a future-activity probability. This retains the EgoSpeak target and evaluation while exposing a deployable 5-Hz decision signal. \subsection{Omni backbones and representation protocols} Let $m$ index an omni backbone and let $\vect{g}^{(m)}_t$ be a backbone-specific causal global readout at the same physical cutoff $t$. Qwen2.5-Omni \cite{xu2025qwenomni} is the currently implemented family; Qwen2.5-Omni-3B, Qwen2.5-Omni-7B, and MiniCPM-o~4.5 \cite{cui2026minicpmo45} form the planned initial comparison. These models have different native streaming APIs, temporal tokenization, hidden dimensions, and adaptation interfaces. We therefore emphasize within-backbone deltas rather than treating raw cross-model scores as a pure architecture ranking. Every supported backbone is evaluated under three representation protocols: (i) a frozen global readout with a dimension-matched prediction head; (ii) a pre-registered parameter-efficient adaptation budget; and (iii) the same global readout augmented by causal local evidence. Input cutoffs, EgoSpeak targets, context duration, training examples, head capacity, and evaluation are held fixed whenever the backbone permits it. A failure of one LoRA recipe is reported as that recipe's result, not as proof that the backbone cannot adapt. \todo{Implement and audit one adapter for each planned backbone. For every model, document model revision, processor, native audio/video rates, exact hidden-state readout, causal/streaming semantics, context limit, dtype, trainable LoRA targets/rank, parameter count, peak memory, and P50/P95 latency. Verify no future frames or samples enter $\vect g^{(m)}_t$. If a model cannot expose a comparable causal state, report it as unsupported rather than inventing a non-equivalent readout. Add future backbones only before the experiment protocol is locked.} \subsection{Candidate local-evidence adaptation} The current hypothesis is that global omni states preserve broad semantic context but may make recent prosody, activity boundaries, and individual visual motion difficult for a shallow floor head to recover. From the most recent $L_a$ seconds, a local encoder produces audio evidence $\vect A_t$ and, optionally, an anonymous visible-person set $\mathcal P_t$. A generic candidate adapter is \begin{equation} \vect z^{(m)}_t=\vect g^{(m)}_t+ \gamma_t H_\phi(\vect g^{(m)}_t,\vect A_t,\mathcal P_t), \qquad \gamma_t\vert_{\mathrm{init}}=0, \label{eq:adapter} \end{equation} followed by the common prediction head. Local evidence is derived from the same causal raw media, not close microphones, transcripts, speaker labels, or future frames. We evaluate candidates in increasing structural complexity: pooled recent audio/vision; a capacity-matched temporal branch; a per-frame person set with no cross-time identity; a shared track-wise temporal encoder; and person--audio cross-attention. Only a candidate that improves the pre-registered event metric over simpler and capacity-matched controls becomes the final method. If person continuity is selected, temporary IDs route hidden state only---there is no ID embedding, name recognition, or cross-recording identity---and the set operator is permutation equivariant \cite{lee2019settransformer}. \todo{Run the candidate ladder before fixing $H_\phi$. Match trainable parameters and effective local history. Compare a shared local encoder across backbones (cross-model control) with each backbone's native local encoder (within-model control); do not mix these protocols in one claimed delta. For track candidates, specify visibility/age masks, gap/source resets, OFFSCREEN handling, and global-rename invariance. Describe only the selected architecture as the final method; move rejected candidates to ablations.} \subsection{Training objectives} The common main loss is class-balanced binary cross entropy over all horizons and activity channels. This dense EgoSpeak target is the only supervision required by the task. If a person-aware candidate survives the activity-only comparison, an optional auxiliary head predicts current active-speaker state: \begin{equation} \mathcal{L}=\mathcal{L}_{\mathrm{act}}+ \lambda_{\mathrm{asd}}\mathcal{L}_{\mathrm{asd}}. \label{eq:loss} \end{equation} Participant ID, target-of-speech, transcript, close-microphone audio, and future frames are never model inputs. Target-of-speech may stratify qualitative analysis but is not a predicted variable or a requirement for the primary multi-other event definition. \todo{First compare all representation/adaptation protocols with activity loss only. Then ablate +ASD for the selected person-aware candidate. Add an event-specific wearer onset/yield loss only as a separately reported extension. Select all coefficients and early stopping on a training-side calibration fold; do not inspect Sessions 1--3 during selection.