Classifying Emotions in Speech

Speech emotion recognition (SER) powers virtual assistants, mental health apps, and customer service analytics. This tutorial shows how to build annotation interfaces for categorical emotions, dimensional ratings, and mixed-emotion detection.

Emotion Annotation Approaches

There are several ways to annotate speech emotion:

Categorical: Discrete labels (happy, sad, angry)
Dimensional: Continuous scales (valence, arousal, dominance)
Mixed: Multiple emotions with intensity ratings
Segment-based: Different emotions at different timestamps

Categorical Emotion Classification

Basic Setup

annotation_task_name: "Speech Emotion Recognition"
 
data_files:
  - data/utterances.json
 
item_properties:
  id_key: id
  audio_key: audio_path
  text_key: transcript  # Optional transcript
 
audio:
  enabled: true
  display: waveform
  waveform_color: "#8B5CF6"
  progress_color: "#A78BFA"
  speed_control: true
  speed_options: [0.75, 1.0, 1.25]
 
annotation_schemes:
  - annotation_type: radio
    name: emotion
    description: "What emotion is expressed in this speech?"
    labels:
      - name: Happy
        description: "Joy, excitement, amusement"
        keyboard_shortcut: "h"
      - name: Sad
        description: "Sorrow, disappointment, grief"
        keyboard_shortcut: "s"
      - name: Angry
        description: "Frustration, irritation, rage"
        keyboard_shortcut: "a"
      - name: Fearful
        description: "Anxiety, worry, terror"
        keyboard_shortcut: "f"
      - name: Surprised
        description: "Astonishment, shock"
        keyboard_shortcut: "u"
      - name: Disgusted
        description: "Revulsion, distaste"
        keyboard_shortcut: "d"
      - name: Neutral
        description: "No clear emotion"
        keyboard_shortcut: "n"
    required: true

Adding Intensity

annotation_schemes:
  - annotation_type: radio
    name: emotion
    labels: [Happy, Sad, Angry, Fearful, Surprised, Disgusted, Neutral]
    required: true
 
  - annotation_type: likert
    name: intensity
    description: "How intense is this emotion?"
    size: 5
    min_label: "Very weak"
    max_label: "Very strong"
    conditional:
      depends_on: emotion
      hide_when: ["Neutral"]

Dimensional Emotion Annotation

The VAD (Valence-Arousal-Dominance) model:

annotation_task_name: "Dimensional Emotion Rating"
 
annotation_schemes:
  # Valence: negative to positive
  - annotation_type: likert
    name: valence
    description: "Valence: How positive or negative?"
    size: 7
    min_label: "Very negative"
    max_label: "Very positive"
 
  # Arousal: calm to excited
  - annotation_type: likert
    name: arousal
    description: "Arousal: How calm or excited?"
    size: 7
    min_label: "Very calm"
    max_label: "Very excited"
 
  # Dominance: submissive to dominant
  - annotation_type: likert
    name: dominance
    description: "Dominance: How submissive or dominant?"
    size: 7
    min_label: "Very submissive"
    max_label: "Very dominant"

Visual Scales (SAM)

Self-Assessment Manikin style:

annotation_schemes:
  - annotation_type: image_scale
    name: valence
    description: "Select the figure that matches the emotional valence"
    images:
      - path: /images/sam_valence_1.png
        value: 1
      - path: /images/sam_valence_2.png
        value: 2
      # ... etc
    size: 9

Mixed Emotion Detection

For speech containing multiple emotions:

annotation_schemes:
  - annotation_type: multiselect
    name: emotions_present
    description: "Select ALL emotions you detect (can be multiple)"
    labels:
      - Happy
      - Sad
      - Angry
      - Fearful
      - Surprised
      - Disgusted
      - Contempt
    min_selections: 1
 
  - annotation_type: radio
    name: primary_emotion
    description: "Which emotion is MOST prominent?"
    labels:
      - Happy
      - Sad
      - Angry
      - Fearful
      - Surprised
      - Disgusted
      - Contempt
      - Mixed (no dominant)

Comprehensive Emotion Annotation

annotation_task_name: "Comprehensive Speech Emotion Annotation"
 
data_files:
  - data/speech_samples.json
 
item_properties:
  id_key: id
  audio_key: audio_url
  text_key: transcript
 
audio:
  enabled: true
  display: waveform
  waveform_color: "#EC4899"
  progress_color: "#F472B6"
  height: 120
  speed_control: true
  speed_options: [0.5, 0.75, 1.0, 1.25]
  show_duration: true
  autoplay: false
 