} \subsection{Track source and deployment contract} Person-aware candidates first use dataset-provided boxes and anonymous IDs to isolate the value of local visual structure. A deployable version instead obtains causal tracklets from a face/head detector followed by an online multi-object tracker; no future-frame smoothing or cross-session recognition is permitted. EasyCom IDs are continued only across genuinely adjacent source segments and reset across redacted gaps. Ego4D IDs are local to a clip. \todo{If a person-aware candidate is selected, state precisely whether face or head boxes are used. Report provided-track coverage, mean/maximum people, occlusion gaps, track fragments, and source-gap resets for both datasets. Add either one online detector/tracker experiment or controlled box jitter, dropout, fragmentation, and ID-switch curves; otherwise limit every deployment claim to ``given causal participant tracklets.''} \section{Experiments} \label{sec:setup} \textbf{Data and splits.} We use the EgoSpeak EasyCom protocol: Sessions 4--12 for model development and Sessions 1--3 for final reporting. All architecture, checkpoint, threshold, and hyperparameter choices use training-side folds only. Inputs contain the camera stream and shared array audio available to the wearer; close-talking microphones, per-person voice labels, and target-of-speech labels are not model inputs. We also report aggregate activity forecasting on the EgoSpeak Ego4D split \cite{grauman2022ego4d}. Ego4D Audio-Visual Diarization supplies clip-local anonymous participant tracks; its per-person voice coverage on the 433-clip EgoSpeak split must be audited before reporting the same multi-other event analysis. \textbf{Backbone comparison.} The initial study covers Qwen2.5-Omni-3B, Qwen2.5-Omni-7B, and MiniCPM-o~4.5. For each backbone $m$, we first compare its frozen causal state $G_m$, a parameter-efficiently adapted state $P_m$, and local-evidence augmentation $G_m+L$. The primary diagnostic is the within-backbone change; cross-backbone absolute scores are secondary because native tokenization, pretraining, streaming interfaces, and hidden-state semantics differ. Common local encoders test whether adaptation transfers across global backbones, whereas native local encoders are a separate, model-specific protocol. All rows share physical input cutoffs, targets, data splits, and evaluation. Unsupported causal readouts are disclosed rather than replaced by offline or future-conditioned features. \todo{Implement the three backbone adapters and validate state timestamps with an impulse/cutoff test. Pre-register one matched PEFT budget and one common local branch. Report native-vs-common local encoders in separate table panels. Keep future model additions outside the confirmatory comparison once this matrix is locked.} \textbf{Event construction.} We derive \emph{wearer onset} events directly from the wearer activity target. A \emph{multi-other exchange} is a wearer-silent opportunity interval in which at least two distinct non-wearer participant IDs contribute temporally ordered speech activity. It is an observable interaction proxy, not a claim about the speakers' mental intent or addressee. Threshold $\tau_r$ is selected on the development split to obtain wearer-onset recall $r\in\{0.7,0.8,0.9\}$ and is then frozen. The primary metric is false wearer entries per minute of multi-other opportunity at matched onset recall; the headline operating point is $r=0.8$. We also report signed onset latency, wearer-yield recall/latency, and the original ten-horizon per-frame mAP. \todo{Freeze the event pairing and competing-risk rules, including the multi-other alternation window, minimum speech/silence, overlap, maximum onset delay, duplicate detections, one detection per event, track visibility, source boundaries, and group/offscreen cases. Publish train/test onset counts, multi-other events/minutes, number of distinct visible speakers, and exclusion counts. Manually audit at least 100 events. Treat all previously viewed Sessions 1--3 scores as exploratory; lock the protocol and model before the confirmatory three-seed run.} \textbf{Baselines and controls.} For each backbone we compare: frozen global state $G_m$; PEFT $P_m$; $G_m$ plus recent local audio; and $G_m$ plus pooled local audio--visual evidence. This compact matrix tests the representation hypothesis before investing in a complex fusion module. If local vision survives three seeds and the event gate, we then compare a parameter-matched temporal branch without person continuity, a separately trained per-frame/no-ID set branch, and a track-consistent branch. On a frozen track-aware checkpoint, a clip-consistent global renaming must leave outputs unchanged, whereas \emph{broken continuity} periodically remaps IDs while preserving every crop, timestamp, audio sample, and target. Time-shifted and removed vision provide additional alignment controls. \todo{Define the broken-continuity corruption before evaluation: remap only at pre-registered 1-s boundaries or report a fixed ID-switch-rate curve. Do not call a clip-consistent slot permutation ``broken ID.'' Verify unchanged crops, frame counts, audio, labels, and visibility masks. Train the no-ID/reset baseline from scratch with matched parameters; evaluate all test-time counterfactuals using one frozen checkpoint and one frozen threshold.} \textbf{Implementation and statistics.} All prediction heads run at 5~Hz and use an 8-s causal observation window; model-specific deviations required by a native streaming interface are stated explicitly. In the frozen protocol the omni backbone does not update. In PEFT and local protocols, trainable parameters and optimizer exposure are reported separately. Every temporal state resets at non-contiguous source boundaries. We report three seeds and mean$\pm$standard deviation. Confidence intervals for event metrics use paired cluster bootstrap over sessions/conversation blocks rather than treating adjacent frames as independent. Runtime includes P50/P95 decision latency, throughput, peak memory, and trainable parameter count. \todo{Fill optimizer, learning rate, batch size, epochs, feature dimensions, $L_a$, crop rate/resolution, number of heads/layers, $N_{\max}$, parameter count, hardware, and real-time latency after the architecture is frozen.} \section{Results and Analysis} \label{sec:results} \begin{table}[t] \caption{Exploratory Qwen2.5-Omni-3B local-branch evidence on EasyCom test Sessions 1--3. Values are percentages from one seed, not a cross-backbone or confirmatory result.} \label{tab:preliminary} \centering \small \resizebox{\columnwidth}{!}{% \begin{tabular}{lccc} \hline Model & 0.2-s mAP & 0.2-s wearer AP & Mean mAP\\ \hline Qwen-3B $G$+local A & 81.72 & 85.07 & 65.11\\ Qwen-3B $G$+local AV-pool & 82.03 & 85.09 & 65.40\\ \hline $\Delta$ visual & +0.30 & +0.02 & +0.29\\ \hline \end{tabular}} \end{table} Table~\ref{tab:preliminary} shows why aggregate mAP alone is insufficient. Pooled vision gives a small gain, while immediate wearer AP is nearly unchanged. This is compatible with either weak but useful social grounding or generic visual regularization; only matched-recall event evaluation and track-continuity controls can distinguish them. A separate Qwen-3B dense-cache diagnostic gave 58.16 mean mAP for its frozen readout and 56.20 for one LoRA recipe. Because that diagnostic used a different feature protocol, it is not combined numerically with Table~\ref{tab:preliminary}; it only shows why a fair, protocol-matched PEFT study remains necessary. \begin{table}[t] \caption{Planned cross-backbone EasyCom event evaluation. Lower $\mathrm{FP}_{\mathrm{mo}}$ is better; all rows use the same development-selected operating protocol. ``Local'' denotes the train-side selected common local-evidence candidate.} \label{tab:main} \centering \small \resizebox{\columnwidth}{!