# Show transcript if available
display:
  show_text: true
  text_field: transcript
  text_label: "Transcript (for reference)"
 
annotation_schemes:
  # Primary categorical emotion
  - annotation_type: radio
    name: primary_emotion
    description: "Primary emotion expressed"
    labels:
      - name: Happiness
        color: "#FCD34D"
        keyboard_shortcut: "1"
      - name: Sadness
        color: "#60A5FA"
        keyboard_shortcut: "2"
      - name: Anger
        color: "#F87171"
        keyboard_shortcut: "3"
      - name: Fear
        color: "#A78BFA"
        keyboard_shortcut: "4"
      - name: Surprise
        color: "#34D399"
        keyboard_shortcut: "5"
      - name: Disgust
        color: "#FB923C"
        keyboard_shortcut: "6"
      - name: Neutral
        color: "#9CA3AF"
        keyboard_shortcut: "7"
    required: true
 
  # Emotional intensity
  - annotation_type: likert
    name: intensity
    description: "Emotional intensity"
    size: 5
    min_label: "Very mild"
    max_label: "Very intense"
    required: true
 
  # Dimensional ratings
  - annotation_type: likert
    name: valence
    description: "Valence (negative to positive)"
    size: 7
    min_label: "Negative"
    max_label: "Positive"
 
  - annotation_type: likert
    name: arousal
    description: "Arousal (calm to excited)"
    size: 7
    min_label: "Calm"
    max_label: "Excited"
 
  # Voice quality
  - annotation_type: multiselect
    name: voice_qualities
    description: "Voice characteristics (select all that apply)"
    labels:
      - Trembling voice
      - Raised pitch
      - Lowered pitch
      - Loud/shouting
      - Soft/whisper
      - Fast speech rate
      - Slow speech rate
      - Breathy
      - Tense/strained
      - Crying
      - Laughing
 
  # Genuineness
  - annotation_type: radio
    name: authenticity
    description: "Does the emotion seem genuine?"
    labels:
      - Clearly genuine
      - Likely genuine
      - Uncertain
      - Likely acted/fake
      - Clearly acted/fake
 
  # Confidence
  - annotation_type: likert
    name: confidence
    description: "How confident are you in your annotation?"
    size: 5
    min_label: "Guessing"
    max_label: "Certain"
 
annotation_guidelines:
  title: "Emotion Annotation Guidelines"
  content: |
    ## Listening Instructions
    1. Listen to the entire clip before annotating
    2. You may replay as many times as needed
    3. Focus on the VOICE, not just the words
 
    ## Emotion Categories
    - **Happiness**: Joy, amusement, contentment
    - **Sadness**: Sorrow, disappointment, melancholy
    - **Anger**: Frustration, irritation, rage
    - **Fear**: Anxiety, nervousness, terror
    - **Surprise**: Astonishment, startle
    - **Disgust**: Revulsion, contempt
    - **Neutral**: Calm, matter-of-fact
 
    ## Tips
    - Consider tone, pitch, speaking rate
    - The transcript may not match the emotion
    - When unsure between two emotions, choose the stronger one
    - Use the intensity scale for unclear cases
 
output_annotation_dir: annotations/
output_annotation_format: jsonl

Output Format

{
  "id": "utt_001",
  "audio_url": "/audio/sample_001.wav",
  "transcript": "I can't believe this happened!",
  "annotations": {
    "primary_emotion": "Surprise",
    "intensity": 4,
    "valence": 2,
    "arousal": 6,
    "voice_qualities": ["Raised pitch", "Fast speech rate"],
    "authenticity": "Clearly genuine",
    "confidence": 4
  },
  "annotator": "rater_01",
  "timestamp": "2024-12-05T10:30:00Z"
}

Segment-Level Emotion

For longer audio with changing emotions:

annotation_schemes:
  - annotation_type: audio_segments
    name: emotion_segments
    description: "Mark time segments with different emotions"
    labels:
      - name: Happy
        color: "#FCD34D"
      - name: Sad
        color: "#60A5FA"
      - name: Angry
        color: "#F87171"
      - name: Neutral
        color: "#9CA3AF"
 
    segment_attributes:
      - name: intensity
        type: likert
        size: 5

Quality Control

quality_control:
  attention_checks:
    enabled: true
    gold_items:
      - audio: "/audio/gold/clearly_happy.wav"
        expected:
          primary_emotion: "Happiness"
          intensity: [4, 5]  # Accept 4 or 5
      - audio: "/audio/gold/clearly_angry.wav"
        expected:
          primary_emotion: "Anger"

Tips for Emotion Annotation

Full listening: Always listen to the complete clip
Voice focus: The emotional information is in HOW things are said
Cultural awareness: Expression norms vary across cultures
Fatigue management: Take breaks - emotion annotation is demanding
Calibration: Regular team discussions improve consistency

Next Steps

Add speaker diarization for multi-speaker emotion tracking
Set up crowdsourcing for large-scale collection
Calculate inter-annotator agreement for emotion tasks

Documentation at /docs/features/audio-annotation.