}{% \begin{tabular}{lccccc} \hline Backbone/protocol & $\mathrm{FP}_{\mathrm{mo}}$/min@$R=.8$ & Onset R & Onset latency & Yield R & Mean mAP\\ \hline Qwen-3B frozen & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ Qwen-3B PEFT & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ Qwen-3B + local & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ Qwen-7B frozen & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ Qwen-7B PEFT/local & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ MiniCPM-o frozen & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ MiniCPM-o PEFT/local & \todo{--} & \todo{--} & \todo{--} & \todo{--} & \todo{--}\\ \hline \end{tabular}} \end{table} \todo{Report Table~\ref{tab:main} as mean$\pm$standard deviation over three seeds, plus 95\% paired cluster-bootstrap confidence intervals for frozen vs PEFT and frozen vs local within each backbone. A general omni-representation claim requires a consistent pattern across at least two backbone families; an effect confined to Qwen must be stated as Qwen-specific. The behavior claim is supported only if multi-other FP/min decreases at matched wearer-onset recall without worse onset latency or wearer-yield recall. If the selected local candidate uses tracks, also report its paired intervals against no-ID and temporal-capacity controls.} \begin{table}[t] \caption{Conditional track-continuity counterfactual on the best track-aware model. This table is retained only if train-side selection chooses such a candidate; all rows reuse one frozen checkpoint.} \label{tab:counterfactual} \centering \small \resizebox{\columnwidth}{!}{% \begin{tabular}{lccc} \hline Track/visual evidence & $\mathrm{FP}_{\mathrm{mo}}$/min & Onset recall & 0.2-s mAP\\ \hline Correct tracks & \todo{--} & \todo{--} & \todo{--}\\ Global ID rename & \todo{--} & \todo{--} & \todo{--}\\ Broken continuity & \todo{--} & \todo{--} & \todo{--}\\ Time shifted & \todo{--} & \todo{--} & \todo{--}\\ Removed & \todo{--} & \todo{--} & \todo{--}\\ \hline \end{tabular}} \end{table} If a track-aware candidate is selected, Table~\ref{tab:counterfactual} is the continuity test. Global renaming must be numerically invariant because IDs carry no semantics. If the model exploits person history, correct tracks should outperform broken continuity even though both contain exactly the same per-frame people. If broken, time-shifted, and removed variants perform similarly to correct tracks, the defensible conclusion is additional capacity or generic visual context, not useful person-continuous reasoning. \todo{Add one compact error analysis split by model family, track visibility, number of visible people, overlap, track age/fragmentation, and backchannel/interruption proxy. Include event counts with every rate. Move rejected PEFT recipes and fusion candidates to supplementary material unless they directly explain the selected method.} \textbf{Qualitative evidence.} For a multi-other exchange, visualize per-person speech activity and track IDs, wearer ground truth, the frozen-global and selected-local wearer-entry scores, and the single frozen threshold on one physical time axis. If the selected candidate is track-aware, also show its broken-continuity score. A useful example shows the frozen baseline rising at an other-speaker boundary while the selected adapter remains below threshold; a companion positive example must show that a real wearer onset is not suppressed. \todo{Do not hand-pick only successful clips. Before viewing the final test plots, freeze a deterministic selection rule and show: largest paired improvement, near-median improvement, one failure, and one correctly retained wearer onset. Include full local timelines and source frame times, not cropped screenshots without context. State that examples illustrate the aggregate event result and cannot establish it alone.} \section{Conclusion} \label{sec:conclusion} We study when an egocentric agent should enter or yield a multiparty floor, not merely whether someone will speak. The central question is model-agnostic: whether frozen or parameter-efficiently adapted omni representations expose the fine-grained floor cues required by a 5-Hz controller, and whether causal local evidence closes any gap. Dense activity forecasting supplies a common target, while matched-recall event evaluation tests whether an apparent gain actually prevents intrusions during multi-other exchanges. Current Qwen-3B results are exploratory motivation only. \todo{After the controlled study, state which backbone/adapter was selected, whether the representation pattern generalized beyond Qwen, the quantitative false-entry and onset/yield results, and the main deployment limitation. Do not infer success from aggregate mAP or selected examples alone.} \bibliographystyle{IEEEbib} \bibliography{references} \end{document}